Bacteria resistance surveillance on Enterococci Isolated from pedlatric hospitals and distribution of resistance genes ermB,mefA,tetM and the integrase gene intTn of Tn1545 in Enterococci / 中华检验医学杂志

ABSTRACT

Objective To determine the drug-resistance rate of Enterococci isolated from patients of 5 padiatric hospitals located at different areas in China,and to investigate the distribution of resistance genes ermB,mefA,tetM and the integrase gene intTn of Tn1545 in Enterococci.Methods The antimicrobial susceptibility to 8 antibiotics of 2 216 Enteroeocei isolates was determined.PCR was used to detect the macrolide resistance genes ermB and mefA,tetracycline resistance genes tetM,and the integrase gene int-Tn of Tn1545.Results The resistance rates to erythromycin,ampicillin,gentamicin and teicoplanin were 86.5%,48.0%,60.5% and 0.7%,respectively.All isolated Enterococci straim were found sensitive to vancomycin.Of the detected 225 strains,70.7% of the 225 detected strains carried ermB gene while 75.1% of them carried tetracycline resistance gene tetMonly one strain had mefA.The presence of ermB gene in erythromycin MIC＞256 mg/L straim group(95.7%)strains was higher than those in erythromycin MIC＜256 mg/L group(2.5%).The int-Tn gene was detected in 40.9%(92/225)of the 225 test strains.The presence of ermB gene in int-Tn positive group strains was higher(84.8%)than those in int-Tn negative strains group(60.9%).So did the tetM in int-Tn positive group(83.7%)compared with those in int-Tn negative group(70.0%).Conclusions Enterococci sbowed a high resistance rate to the antibiotics we monitored,especially to erythromycin;but still very senstive to glycopeptide antibiotics. Resistance to macrolide in Enterococci collected from clinical in five Children's Hospital was generally mediated by methylation of 23S rRNA via ermB methylase. Enterococci resistance to tetracycline was predominantly due to ribosomal protection encoded by tetM. There was a strong relationship of the ermB and tetM genes with Tn1545-related elements.