Detection of ?-Lactamase and blaZ Gene of Ampicillin-resistant Enterococcus / 中华医院感染学杂志

ABSTRACT

OBJECTIVE To detect ?-lactamase of ampicillin-resistant Enterococcus in order to choose drugs for clinical treatment.METHODS According to CLSI's guideline,antimicrobial susceptibility tests were performedto detect ?-lactamase with nitrocefin,to detect blaZ by PCR and to detect mutation of pbp4 by single-strand conformation polymorphism(SSCP).RESULTS The resistant rates of E.faecium and E.faecalis to ampicillin,penicillin,high level gentamicin,high level streptomycin,levofloxacin,erythromycin,tetracycline,and chloramphenicol were 100%,100%;86%,76%;46%,44%;84%,74%;100%,94%;54%,58%;and 42%,36%;to rifampicin 62%,58%;and to vancomycin both 0%,respectively.The positive rate of ?-lactamase in 50 E.faecalis strains with paper disk method and test tube method was 8% and 26%;and that of blaZ by PCR was 88%.But in 50 E.faecium strains the results were 0% and 2%,respectively.There was no significant mutation by SSCP and sequencing in E.faecalis.CONCLUSIONS The positive rate to ?-lactamase in E.faecalis is markedly higher than in E.faecium.The method of PCR is better than that of nitrocefin.The positive rate of test tube method is higher than paper disk method with nitrocefin.