| 1. |
- Claesson, Carina, 1970-, et al.
(författare)
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Molecular typing and detection of the aap and atlE genes and ica operon in multi-drug resistant and susceptible coagulase negative staphylococci
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The aims of the present study were to identify clinical isolates of multidrug resistant (MDR) and susceptible coagulase negative staphylococci (CoNS), (n=76) to the species level by rpoB amplicon sequencing and to detect and compare the presence of the atlE and aap genes and the ica operon between MDR (n=26) and susceptible (n=27) Staphylococcus epidermidis isolates. Detection of the atlE and aap genes and ica operon was carried out using PCR amplification. Most of the isolates were S. epidermidis, both among the MDR and susceptible CoNS. Staphylococcus haemolyticus was the only other species found in the MDR group. All MDR and 96% of the susceptible S. epidermidis isolates carried the atlE gene. The ica operon was present in about 30% of both the MDR and susceptible S. epidermidis isolates. By comparison, aap gene carriage was more common among susceptible S. epidermidis isolates (44%) than the MDR S. epidermidis isolates (27%). The atlE gene was the only gene that was found alone in the S. epidermidis genome. About 25% of the S. epidermidis isolates carried the atlE and aap genes and the ica operon simultaneously. In conclusion, rpoB gene amplicon sequencing is an easy and reliable method to identify CoNS isolates at the species and subspecies level. Both MDR and susceptible S. epidermidis isolates were found to be well equipped with adhesion and aggregation genes which might help them to adhere to artificial surfaces, colonize hospitalised patients and cause biofilm-related infections.
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| 2. |
- Claesson, Carina, 1970-
(författare)
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Staphylococci and Enterococci : Studies on activity of antimicrobial agents and detection of genes involved in biofilm formation
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The Gram-positive cocci, Staphylococcus aureus, coagulase negative staphylococci (CoNS), Enterococcus faecalis and Enterococcus faecium, are the bacteria most often isolated from patients with hospital acquired infections. S. aureus is one of the most important pathogens and have a variety of virulence mechanisms which help it to infect the patient and cause tissue damage. CoNS and enterococci are low virulent bacteria and predominantly cause infections in individuals with underlying illness, individuals that have undergone surgery or with suppressed immune-system. The aims of this thesis were i) to investigate the susceptibility to different antimicrobial agents among S. aureus, CoNS, E. faecium and E. faecalis isolates from primary care centres, general hospital wards and intensive care units in Denmark, Finland, Norway and Sweden and ii) to study the prevalence of the cytolysin genes and genes involved in biofilm formation among CoNS, E. faecium and E. faecalis. The results in this thesis show that the resistance rates among S. aureus and E. faecalis is still rather low in the north European countries. Among CoNS and E. faecium resistance rates are higher and comparable with rates in other European countries and US. CoNS had statistically significant differences in susceptibility rates between the ward levels with the lower susceptibility rates found at ICUs. Continued surveillance of resistance rates to antimicrobial agents among both staphylococci and enterococci are important internationally, nationally and locally. The results in this thesis also show that all multidrug resistant and 96% of the susceptible CoNS isolates carried at least one of the atlE and aap genes or the ica operon. Among E. faecalis isolates with HLGR, belonging to a cluster of genetically related isolates, both the esp and asa1 genes were carried in a high degree while the cyl operon was less frequently found. In addition, about 30% of unique E. faecalis isolates carried two or more of the virulence genes. Among E. faecium isolates the esp gene was common but asa1 and the cyl operon was not found in any of the isolates. Both CoNS and E. faecalis isolates from hospitalised patients are well equipped with genes involved in biofilm formation. These genes, when expressed and even more in combination with resistance to antimicrobial agents, might give these isolates an advantage compared to other isolates when it comes to adhesion to artificial surfaces, persistence in the hospital environment, colonisation of hospitalised patients and to cause nosocomial infections. Further studies are needed to be able to determine which isolates that causes hospital acquired infections and to evaluate the importance of the genes involved in biofilm formation as virulence factors and about how to prevent biofilm related infections from emerging
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| 3. |
- Evertsson, U, et al.
(författare)
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Detection and identification of fungi in blood using broad-range 28S rDNA PCR amplification and species-specific hybridisation
- 2000
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Ingår i: Acta Pathologica, Microbiologica et Immunologica Scandinavica (APMIS). - 0903-4641 .- 1600-0463. ; 108:5, s. 385-392
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to develop a PCR-based method to detect and identify fungi directly from human venous blood. We used broad-range PCR primers that targeted a part of the large subunit 28S rRNA genes. To obtain species-specific hybridisation probes, type strains of Candida albicans, C. glabrata, C. krusei, C. parapsilosis, C. tropicalis and Cryptococcus neoformans were PCR amplified, and the amplicons were analysed by gene sequencing. Based on the sequence analysis, species-specific probes that targeted variable regions were designed and used in hybridisation analyses. Between 2 to 10 fungal cells/ml of spiked blood samples could be detected and correctly identified to species. We applied the technique to blood samples obtained from two patients with or two patients without verified candidaemia. The three samples of candidaemia patients were correctly identified to species level, and those of the negative patients remained negative. This method is a potential tool for diagnosis of systemic invasive candidiasis.
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| 4. |
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| 5. |
- Grahn, Niclas, et al.
(författare)
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Identification of mixed bacterial DNA contamination in broad-range PCR amplification of 16S rDNA V1 and V3 variable regions by pyrosequencing of cloned amplicons
- 2003
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Ingår i: FEMS Microbiology Letters. - 0378-1097 .- 1574-6968. ; 219:1, s. 87-91
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Tidskriftsartikel (refereegranskat)abstract
- Using a sensitive and rapid method combining broad-range PCR amplification of bacterial 16S rDNA fragments and pyrosequencing for detection, identification and typing, we have found contaminating bacterial DNA in our reagents used for PCR. Identified bacteria are the water-borne bacterial genera Pseudomonas, Stenotrophomonas, Xanthomonas, Ralstonia and Bacillus. Our results are in concordance with recent reports of contaminated industrial water systems. In light of this conclusion, we believe that there is a need for increased awareness of possible contamination in uncertified widely used molecular biology reagents, including ultra-pure water. Since sequence-based 16S rDNA techniques are used in a variety of settings for bacterial typing and the characterization of microbial communities, we feel that future certification of molecular biology reagents, as free of nucleic acids, would be advantageous. ⌐ 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.
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| 6. |
- Grahn, Niclas, et al.
(författare)
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Molecular identification of Helicobacter DNA present in human colorectal adenocarcinomas by 16S rDNA PCR amplification and pyrosequencing analysis
- 2005
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Ingår i: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 54:11, s. 1031-1035
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Gustavsson, O., et al.
(författare)
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A wide spectrum of fastidious and ampicillin-susceptible bacteria dominate in animal-caused wounds
- 2016
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Ingår i: European Journal of Clinical Microbiology & Infectious Diseases. - : Springer Science and Business Media LLC. - 0934-9723 .- 1435-4373. ; 35:8, s. 1315-1321
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Tidskriftsartikel (refereegranskat)abstract
- The main purpose of this study was to assess the actual occurrence of Gram-negative oxidase-positive bacteria (GNOP) in human wounds caused by animals, mostly cat and dog bites and scratches, and with signs of infection. We report a prospective series of 92 wound samples. Routine culturing was combined with a procedure optimised for fastidious GNOP. All GNOP isolates were identified by 16S rDNA sequencing to the species level. We observed a more prominent role of GNOP, including at least 30 species mostly in the families Flavobacteriaceae, Neisseriaceae and Pasteurellaceae, and less of Staphylococcus aureus and streptococci. The antibiotic susceptibility pattern was investigated, as GNOP are associated with sudden onset of serious infections, making an early decision on antibiotic treatment vital. All GNOP isolates judged to be clinically relevant displayed susceptibility to ampicillin and meropenem, but resistance to oxacillin, clindamycin and gentamicin was frequent. Our findings emphasise the need to cover GNOP as recommended in guidelines, and not only common wound pathogens, when treating an animal-caused wound.
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| 8. |
- Hällgren, Anita, et al.
(författare)
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Frequency of aggregation substance, cytolysin and enterococcal surface protein in vitro adhesion to urinary catheters of E. faecalis and E. faecium of clinical origin
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Enterococcal isolates, 21 E. faecium and 94 E. faecalis, isolated from blood cultures, rectal specimens and various other clinical samples were examined for the presence of the virulence factors hemolysin/cytolysin, aggregation substance (asa1) and enterococcal surface protein (esp). The isolates were previously characterized by pulsed-field gel electrophoresis (PFGE). Adhesion to siliconized latex urinary catheters was analysed in 14 clinical isolates and 3 control strains. Densities of adhering bacteria were determined by a bioluminescence assay of bacterial ATP. The only virulence factor found in E. faecium, esp, was found in 71% of the 21 E. faceium isolates. Cytolysin production, asa1 and esp were found in 13%, 79% and 73%, respectively, of the 94 E. faecalis isolates. Isolates belonging to a cluster of genetically related isolates differed significantly with respect to carriage of esp and asa1 compared to unique isolates, with the virulence factors more commonly found among clustered isolates (p<0.01). No difference was found with respect to cytolysio production (p = 0.76). E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared (p = 0.38 and 0.64).
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| 9. |
- Hällgren, Anita, 1963-, et al.
(författare)
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Genetic relatedness among Enterococcus faecalis with transposon-mediated high-level gentamicin resistance in Swedish intensive care units
- 2003
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Ingår i: Journal of Antimicrobial Chemotherapy. - : Oxford University Press (OUP). - 0305-7453 .- 1460-2091. ; 52:2, s. 162-167
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Tidskriftsartikel (refereegranskat)abstract
- We studied 45 isolates of Enterococcus faecalis with high-level gentamicin resistance (HLGR), all but one concomitantly resistant to ciprofloxacin, and 25 ciprofloxacin-resistant isolates without HLGR for genetic relatedness using pulsed-field gel electrophoresis (PFGE). E. faecalis were isolated from patients admitted to intensive care units at eight hospitals in southern Sweden from December 1996 through December 1998. Genomic analysis by PFGE resulted in three clusters of genetically related isolates (designated clusters I, II and III) and 23 unique clones. Cluster I was found predominantly in the eastern and central parts of southern Sweden and clusters II and III in south-western Sweden. Among the 45 isolates with HLGR, 69% belonged to cluster I, 20% to cluster II, and 11% had unique PFGE patterns, which suggests that the majority of isolates with HLGR are closely related. Among the 25 ciprofloxacin-resistant isolates without HLGR, 68% had unique PFGE patterns, 12% belonged to cluster I and 20% to cluster III, which suggests the ciprofloxacin-resistant isolates are not related. All isolates with HLGR contained the aac(6′)Ie-aph(2″)Ia gene, which was carried on a Tn5281-like transposon in all isolates except one. We conclude that HLGR in E. faecalis was mainly due to dissemination of genetically related clones during the time studied, and that HLGR in these isolates was due to the presence of the aac(6′)Ie-aph(2″)Ia gene.
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| 10. |
- Hällgren, Anita, et al.
(författare)
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Molecular detection of aggregation substance, enterococcal surface protein, and cytolysin genes and in vitro adhesion to urinary catheters of Enterococcus faecalis and E. faecium of clinical origin
- 2009
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Ingår i: International Journal of Medical Microbiology. - : Elsevier BV. - 1438-4221 .- 1618-0607. ; 299:5, s. 323-332
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Tidskriftsartikel (refereegranskat)abstract
- It has been hypothesized that nosocomial enterococci might have virulence factors that enhance their ability to colonise hospitalised patients. The objectives of this study were to investigate the prevalence of genes encoding 3 virulence factors: aggregation substance (asa1), enterococcal surface protein (esp), and 5 genes within the cytolysin operon (cylA, cylB, cylM, cylL(L), cylL(S)) and cytolysin production in 115 enterococcal clinical isolates (21 Enterococcus faecium and 94 E. faecalis). Adhesion to siliconized latex urinary catheters in relation to presence of esp was analysed in a subset of isolates. The isolates were previously characterised by pulsed-field gel electrophoresis (PFGE). esp was the only virulence gene found in E. faecium. It was found in 71% of the 21 E. faecium isolates. asa1, esp, and the cyl operon were found in 79%, 73% and 13% respectively, of the 94 E. faecalis isolates. There was a complete agreement between presence of the cyl operon and phenotypic cytolysin production. Isolates belonging to a cluster of genetically related isolates carried esp and asa1 more often when compared to unique isolates. No difference was found with respect to cyl genes. E. faecalis isolates adhered with higher bacterial densities than E. faecium. E. faecalis isolates within the same PFGE cluster adhered with similar bacterial densities, but there was no association between adhesion and the presence of esp when isolates within the same cluster were compared. In conclusion, E. faecalis isolates with high-level gentamicin resistance (HLGR) belonging to clusters of genetically related isolates widely distributed in Swedish hospitals, were likely to carry both esp and asa1. Adhesion was not affected by esp.
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