| 1. |
- Hasan, Badrul, et al.
(författare)
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Emergence of carbapenem-resistant Acinetobacter baumannii in hospitals in Pakistan
- 2014
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 63:1, s. 50-55
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Journal of medical microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 58:1Pt 1, s. 125-131
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Tidskriftsartikel (refereegranskat)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.
(författare)
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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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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 52:9, s. 765-771
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Amaya, E, et al.
(författare)
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Antibiotic resistance patterns of intestinal Escherichia coli isolates from Nicaraguan children
- 2011
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Ingår i: Journal of medical microbiology. - : Microbiology Society. - 1473-5644 .- 0022-2615. ; 60:2Pt 2, s. 216-222
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Tidskriftsartikel (refereegranskat)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.
(författare)
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T A microarray analysis of the murine macrophage response to infection with Francisella tularensis LVS
- 2006
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 55:8, s. 1023-1033
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Tidskriftsartikel (refereegranskat)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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| 10. |
- Ansaruzzaman, M., et al.
(författare)
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Characterization of enterotoxigenic Escherichia coli from diarrhoeal patients in Bangladesh using phenotyping and genetic profiling
- 2007
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Ingår i: J Med Microbiol. - : Microbiology Society. ; 56:2Pt 2, s. 217-222
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Forskningsöversikt (refereegranskat)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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