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- Mihaylova, Sashka A, et al.
(författare)
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Analyses of clinically-relevant isolates of Stenotrophomonas spp.
- 2007
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Ingår i: Proceedings of the 26th Annual General Meeting of the European Culture Collections’ Organization; A0264.
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Konferensbidrag (refereegranskat)abstract
- Objectives: The identification of clinical isolates of Stenotrophomonas spp. to the species level, using a polyphasic approach of phenotypic and genotypic methods, and the determination and comparison of the in vitro responses to various classes of antimicrobial agents by these isolates. Previous studies have suggested a marked diversity among clinical, as well as environmental, isolates of Stenotrophomonas spp. and they represent a significant threat within hospital settings, particularly for patients in ICUs and other immunocompromised conditions. Isolates characterised as putative Stenotrophomonas spp. from Pleven University Hospital were analysed in detail. The predominant source of the isolates was respiratory tract and two thirds of patients were admitted to ICUs. Isolates were examined, using the VITEK 2 compact system, CCUG phenotypic characterisation panels and sequencing and analyses of the genes for 16S rRNA and gyrB. The in vitro responses of isolates to 10 antibiotics (azlocillin, piperacillin, ceftazidime, imipenem, meropenem, ampicillin-sulbactam, piperacillin-tazobactam, gentamicin, amikacin and ciprofloxacin) were evaluated, using the disc diffusion method, according to guidelines of the Clinical and Laboratory Standards Institute. The commercial VITEK 2 system defined all isolates as S. maltophilia, with probabilities of identifications varying from 92 to 99%, and “good”, “very good” or “excellent” confidence. Results from conventional phenotypic testing confirmed identifications for isolates as S. maltophilia or S. rhizophila. DNA sequencing and analyses further defined the species affiliations of isolates of the genus Stenotrophomonas. Previous reports have indicated that Stenotrophomonas spp. exhibit resistance to a broad range of antibiotics. More than 90% of examined isolates were observed to be resistant to imipenem, meropenem and ampicillin-sulbactam, more than 80% were resistant to azlocillin, piperacillin and piperacillin-tazobactam. The only beta-lactam antibiotic with an indication of better activity was ceftazidime. Among the ten antimicrobial agents tested, ciprofloxacin demonstrated the highest activity, as evaluated by diameter zone of growth inhibition. Conclusions: The VITEK 2 compact system identified all isolates to the genus level. However, conventional phenotypic testing may be more effective for species differentiation. Analysis of DNA gene sequencing allows further precise taxonomic identification. Ciprofloxacin could be a drug of choice for therapy of infections caused by Stenotrophomonas spp.
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