| 1. |
- Hasan, Badrul, et al.
(author)
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Emergence of carbapenem-resistant Acinetobacter baumannii in hospitals in Pakistan
- 2014
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 63:1, s. 50-55
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Journal article (peer-reviewed)abstract
- The emergence of pan-resistance in bacterial pathogens poses a threat to human health. Carbapenem-resistant Acinetobacter baumannii has emerged as a serious challenge, causing nosocomial infection and community-acquired outbreaks in hospitals globally, including in Pakistan. We collected 90 Acinetobacter isolates from patients with secondary or nosocomial infections from different hospitals in Pakistan and screened for carbapenem-resistant strains. Of the 90 isolates, 59 were resistant to carbapenems. Among oxacillinase -encoding genes, blaOXA-51-like was common in all isolates, including in combination with blaOXA-23-like in 14 isolates; however, blaOXA-24-like and blaOXA-58-like were completely absent. Among metallo-β-lactamase-encoding genes, only blaNDM-1 was found in one isolate, while the other three genes, blaIMP, blaVIM and blaSIM, were completely absent. None of the isolates was found to harbour the blaCTX-M gene. The isolates were also tested for susceptibilities to a panel of different antibiotics belonging to several classes. Of all the drugs tested, tigecycline was the most effective with 80 % sensitivity amongst isolates, followed by colistin with 50 % sensitivity. Three categories of resistance were found in these isolates: extreme drug resistance in 26, pan-drug resistance in 19 and multidrug resistance in 87 isolates. The isolates exhibited a high resistance to cephalosporins, trimethoprim-sulfamethoxazole and β-lactam antibiotics, followed by tetracycline and β-lactam/β-lactam inhibitor combination, fluoroquinolone and aminoglycosides. The results show a prominent level of antibiotic-resistance phenotypes in A. baumannii and strongly suggest the need for full-scale national surveillance of carbapenem-resistant A. baumannii with particular emphasis on the newly identified NDM-1 (New Delhi metallo-β-lactamase-1).
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| 2. |
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| 3. |
- Abd, H, et al.
(author)
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Vibrio cholerae O139 requires neither capsule nor LPS O side chain to grow inside Acanthamoeba castellanii
- 2009
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In: Journal of medical microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 58:1Pt 1, s. 125-131
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Journal article (peer-reviewed)abstract
- Vibrio cholerae, the causative agent of cholera, has the ability to grow and survive in the aquatic free-living amoebaAcanthamoeba castellanii. The aim of the present study was to examine the ability of the clinical isolateV. choleraeO139 MO10 to grow inA. castellaniiand to determine the effect of the bacterial capsule and LPS O side chain on intracellular growth. Results from co-cultivation, viable counts, a gentamicin assay, electron microscopy and statistical analysis showed that the association ofV. choleraeO139 MO10 withA. castellaniidid not inhibit growth of the amoeba, and enhanced growth and survival ofV. choleraeO139 MO10 occurred. The wild-typeV. choleraeO139 MO10 and a capsule mutant or capsule/LPS double mutant grew insideA. castellanii. Neither the capsule nor the LPS O side chain ofV. choleraeO139 was found to play an important role in the interaction withA. castellanii, disclosing the ability ofV. choleraeto multiply and survive insideA. castellanii, as well as the role ofA. castellaniias an environmental host forV. cholerae.
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| 4. |
- Abu Al-Soud, Waleed, et al.
(author)
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Assessment of PCR-DGGE for the identification of diverse Helicobacter species, and application to faecal samples from zoo animals to determine Helicobacter prevalence.
- 2003
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 52:9, s. 765-771
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Journal article (peer-reviewed)abstract
- Helicobacter species are fastidious bacterial pathogens that are difficult to culture by standard methods. A PCR-denaturing gradient gel electrophoresis (PCR-DGGE) technique for detection and identification of different Helicobacter species was developed and evaluated. The method involves PCR detection of Helicobacter DNA by genus-specific primers that target 16S rDNA and subsequent differentiation of Helicobacter PCR products by use of DGGE. Strains are identified by comparing mobilities of unknown samples to those determined for reference strains; sequence analysis can also be performed on purified amplicons. Sixteen DGGE profiles were derived from 44 type and reference strains of 20 Helicobacter species, indicating the potential of this approach for resolving infection of a single host by multiple Helicobacter species. Some more highly related species were not differentiated whereas in highly heterogeneous species, sequence divergence was observed and more than one PCR-DGGE profile was obtained. Application of the PCR-DGGE method to DNA extracted from faeces of zoo animals revealed the presence of Helicobacter DNA in 13 of 16 samples; a correlation was seen between the mobility of PCR products in DGGE analysis and DNA sequencing. In combination, this indicated that zoo animals are colonized by a wide range of different Helicobacter species; seven animals appeared to be colonized by multiple Helicobacter species. By this approach, presumptive identifications were made of Helicobacter bilis and Helicobacter hepaticus in a Nile crocodile, Helicobacter cinaedi in a baboon and a red panda, and Helicobacter felis in a wolf and a Taiwan beauty snake. All of these PCR products (400 bp) showed 100 % sequence similarity to 16S rDNA sequences of the mentioned species. These results demonstrate the potential of PCR-DGGE-based analysis for identification of Helicobacter species in complex ecosystems, such as the gastrointestinal tract, and could contribute to a better understanding of the ecology of helicobacters and other pathogens with a complex aetiology.
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| 5. |
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| 6. |
- Amaya, E, et al.
(author)
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Antibiotic resistance patterns of intestinal Escherichia coli isolates from Nicaraguan children
- 2011
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In: Journal of medical microbiology. - : Microbiology Society. - 1473-5644 .- 0022-2615. ; 60:2Pt 2, s. 216-222
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Journal article (peer-reviewed)abstract
- In developing countries, diarrhoeal diseases are one of the major causes of death in children under 5 years of age. It is known that diarrhoeagenic Escherichia coli (DEC) is an important aetiological agent of infantile diarrhoea in Nicaragua. However, there are no recent studies on antimicrobial resistance among intestinal E. coli isolates in Nicaraguan children. The aim of the present study was to determine the antimicrobial resistance pattern in a collection of 727 intestinal E. coli isolates from the faeces of children in León, Nicaragua, between March 2005 and September 2006. All samples had been screened previously for the presence of DEC by multiplex PCR. Three hundred and ninety-five non-DEC isolates (270 from children with diarrhoea and 125 from children without diarrhoea) and 332 DEC isolates (241 from children with diarrhoea and 91 from children without diarrhoea) were analysed in this study. In general, antimicrobial resistance among the 727 intestinal E. coli isolates was high for ampicillin (60 %), trimethoprim–sulfamethoxazole (64 %) and chloramphenicol (11 %). Among individual E. coli categories, enteroaggregative E. coli isolates from children with and without diarrhoea exhibited significantly higher levels of resistance (P<0.05) to ampicillin and trimethoprim–sulfamethoxazole compared to the other E. coli categories. Resistance to ceftazidime and/or ceftriaxone and a pattern of multi-resistance was related to CTX-M-5- or CTX-M-15-producing E. coli isolates. The results suggest that E. coli isolates from Nicaraguan children have not reached the high levels of resistance to the most common antibiotics used for diarrhoea treatment as in other countries.
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| 7. |
- Andersson, Henrik, et al.
(author)
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T A microarray analysis of the murine macrophage response to infection with Francisella tularensis LVS
- 2006
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 55:8, s. 1023-1033
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Journal article (peer-reviewed)abstract
- The response of cells of the mouse macrophage cell line J774 to infection with Francisella tularensis LVS was analysed by means of a DNA microarray representing approximately 18 500 genes (20 600 clones). The adaptive response was modest at all time points, and at most, 81 clones were differentially regulated from the time point of uptake of bacteria (0 min) up to 240 min later. For all five time points, 229 clones fulfilled the criteria of being differentially regulated, i.e. the ratio between infected versus non-infected cells was at least 1.7-fold up- or down-regulated and P <0.05. It was found that many of the differentially regulated genes are known to respond to stress in general and to oxidative stress specifically. However, at 120 min it was observed that genes that lead to depletion of glutathione were upregulated. Possibly, this was a result of mechanisms induced by F. tularensis. Generally, there was a conspicuous lack of inflammatory responses and, for example, although tumour necrosis factor alpha (TNF-α) was upregulated at 0 min, a significant down-regulation was noted at all subsequent time points. When cells were treated with an inhibitor of inducible nitric oxide synthase (iNOS) or the antioxidant N-acetylcysteine (NAC), the infection-induced cytopathogenic effect was significantly inhibited. Together, the results suggest that F. tularensis LVS infection confers an oxidative stress upon the target cells and that many of the host-defence mechanisms appear to be intended to counteract this stress. The infection is characterized by a very modest inflammatory response.
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| 8. |
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| 9. |
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| 10. |
- Ansaruzzaman, M., et al.
(author)
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Characterization of enterotoxigenic Escherichia coli from diarrhoeal patients in Bangladesh using phenotyping and genetic profiling
- 2007
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In: J Med Microbiol. - : Microbiology Society. ; 56:2Pt 2, s. 217-222
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Research review (peer-reviewed)abstract
- A total of 99 isolates out of 370 colonization factor (CF)-positive, well-characterized enterotoxigenic Escherichia coli (ETEC) strains belonging to 13 different CF types isolated from diarrhoeal patients admitted to the hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh, were tested. The isolates were selected at random based on expression of the major CFs prevailing in Dhaka, Bangladesh, from 1996 to 1998. These isolates were characterized by O-antigenic serotyping, randomly amplified polymorphic DNA (RAPD) analysis and biochemical fingerprinting using the PhenePlate (PhP) system. The 99 ETEC isolates belonged to 10 O serogroups, the predominant ones being O6 (n=28), O115 (n=20) and O128 (n=20). Most isolates of serogroup O6 (CS1+CS3, 11/14; CS2+CS3, 5/8) belonged to the same PhP/RAPD type (H/f), whereas other isolates of serogroup O6 (n=12) belonged to different PhP/RAPD types (Si/f and F/c). Eleven serogroup O128 (CFA/I) isolates belonged to the same PhP/RAPD type (E/b), whereas the other O128 isolates formed different PhP/RAPD types. Fifteen (75%) serogroup O115 isolates (together with fourteen isolates from serogroups O25, O114, O142 and O159) demonstrated two closely related common groups by PhP typing (A and A1) and belonged to the same PhP/RAPD type (A/a). Three major clonal groups were identified among the ETEC strains in this study, largely based on O-antigenic type, CF expression pattern and toxin profile.
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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Burova, Larissa, et al.
(author)
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Immune complex binding Streptococcus pyogenes type M12/emm12 in experimental glomerulonephritis
- 2013
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 63, s. 1272-1280
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Journal article (peer-reviewed)abstract
- In a rabbit model, we have previously reported evidence for a pathogenic role of streptococcal IgG Fc-binding proteins (IgGFcBP) in poststreptococcal glomerulonephritis (PSGN). These proteins, of the M protein family, were shown to trigger anti-IgG production and enhance renal deposition of IgG and/or immune complexes (ICs), with resulting activation of complement and cytokine cascades. In the present study, type M12/emm12, group A streptococci (GAS) were found often to bind artificial ICs, viz. peroxidase anti-peroxidase rabbit IgG (PAP) or tetanus toxoid-anti-tetanus human IgG (TAT), rather than monomeric IgG. Animals injected with each of four IC binding clinical isolates (from patients with scarlet fever or PSGN) showed pronounced inflammatory and degenerative glomerular changes, morphologically similar to human PSGN, with membrane thickening and IgG and complement C3 deposition, as well as secretion of IL-6 and TNF-alpha by mesangial and endothelial cells. In contrast, non-binding strains (two from asymptomatic carriers and one from a PSGN case) failed to trigger any renal changes. Only the IC binding strains induced elevated titres of anti-IgG. Though the streptococcal binding component(s) has not been demonstrated, the selective binding of ICs by type M12/emm12 strains appears important for the well-known, marked nephritogenic potential of this GAS type.
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| 15. |
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| 16. |
- Dicksved, Johan, et al.
(author)
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Molecular characterization of the stomach microbiota in patients with gastric cancer and in controls
- 2009
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 58:4, s. 509-516
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Journal article (peer-reviewed)abstract
- Persistent infection of the gastric mucosa by Helicobacter pylori can initiate an inflammatory cascade that progresses into atrophic gastritis, a condition associated with reduced capacity for secretion of gastric acid and an increased risk of developing gastric cancer. The role of H. pylori as an initiator of inflammation is evident but the mechanism for development into gastric cancer has not yet been proven. A reduced capacity for gastric acid secretion allows survival and proliferation of other microbes that normally are killed by the acidic environment. It has been postulated that some of these species may be involved in the development of gastric cancer; however, their identities are poorly defined. In this study, the gastric microbiota from ten patients with gastric cancer was characterized and compared with that from five dyspeptic controls using the molecular profiling approach terminal restriction fragment length polymorphism (T-RFLP), in combination with 16S rRNA gene cloning and sequencing. T-RFLP analysis revealed a complex bacterial community in the cancer patients that was not significantly different from that in the controls. Sequencing of 140 clones revealed 102 phylotypes, with representatives from five bacterial phyla (Firmicutes, Bacteroidetes, Proteobacteria, Actinobacteria and Fusobacteria). The data revealed a relatively low abundance of H. pylori and showed that the gastric cancer microbiota was instead dominated by different species of the genera Streptococcus, Lactobacillus, Veillonella and Prevotella. The respective role of these species in development of gastric cancer remains to be determined.
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| 17. |
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| 18. |
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| 19. |
- Edberg, Andreas, et al.
(author)
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A comparative study of three different PCR assays for detection of Mycoplasma genitalium in urogenital specimens from men and women
- 2008
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 57:Pt 3, s. 304-309
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Journal article (peer-reviewed)abstract
- The aim of this study was to compare conventional 16S rRNA gene PCR, real-time 16S rRNA gene PCR and real-time Mycoplasma genitalium adhesin protein (MgPa) gene PCR as detection methods for M. genitalium infection. The study also determined the prevalence of M. genitalium in male and female patients attending a sexually transmitted infections clinic in a rural area in the west of Sweden. First void urine (FVU) and/or urethral swabs were collected from 381 men, and FVU and/or cervical swabs and/or urethral swabs were collected from 298 women. A total of 213 specimens were used in the PCR comparative study: 98 consecutively sampled specimens from patients enrolled in the prevalence study, 36 consecutively sampled specimens from patients with symptoms of urethritis and 79 specimens from patients positive for M. genitalium by real-time MgPa gene PCR in the prevalence study. A true-positive M. genitalium DNA specimen was defined as either a specimen positive in any two PCR assays or a specimen whose PCR product was verified by DNA sequencing. The prevalence of M. genitalium infection in men and women was 27/381 (7.1 %) and 23/298 (7.7 %), respectively. In the PCR comparative study, M. genitalium DNA was detected in 61/76 (80.3 %) of true-positive specimens by conventional 16S rRNA gene PCR, in 52/76 (68.4 %) by real-time 16S rRNA gene PCR and in 74/76 (97.4 %) by real-time MgPa gene PCR. Real-time MgPa gene PCR thus had higher sensitivity compared with conventional 16S rRNA gene PCR and had considerably increased sensitivity compared with real-time 16S rRNA gene PCR for detection of M. genitalium DNA. Real-time MgPa gene PCR is well suited for the clinical diagnosis of M. genitalium.
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| 20. |
- Edberg, Andreas, 1974-, et al.
(author)
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Endocervical swabs transported in first void urine as combined specimens in the detection of Mycoplasma genitalium by real-time PCR
- 2009
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 58, s. 117-120
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Journal article (peer-reviewed)abstract
- The aim of this study was to determine whether a patient’s endocervical swab specimen can be transported in first void urine (FVU) as combined specimens for the detection of Mycoplasma genitalium by real-time PCR. The study also compared two different DNA extraction methods for observation of possible PCR inhibition. Three specimens, one endocervical swab specimen transported in 2-SP medium, one endocervical swab specimen transported in FVU and a FVU specimen, were collected from 329 women. All sample types underwent manual DNA extraction whereas in the DNA extraction study, 329 endocervical swab specimens transported in FVU were subjected to both manual Chelex and automated BioRobot M48 DNA extraction. A total of 100 endocervical swab specimens transported in FVU from patients PCR-negative for M. genitalium in the study were used in the PCR inhibition analysis. M. genitalium was detected in 25/329 (7.6 %) women. The endocervical swab specimens transported in 2-SP medium and transported in FVU were positive for M. genitalium in 17/25 (68 %) and 24/25 (96 %) women, respectively. The FVU specimens alone were positive for M. genitalium in 22/25 (88 %) women. In the DNA extraction study, M. genitalium DNA was detected in 24/329 (7.3 %) and 28/329 (8.5 %) of endocervical swab specimens transported in FVU subjected to manual Chelex extraction and automated BioRobot M48 extraction, respectively. Partial PCR inhibition was detected in 6% of samples subjected to manual Chelex extraction whereas no inhibition was detected with the automated BioRobot M48 extraction. Thus endocervical swab specimens transported in FVU demonstrate higher sensitivity than FVU specimens only and have considerably increased sensitivity compared with endocervical swab specimens transported in 2-SP medium for detection of M. genitalium DNA. Moreover, automated BioRobot M48 extraction was shown to be superior to a crude manual Chelex extraction, leaving no PCR inhibition and giving a slightly higher DNA yield and/or better sensitivity.
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| 21. |
- Ellis, M, et al.
(author)
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Assessment of the clinical utility of serial beta-D-glucan concentrations in patients with persistent neutropenic fever
- 2008
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In: Journal of medical microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 57:3Pt 3, s. 287-295
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Journal article (peer-reviewed)abstract
- The performance of the Fungitell assay was investigated in 100 patients with haematological malignancy undergoing chemotherapy who developed antibiotic-unresponsive neutropenic fever (AUNF). Serum β-d-glucan (BG) concentrations were significantly elevated on the first day of AUNF and all subsequent alternate days to day 10 in 38 patients who developed an invasive fungal infection (IFI) compared to 42 patients remaining free of such infections. The mean and median values of BG were 171.9±29.6 and 95.8 pg ml−1, respectively, for patients with IFI and 64.4±17.1 and 32.9 pg ml−1 for patients with only AUNF (P<0.0001). The differences remained significant over the 10 days despite antifungal therapy. The occurrence of ≥2 sequential concentrations of ≥80 pg ml−1 (‘positive’ test) was found to give the best overall option for diagnosis, with an accuracy of 81.3 %, sensitivity of 86.8 %, positive predictive value of 76.7 % and negative predictive value of 86.5 %. Of the patients with an IFI, 78 % developed a positive test at or before the clinical diagnosis was made – this occurred at a mean (range) of 1.25 (−14 to +14) days prior to the IFI diagnosis. By starting sampling of blood from the first day of neutropenia rather than from the first day of AUNF, 50 % of the patients with subsequent IFI would have been identified 5 days earlier. Increasing sampling to daily from alternate-day frequency did not further improve this earlier timing of an IFI diagnosis. A greater proportion of patients with persistent high levels of BG without overt IFI had severe enterocyte damage or mucositis than those with lower levels of BG without IFI (P=0.002). If the results of the initial BG test had been acted on to change antifungal therapy, discontinuation would have been inappropriate in 30 % of patients and would have delayed definitive antifungal therapy. Although the findings for the cohort of patients studied are very useful, there is inter-patient variability in the test's performance. An holistic diagnostic approach is therefore necessary to interpret the test results optimally. Future studies should address this in further detail as well as the impact of empirical antifungal drug use and patient outcome.
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| 22. |
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| 23. |
- Ericsson, Henrik, et al.
(author)
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Molecular grouping of Listeria monocytogenes based on the sequence of the inlB gene
- 2000
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 49:1, s. 73-80
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Journal article (peer-reviewed)abstract
- The major part of the gene inlB was sequenced in 24 strains of Listeria monocytogenes belonging to serovars 1/2a, 1/2b, 1/2c, 3b and 4b. A phylogenetic analysis based on the inlB nucleotide sequences showed that strains of serovars 1/2a and 1/2c were closely related, as well as those of serovars 1/2b and 3b. Strains sharing serovar 4b could be divided into two distinct groups. There were differences in amino-acid sequence between all serovars except between serovars 1/2b and 3b. Differences in amino-acid sequence were also seen within each of the serovars 1/2a and 4b. The data presented indicate that the inlB gene may be useful for typing purposes as an alternative or complement to serotyping.
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| 24. |
- Feizi, Neda, et al.
(author)
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Autophagy induction regulates influenza virus replication in a time-dependent manner
- 2017
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 66:4, s. 536-541
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Journal article (peer-reviewed)abstract
- Purpose. Autophagy plays a key role in host defence responses against microbial infections by promoting degradation of pathogens and participating in acquired immunity. The interaction between autophagy and viruses is complex, and this pathway is hijacked by several viruses. Influenza virus (IV) interferes with autophagy through its replication and increases the accumulation of autophagosomes by blocking lysosome fusion. Thus, autophagy could be an effective area for antiviral research. Methodology. In this study, we evaluated the effect of autophagy on IV replication. Two cell lines were transfected with Beclin-1 expression plasmid before (prophylactic approach) and after (therapeutic approach) IV inoculation. Results/Key findings. Beclin-1 overexpression in the cells infected by virus induced autophagy to 26 %. The log10 haemagglutinin titre and TCID50 (tissue culture infective dose giving 50% infection) of replicating virus were measured at 24 and 48 h post-infection. In the prophylactic approach, the virus titre was enhanced significantly at 24 h post-infection (P?0.01), but it was not significantly different from the control at 48 h post-infection. In contrast, the therapeutic approach of autophagy induction inhibited the virus replication at 24 and 48 h post-infection. Additionally, we showed that inhibition of autophagy using 3-methyladenine reduced viral replication. Conclusion. This study revealed that the virus (H1N1) titre was controlled in a time-dependent manner following autophagy induction in host cells. Manipulation of autophagy during the IV life cycle can be targeted both for antiviral aims and for increasing viral yield for virus production.
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| 25. |
- Forsell, Joakim, et al.
(author)
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Evaluation of factors affecting real-time PCR performance for diagnosis of Entamoeba histolytica and Entamoeba dispar in clinical stool samples
- 2015
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 64, s. 1053-1062
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Journal article (peer-reviewed)abstract
- Although PCR offers the potential for sensitive detection of parasites:there are several pitfalls for optimal performance, especially when DNA is extracted from a complex sample material such as stool. With the aid of a sensitive inhibitor control in a duplex real-time PCR (qPCR) for identification of Entamoeba histolytica and Entamoeba dispar we have evaluated factors that influenced the performance of the qPCR and have suggested a rationale to be used in the analysis of clinical samples. Pre-PCR processing was found to be of outmost importance for an optimal amplification since inhibitors caused false-negative results when higher amounts of sample were used. Stool sampling with a flocked swab (ESwab, Copan), yielding on average 173 mg, gave positive qPCR results in samples with cysts of E. dispar that were negative in serially diluted stool samples. The degree of inhibition found varied between samples and was not an on-off phenomenon. Even low-grade inhibition, shown as an increase of two cycles in the qPCR for the inhibitor control, could lead to false negativity in samples with low amounts of parasites. Lack of amplification in the qPCR due to inhibition could be overcome by dilution of the extracted DNA by 1/10-1/20. We also describe the use of guanidinium thiocyanate buffer for transport and storage of samples as well as a time-saving semi-automated DNA extraction method in an Arrow instrument (Nordiag) preceded by bead beating.
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| 26. |
- Gerner, Erik, 1986, et al.
(author)
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Sodium salicylate interferes with quorum-sensing-regulatedvirulence in chronic wound isolates of Pseudomonas aeruginosa in simulated wound fluid
- 2020
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 69:5, s. 767-780
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Journal article (peer-reviewed)abstract
- Introduction. An important factor for delayed healing of chronic wounds is the presence of bacteria. Quorum sensing (QS), a cell density-dependent signalling system, controls the production of many virulence factors and biofilm formation in Pseudomonas aeruginosa.Aim. Inhibition by sodium salicylate (NaSa) of QS-regulated virulence expression was evaluated in QS-characterized clinical wound isolates of P. aeruginosa, cultured in serum-containing medium.Methodology. Fourteen clinical P. aeruginosa strains from chronic wounds were evaluated for the production of QS signals and virulence factors. Inhibition of QS by NaSa in P. aeruginosa clinical strains, wild-type PAO1 and QS reporter strains was evaluated using in vitro assays for the production of biofilm, pyocyanin, siderophores, alkaline protease, elastase and stapholytic protease.Results. Six clinical strains secreted several QS-associated virulence factors and signal molecules and two were negative for all factors. Sub-inhibitory concentrations of NaSa downregulated the expression of the QS-related genes lasB, rhlA and pqsA and reduced the secretion of several virulence factors in PAO1 and clinical strains cultured in serum. Compared to serum-free media, the presence of serum increased the expression of QS genes and production of siderophores and pyocyanin but decreased biofilm formation.Conclusions.Pseudomonas aeruginosa from chronic wound infections showed different virulence properties. While very few strains showed no QS activity, approximately half were highly virulent and produced QS signals, suggesting that the targeting of QS is a viable and relevant strategy for infection control. NaSa showed activity as a QS-inhibitor by lowering the virulence phenotypes and QS signals at both transcriptional and extracellular levels.
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| 27. |
- Gonzales, Lucia, et al.
(author)
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Prevalence, seasonality and severity of disease of pathogenic Escherichia coli in children with diarrhea in Bolivia.
- 2013
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 62:11, s. 1687-1695
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Journal article (peer-reviewed)abstract
- The prevalence of infection caused by different categories of diarrhoeagenic E. coli (DEC) strains, including enteroaggregative (EAEC), enteropathogenic (EPEC), enterotoxigenic (ETEC), enteroinvasive (EIEC) and enterohaemorrhagic (EHEC) E. coli, in children who suffered from diarrhoea (n=3943) or did not have diarrhoea (n=1026) were analysed in two areas in Bolivia over a period of 4 years. We also analysed the seasonality of DEC infections and severity of diarrhoea in children with DEC infection and compared antibiotic resistance in DEC strains isolated from children with and without diarrhoea. Stool samples were analysed for the presence of DEC by culturing followed by PCR. The most prevalent DEC categories in samples from the children were: EAEC (11.2%); ETEC (6.6%); EPEC (5.8%); and EIEC and EHEC (<1%). DEC strains were isolated significantly more often from diarrhoea cases (21.6%) than from controls (17.6%; P=0.002). The number of children with diarrhoea associated with EAEC, EPEC and ETEC infections peaked in the Bolivian winter (April–September), although the proportion of DEC-positive stool samples was higher during the warm rainy season (October–March). High levels of antibiotic resistance were detected among the DEC strains. In particular, resistance to tetracycline and sulfamethoxazole–trimethoprim was significantly higher in strains isolated from individuals with diarrhoea than in samples from controls. The severity of disease in children infected with EAEC, EPEC and ETEC varied from mild to severe diarrhoea, although disease severity did not differ significantly between the different DEC categories. ETEC, EPEC and EAEC are commonly found in Bolivia and may cause severe disease in children.
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| 28. |
- Gonzales-Siles, Lucia, et al.
(author)
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Identification and capsular serotype sequetyping of Streptococcus pneumoniae strains
- 2019
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 68:8, s. 1173-1188
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Journal article (peer-reviewed)abstract
- Purpose. Correct serotype identification of Streptococcus pneumoniae (pneumococcus) is important for monitoring disease epidemiology and assessing the impacts of pneumococcal vaccines. Furthermore, correct identification and differentiation of the pathogenic S. pneumoniae from closely related commensal species of the mitis group of the genus Streptococcus are essential for correct serotype identification. Methodology. A new protocol for determining the existing 98 serotypes of pneumococcus was developed, applying two PCR amplifications and amplicon sequencing, using newly designed internal primers. The new protocol was validated using S. pneumoniae genome sequences, reference strains with confirmed serotypes and clinical isolates, and comparing the results with those from the traditional Quellung reaction or antiserum panel gel precipitation, in addition to real-time PCR analysis. The taxonomic identifications of 422 publicly available (GenBank) genome sequences of S. pneumoniae, Streptococcus pseudopneumoniae and Streptococcus mitis were assessed by whole-genome sequence average nucleotide identity based on blast (ANIb) analysis. Results. The proposed sequetyping protocol generates a 1017 bp whole cpsB region sequence, increasing resolution for serotype identification in pneumococcus isolates. The identifications of all GenBank genome sequences of S. pneumoniae were confirmed, whereas most of the S. pseudopneumoniae and almost all of the S. mitis genome sequences did not fulfil the ANIb thresholds for species-level identification. The housekeeping biomarker gene, groEL, correctly identified S. pneumoniae but often misclassified S. pseudopneumoniae and S. mitis as S. pneumoniae. Conclusions. These studies affirm the importance of applying reliable identification protocols for S. pneumoniae before serotyping; our protocols provide reliable diagnostic tools, as well as an improved workflow, for serotype identification of pneumococcus and differentiation of serogroup 6 types.
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| 29. |
- Grahn, Niclas, et al.
(author)
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Molecular identification of Helicobacter DNA present in human colorectal adenocarcinomas by 16S rDNA PCR amplification and pyrosequencing analysis
- 2005
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 54:11, s. 1031-1035
-
Journal article (peer-reviewed)abstract
- Seroepidemiological studies have indicated that Helicobacter pylori infection might be a possible risk factor for colorectal adenocarcinoma (CRC) development. However, limited information is available as to whether or not Helicobacter species are present in CRC tissues. In this study the presence of Helicobacter DNA in 77 CRC biopsies was investigated by means of a Helicobacter species-specific 16S rDNA PCR assay and real-time DNA pyrosequencing of the 16S rDNA variable V3 region. Pyrosequencing revealed the presence of Helicobacter DNA sequences in 21 of 77 biopsy specimens (27%). 16S rDNA sequences corresponding to H. pylori 26695 and H. pylori J99 were most commonly found. Intriguingly, one sequence belonged to Helicobacter mustelae, previously identified in ferrets. No significant correlations were found in the prevalence of Helicobacter DNA between colon and rectum tumour biopsies (P = 0.815), nor between Dukes' classes A/B and C/D (P = 0.262). 16S rDNA PCR amplification combined with pyrosequencing analysis of 16S rDNA variable V3 regions provides a powerful molecular tool to identify Helicobacter species in human biopsy specimens. © 2005 SGM.
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| 30. |
- Hedeland, Mikael, et al.
(author)
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Confirmation of botulism in birds and cattle by the mouse bioassay and Endopep-MS
- 2011
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 60:9, s. 1299-1305
-
Journal article (peer-reviewed)abstract
- There have been several outbreaks of botulism among poultry and wild birds in Sweden in recent years. The National Veterinary Institute of Sweden (SVA) has identified botulinum neurotoxin (BoNT)/C1 or the mosaic BoNT/C1D using the mouse bioassay. This is believed to be the first report on the application of the Endopep mass spectrometry (Endopep-MS) method to selected clinical animal (serum and liver) samples and a feed sample that had previously given positive test results with the mouse bioassay. In the mouse bioassay eight of the eleven samples were found to be neutralized by both BoNT/C1 and /D antitoxins; the other three were neutralized only by BoNT/C1 antitoxin, but the mice showed a prolonged survival time when the samples had been treated with /D antitoxin. The Endopep-MS analysis, on the other hand, demonstrated only BoNT/C1 activity for all eleven samples. This suggests that at least eight of the samples were of the chimeric toxin type BoNT/C1D, where the enzymically active site is identical to that of BoNT/C1, while other parts of the protein contain sequences of BoNT/D. This is the first step of a cross-validation between the established mouse bioassay and the Endopep-MS of serotypes BoNT/C1 and /C1D. Endopep-MS is concluded to have potential as an attractive alternative to the mouse bioassay.
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| 31. |
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| 32. |
- Isaksson, Jenny, et al.
(author)
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Lymphogranuloma venereum rates increased and Chlamydia trachomatis genotypes changed among men who have sex with men in Sweden 2004-2016
- 2017
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 66:11, s. 1684-1687
-
Journal article (peer-reviewed)abstract
- This study aimed to determine the incidence of lymphogranuloma venereum (LGV) in Sweden since 2004 and to study in detail a consecutive number of Chlamydia trachomatis cases in men who have sex with men (MSM) during a 10 month period (September 2014 to July 2015). LGV increased from sporadic import cases in 2004 to comprise a spread within Sweden in 2016. Initially, only the L2b ompA genotype was detected, but in 2015 half of the genotyped LGV cases were L2 genotype. The changing genotype distribution in Sweden is linked to increased LGV spread in Europe. High-resolution multilocus sequence typing of 168 C. trachomatis cases from MSM in 2015 resulted in 29 sequence types, of which 3 accounted for 49% of cases. The increased rates and different genotypes of LGV indicate that more concern for high-risk taking MSM is needed to avoid further spread of this invasive infection.
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| 33. |
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| 34. |
- Jansson, D. S., et al.
(author)
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Brachyspira hyodysenteriae and other strongly beta-haemolytic and indole-positive spirochaetes isolated from mallards (Anas platyrhynchos)
- 2004
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 53:4, s. 293-300
-
Journal article (peer-reviewed)abstract
- The aims of the current study were to collect intestinal spirochaetes (genus Brachyspira) from farmed and wild mallards (Anas platyrhynchos) and to identify and classify those isolates that phenotypically resembled Brachyspira hyodysenteriae, an enteric pathogen of pigs. The isolation rate of Brachyspira spp. was high from both farmed (93%) and wild mallards (78%). In wild mallards, it appeared that Brachyspira spp. were more likely to be found in migratory birds (multivariate analysis: RR = 1(.)8, 95% Cl 1(.)1-3(.)1) than in mallards sampled in a public park. Pure cultures of putative B. hyodysenteriae were obtained from 22 birds. All five isolates from farmed mallards and ten randomly selected isolates with this phenotype were used for further studies. All isolates from farmed mallards and two of the isolates from wild mallards were PCR-positive for the tlyA gene of B. hyodysenteriae. Two isolates from farmed mallards were selected for pulsed field gel electrophoresis (PFGE) and randomly amplified polymorphic DNA (RAPD) analysis. These isolates clustered with the type and reference strains of B. hyodysenteriae. 16S rDNA sequence analysis performed on 11 of the strains showed that they were all closely related to each other and to the B. hyodysenteriae-Brachyspira intermedia cluster. Three of the mallard isolates had 16S rDNA sequences that were identical to those of B. hyodysenteriae strains R1 and NIV-1 previously isolated from common rheas (Rhea americana). To conclude, the isolates from farmed mallards and two isolates from wild mallards were classified as B. hyodysenteriae based on the factthat they could not be differentiated by any of the applied methods from type, reference and field strains of B. hyodysenteriae. The remaining isolates could not be assigned irrefutably to any of the presently recognized Brachyspira species. These results point to a broader host spectrum of B. hyodysenteriae than is generally recognized, and to the presence in mallards of strongly haemolytic and indole-producing spirochaetes that possess many, but not all, of the currently recognized characteristics of B. hyodysenteriae.
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| 35. |
- Johansson, K. E., et al.
(author)
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Identification of three clusters of canine intestinal spirochaetes by biochemical and 16S rDNA sequence analysis
- 2004
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 53:4, s. 345-350
-
Journal article (peer-reviewed)abstract
- It has been suggested that canine intestinal spirochaetes consist of Brachyspira pilosicoli and a group of strains that has been provisionally designated 'Brachyspira canis'. The purpose of the present study was to compare 22 spirochaete isolates that were obtained from intestinal specimens of dogs in Sweden (n = 12), Norway (n = 4), the United States (n = 3), Australia (n = 2) and Germany (n = 1) with type and reference strains, as well as field isolates, of Brachyspira species by five biochemical tests and determination of almost-complete 16S rDNA sequences. In an evolutionary tree derived from 16S rDNA sequences, the canine isolates grouped into three clusters. One cluster included the type strain of porcine B. pilosicoli, whereas a second larger cluster, which was monophyletic, contained a canine strain that was identified previously as 'B. canis'. The third cluster consisted of three canine isolates of Scandinavian origin, which grouped together with the type strain of the species Brachyspira alvinipulli (pathogenic to chicken). These three genotypes, which were identified on the basis of 16S rDNA sequences, corresponded to four phenotypic groups based on biochemical testing. Two biochemical tests, hippurate hydrolysis and alpha-galactosidase production, were sufficient for rapid identification of each canine cluster.
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| 36. |
- Jurstrand, Margaretha, et al.
(author)
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Detection of Mycoplasma genitalium in urogenital specimens by real-time PCR and by conventional PCR assay
- 2005
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 54:1, s. 23-29
-
Journal article (peer-reviewed)abstract
- A real-time LightCycler PCR (LC-PCR) with hybridization probesfor detection of Mycoplasma genitalium in endocervical and firstvoid urine specimens was developed and compared to a conventionalPCR. The primers for both assays were identical and designedto amplify a 427 bp fragment of the 16S rRNA gene of M. genitalium.The LC-PCR assay had a detection limit of < 5 bacterial genomesper reaction when dilutions of genomic DNA from a type strainof M. genitalium were tested. First void urine from 398 menand first void urine and endocervical specimens from 301 womenattending an STD clinic were analysed by LC-PCR and by the conventionalPCR. Using the conventional PCR as reference, the LC-PCR hada specificity of 99.7 % and a sensitivity of 72.2 % for thedetection of M. genitalium in first void urine samples frommen. There was no significant difference in the performanceof the LC-PCR assay compared to the conventional PCR when endocervicalswabs were considered (58 and 65 %, respectively) or with aset of endocervical swab/urine specimens for which the LC-PCRassay detected 73 % of the infections (specificity = 98.6 %and sensitivity = 68.2 %) while the conventional PCR detected85 % of the infections. With female urine specimens there wasa significant difference between the two assays (38 and 73 %,respectively; P = 0.01 McNemar's test). This illustrates theneed to analyse both endocervical and urine specimens, becauseM. genitalium DNA was detected in only one of the two specimensin a great number of the M. genitalium-infected women. The lowersensitivity of the LC-PCR assay was probably caused by a combinationof inhibition and limitations regarding the amount of templateDNA. The LC-PCR assay was easy to perform and the simultaneousamplification and detection eliminated the need for furtherhandling of PCR products. With improvement in sample preparationmethods and increased volumes of the template DNA, the LC-PCRassay could be a useful routine diagnostic method.
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| 37. |
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| 38. |
- Katouli, Mohammad, et al.
(author)
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Selective translocation of coliform bacteria adhering to caecal epithelium of rats during catabolic stress
- 1997
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In: Journal of Medical Microbiology. - : The Microbiology Society. - 0022-2615 .- 1473-5644. ; 46:7, s. 571-578
-
Journal article (peer-reviewed)abstract
- Adult conventional rats were starved for 48 h with or without haemorrhage at 24 h, and translocation of caecal coliforms to mesenteric lymph nodes (MLNs) was measured. Translocation was detected in three of 11 rats without haemorrhage, in 6 of 11 starved and sham-operated rats and in 12 of 22 rats after haemorrhage. In contrast, only one of 13 non-instrumented and fed control rats showed translocation. Translocation was associated with more coliforms adhering to caecal epithelium in rats. Coliform isolates from caecum, caecal epithelium and MLNs were characterised and grouped into different biochemical phenotypes (BPTs) by a biochemical fingerprinting method. Of 291 BPTs detected in the caecum of all rats, 108 were also found on caecal epithelium; 36 BPTs were detected in MLNs, of which 17 were not detected either in the caecum or on the caecal epithelium of the corresponding rats. One isolate from each of these 36 BPTs was selected and compared to the others. Four common (C) BPTs (i.e., C1-C4) were identified among them. Strains of C1 formed the majority of isolates from the caecum (79%), caecal epithelium(71%) and MLNs (91%). In contrast, C2-C4 had a significantly lower incidence both in the caecum and on the caecal epithelium, but not in the MLNs. These findings indicate that not all caecal coliforms adhere to the epithelium during catabolic stress and that for translocation to occur, other bacterial properties besides adhesion are needed. It is also concluded that coliforms with a low incidence in the caecum can translocate with the same efficiency as those with a high incidence.
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| 39. |
- Kistler, J. O., et al.
(author)
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The oral microbiome in human immunodeficiency virus (HIV)-positive individuals
- 2015
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 64:Part: 9, s. 1094-1101
-
Journal article (peer-reviewed)abstract
- Human immunodeficiency virus (HIV) infection is associated with a range of oral conditions, and increased numbers of disease-associated microbial species have previously been found in HIV-positive subjects. The aim of this study was to use next-generation sequencing to compare the composition of the oral microbiome in HIV-positive and -negative individuals. Plaque and saliva were collected from 37 HIV-positive individuals and 37 HIV-negative individuals, and their bacterial composition determined by pyrosequencing of partial 16S rRNA genes. A total of 855 222 sequences were analysed. The number of species-level operational taxonomic units (OTUs) detected was significantly lower in the saliva of HIV-positive individuals (mean=303.3) than in that of HIV-negative individuals (mean=365.5) (P<0.0003). Principal coordinates analysis (PCoA) based on community membership (Jaccard index) and structure (Yue and Clayton measure of dissimilarity) showed significant separation of plaque and saliva samples [analysis of molecular variance (AMOVA), P<0.001]. PCoA plots did not show any clear separation based on HIV status. However, AMOVA indicated that there was a significant difference in the community membership of saliva between HIV-positive and -negative groups (P=0.001). Linear discriminant analysis effect size revealed an OTU identified as Haemophilus parainfluenzae to be significantly associated with HIV-positive individuals, whilst Streptococcus mitis/HOT473 was most significantly associated with HIV-negative individuals. In conclusion, this study has confirmed that the microbial composition of saliva and plaque is different. The oral microbiomes of HIV-positive and -negative individuals were found to be similar overall, although there were minor but significant differences in the composition of the salivary microbiota of the two groups.
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| 40. |
- Larsson, Jenny, et al.
(author)
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Pathological and bacteriological characterization of neonatal porcine diarrhoea of uncertain aetiology
- 2015
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 64, s. 916-926
-
Journal article (peer-reviewed)abstract
- Neonatal porcine diarrhoea of uncertain aetiology has been reported from a number of countries. This study investigated 50 diarrhoeic and 19 healthy piglets from 10 affected Swedish herds. The piglets were blood-sampled for analysis of serum gamma-globulin and necropsied, and the intestines were sampled for histopathology and cultured for Escherichia coli, Clostridium perfringens and Clostridium difficile. Escherichia coli isolates (n=276) were examined by PCR for virulence genes encoding LT, STa, STb, EAST1, VT2e, F4, F5, F6, F18, F41, AIDA-I, intimin, and for the genes aaiC and aggR. Selected isolates were analysed for additional virulence genes by a microarray and subjected to O-typing. Clostridium perfringens isolates (n=152) were examined by PCR for genes encoding major toxins, enterotoxin and beta2-toxin. There was no difference in serum gamma-globulin concentration between diarrhoeic and non-diarrhoeic piglets, and pathological lesions in the intestines were generally mild. Porcine enterotoxigenic Escherichia coli, a common cause of piglet diarrhoea, was only found in two piglets. Further, the virulence gene profiling did not suggest involvement of other diarrhoeogenic pathotypes of Escherichia coli. Growth of Clostridium perfringens did not differ between diarrhoeic and non-diarrhoeic piglets. All isolates were type A, all were negative for enterotoxin, and 151 of 152 isolates were beta2-toxin positive. In pigs >= 2 days old, moderate to profuse growth of Clostridium difficile was more common in the controls. In conclusion, it was not possible to relate Escherichia coli, Clostridium perfringens type A and C or Clostridium difficile to neonatal porcine diarrhoea in any of the investigated herds.
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| 41. |
- Lindgren, Helena, et al.
(author)
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Factors affecting the escape of Francisella tularensis from the phagolysosome.
- 2004
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 53:10, s. 953-958
-
Journal article (peer-reviewed)abstract
- The highly virulent bacterium Francisella tularensis is well adapted to the intracellular habitat but the mechanisms behind its intracellular survival have been elusive. Recently, it was shown that the bacterium is capable of escaping from the phagosome of human and mouse monocytic cells. Here it is shown that this escape is affected by gamma interferon (IFN-gamma) treatment of mouse peritoneal exudate cells since in treated cells the proportion that escaped was significantly lower (80%) than in untreated cells (97%) as determined by transmission electron microscopy. By contrast, < 1% of mutant bacteria lacking expression of a 23 kDa protein denoted IglC were able to escape from the phagosome. Infection with the DeltaiglC strain complemented with the iglC gene resulted in 60% of the bacteria escaping from the phagosome. Whereas IFN-gamma treatment conferred a static effect on intracellular wild-type bacteria, the treatment had a bactericidal effect on the DeltaiglC strain. The results show that the activation status of infected cells affects the escape of F. tularensis from the phagosome. An even more profound effect on this escape is related to expression of IglC by F. tularensis. Its absence rendered the mutant bacteria incapable of escaping from the phagosome and of multiplying intracellularly.
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| 42. |
- Luca, Bogdan, et al.
(author)
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Molecular characterization of invasive and non-invasive Streptococcus pyogenes isolates from Romania.
- 2008
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 57:Pt 11, s. 1354-1363
-
Journal article (peer-reviewed)abstract
- In 2002, the Romanian National Reference Laboratory was invited to join the Strep-EURO project to study invasive Streptococcus pyogenes infections. During 2003 and 2004, a total of 33 isolates recovered from invasive disease were received from eight Romanian counties. For comparison, 102 isolates from non-invasive disease, as well as a collection of 12 old invasive strains (isolated between 1967 and 1980) were included. All isolates were characterized by several methods: T and emm typing, presence of the fibronectin-binding protein F1 gene (prtF1), serum opacity factor (sof), and superantigen (SAg) genes (speA, speB, speC, speF, speG, speH, ssa and smeZ). The recent invasive isolates exhibited 19 emm-types, of which emm1, emm81, emm76, emm49 and emm78 covered 57 % of the strains. Furthermore, multilocus sequence typing analysis revealed nine new sequence types, corresponding to emm types 1, 12, 49, 81, 92, 100, 106 and 119. The non-invasive isolates comprised 24 different emm types with a predominance of emm1 and 12; the old invasive strains were of eight emm types, of which four were unique for this group. All isolates harboured speB and speF; smeZ was detected in all invasive strains, except for the emm49 and emm81 isolates. The majority of isolates from carriers, and patients with pharyngitis were prtF1 positive, most of these (14 strains) being emm12. High tetracycline resistance rates were noted among both invasive and control isolates (54 % and 35 %, respectively), whereas macrolide resistance rates were low (3 % and 5 %, respectively). Active and continuing surveillance is required to provide an accurate assessment of the disease burden and to provide epidemiological data on the character of isolates in Romania.
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| 43. |
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| 44. |
- Monstein, Hans-Jurg, 1946-, et al.
(author)
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Profiling of bacterial flora in gastric biopsies from patients with Helicobacter pylori-associated gastritis and histologically normal control individuals by temperature gradient gel electrophoresis and 16S rDNA sequence analysis
- 2000
-
In: Journal of Medical Microbiology. - 0022-2615 .- 1473-5644. ; 49:9, s. 817-822
-
Journal article (peer-reviewed)abstract
- The aim of this study was to establish bacterial profiles in gastric biopsy specimens from patients with Helicobacter pylori-associated gastritis by means of temporal temperature gradient gel electrophoresis (TTGE) of PCR-amplified 16S rDNA fragments. Specimens from eight patients with asymptomatic gastritis and five histologically normal controls revealed a Helicobacter-specific band in the TTGE profile with increased amounts of Helicobacter-specific DNA in the biopsies from most of the gastritis patients. DNA from other genera including Enterococcus, Pseudomonas, Streptococcus, Staphylococcus and Stomatococcus was also found in the stomach. In the absence of gastric inflammation, Helicobacter spp. appeared to be part of a complex, presumably indigenous microbial flora found in the biopsy specimens from the stomach.
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| 45. |
- Månsson, Emeli, 1978-, et al.
(author)
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Genomic relatedness of Staphylococcus pettenkoferi isolates of different origins
- 2017
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 66:5, s. 601-608
-
Journal article (peer-reviewed)abstract
- Purpose: The aim of the study was to characterize clinical and environmental Staphylococcus pettenkoferi isolates with regard to genomic diversity and antibiotic susceptibility pattern. Repetitive-sequence-based PCR and core genome phylogenetic analysis of whole-genome sequencing (WGS) data verified the presence of distinct clades comprising closely related S. pettenkoferi isolates from different geographical locations and origins.Methodology: Phylogenetic relationships between 25 S. pettenkoferi isolates collected from blood cultures and intra-operative air sampling were determined by repetitive-sequence-based PCR typing and analysis of similar to 157 000 SNPs identified in the core genome after WGS. Antibiotic susceptibility testing and tests for biofilm production (microtitre plate assay) were performed.Results: Repetitive-sequence-based PCR as well as WGS data demonstrated the close relatedness of clinically significant blood culture isolates to probable contaminants, as well as to environmental isolates. Antibiotic-susceptibility testing demonstrated a low level of antimicrobial resistance. The mecA gene was present in two cefoxitin-resistant isolates. No isolates were found to produce biofilm.Conclusion: Close genomic relatedness of S. pettenkoferi isolates from different geographical locations and origins were found within clades, but with substantial genomic difference between the two major clades. The ecological niche of S. pettenkoferi remains unconfirmed, but the presence of S. pettenkoferi in the air of the operating field favours the suggestion of a role in skin flora. Identification of S. pettenkoferi in clinical samples should, in a majority of cases, most likely be regarded as a probable contamination, and its role as a possible pathogen in immunocompromised hosts remains to be clarified.
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| 46. |
- Nilsson, Ingrid, et al.
(author)
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Increased prevalence of seropositivity for non-gastric Helicobacter species in patients with autoimmune liver disease
- 2003
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 52:11, s. 949-953
-
Journal article (peer-reviewed)abstract
- Various Helicobacter species have been isolated from the stomach, intestinal tract and liver of a variety of mammalian and some avian species, and Helicobacter DNA has been detected in human bile and liver samples. An immunoblot assay was established to analyse serum antibody responses to non-gastric Helicobacter species in patients with autoimmune liver diseases, in comparison with healthy individuals. Sera from 36 patients with primary sclerosing cholangitis (PSC), 21 with primary biliary cirrhosis, 19 with autoimmune chronic hepatitis and 80 blood donors were analysed by immunoblot, using cell-surface proteins from Helicobacter pullorum, Helicobacter bilis and Helicobacter hepaticus as antigens. Prior to testing, sera were cross-absorbed with a whole-cell lysate of Helicobacter pylori. Antibody reactivity to various proteins of these three Helicobacter species was measured by densitometric scanning and results were processed by computer software to estimate antigenic specificity. Results were also compared with antibody response to H. pylori. For H. pullorum, reactivity to at least two of the proteins with molecular masses of 48, 45, 37, 20 and 16 kDa, for H. hepaticus, reactivity to the 76, 30 and 21 kDa proteins and for H. bilis, reactivity to the 22 and 20 kDa proteins, seemed to have high specificity. Positive immunoblot results with sera from patients with PSC to antigens of H. pullorum, H. bilis and H. hepaticus were found in 38, 22 and 25 of cases, respectively, and from patients with other autoimmune liver diseases, in 30, 22 and 22 of cases, respectively. Prevalence of serum antibodies to non-gastric Helicobacter species was significantly higher in patients with autoimmune chronic liver diseases than in healthy blood donors (P < 0.001). Increased antibody levels to enterohepatic Helicobacter species raise questions concerning an infectious role of these emerging bacterial pathogens in human autoimmune liver diseases.
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| 47. |
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| 48. |
- Paul-Satyaseela, M, et al.
(author)
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Immunoproteomics of Actinobacillus actinomycetemcomitans outer-membrane proteins reveal a highly immunoreactive peptidoglycan-associated lipoprotein.
- 2006
-
In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 55:7, s. 931-942
-
Journal article (peer-reviewed)abstract
- In a search for novel bioactive cell surface structures of periodontal pathogens, it was found that sera from two patients with Actinobacillus actinomycetemcomitans-associated infections reacted strongly at 17 kDa on immunoblots of A. actinomycetemcomitans outer-membrane protein (OMP) preparations. The 17 kDa antigen was also recognized by anti-CsgA (Escherichia coli curli major subunit) antibody. The 17 kDa A. actinomycetemcomitans protein was identified as peptidoglycan-associated lipoprotein (PAL; AaPAL) by two-dimensional immunoblotting and subsequent sequence analysis by mass spectrometry and bioinformatics tools. AaPAL was an OMP and a lipoprotein, and it had an OmpA-like domain. In a group of middle-aged subjects (n = 26), serum reactivity to AaPAL was associated with the presence of periodontitis but not with the oral detection of A. actinomycetemcomitans. Both human sera and rabbit antisera against three different types of antigens, the gel-purified AaPAL, A. actinomycetemcomitans whole-cell antigens, and CsgA, recognized putative PALs of oral haemophili in addition to AaPAL. The results demonstrated that the novel AaPAL is a conserved bacterial lipoprotein. It is expressed in vivo and is strongly immunoreactive. The antigenic cross-reactivity found between AaPAL and oral haemophili may enhance local and systemic immuno-inflammatory reactions in periodontitis.
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| 49. |
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| 50. |
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