Screening for resistance encoding integrons in isolates of Enterococci

Abstract

BACKGROUND: Integrons are bacterial genetic elements, working as assembly platforms, by incorporating gene cassettes (GCs) in the bacterial genome. 130 GCs providing antimicrobial resistance to most classes of antibiotics have been described, and most of them are associated with the class 1 integrons. Class 1 integrons are widespread among clinically important Gram-negatives, but are rare in gram positives. Recently, the first detection of integrons in clinical isolates of enterococci was described. Over the last two decades enterococci has emerged as one of the leading causes to nosocomial infections world over, as a result of development of hospital adapted lineages. These lineages tend to possess genes encoding antimicrobial resistance and have increased virulence. It is therefore of great interest to search for integrons in enterococci, as acquisition of integrons in enterococci could lead to an even more critical situation in the treatment of enterococcal infection. MATERIAL AND METHODS: A diverse collection of 274 enterococcal isolates was screened by IntI1 PCR which is a good marker for presence of class 1 integrons. Additionally, 24 of the isolates were further examined by colony blot hybridization and antibiotic susceptibility testing. RESULTS: All isolates were found to be PCR negative for the IntI1 integrase. Two possible positive results were detected by colony blot hybridization. CONCLUSION: Presence of Class 1 integrons was not detected in the enterococci-isolate collection investigated. However, further investigation of two possible positive isolates is required to verify the results. Moreover the whole isolate collection should additionally be investigated by hybridisation techniques before a conclusion of the findings can be made.