Study On The Aac (6')-aph(2") Gene And The Multi-resistance In High-level Gentamicin-resistant Enterococcus

Objective To investigate the positive ratio of the drug resistance gene aac (6')-aph(2")in high-level gentamicin-resistant Enterococcus.To discuss the relationship between the drug resistance gene and the multi-resistance in high-level gentamicin-resistant enterococcus.Methods MIC tests were performed to detect the antibiotic resistance status in the clinic high-level gentamicin-resistant Enterococcus isolates that had been idengtified by Vitek-2.The drug resistance gene aac(6')-aph(2")was detected by PCR method and confirmed by sequencing.The statistical dependence between drug resistance gene and the multi-resistance was analyzed with exact propability.Results Totally 89 clinical strains of enterococcus were isolated,the isolation ratio of E.faecium,E.faecalis and other kind of enterococcus were 59.6%,32.6%.7.8%.The ratio of HLGRE was 75.6%(62/82).Among the HLGRE,there were 41 faeciums and 21 faecalises.There were striking dissimilarity between the resistance ratios of E.faecuim and that of E.faecalis to penicillin,ampcillin,ciprofloxacin (P＜0.05).Resistance ratios of E.faecalis to penicillin,ampcillin,ciprofloxacin were 37.9%,37.9%,27.6%,respectively.They were lower than E.faecium (94.3%,94.3%,90.6%).Resistance ratio of E.faecium to quinupristin-dalfopristin was 0%.It was lower than E.faecalis(96.6%).The resistance ratios of HLGR E.faecium were higher than the non-HLGR E.faecium to penicillin,ampcillin,ciprofloxacin,erythromycin,chloramphenicol,rifampin,nitrofurant oin,gentamicin,high-level gentamicin.There were marked difference between the resistance ratios of HLGR E.faecium and that of non-HLGR E.faecium to ciprofloxacin,gentamicin,high-level gentamicin(P＜0.05).The resistance ratios of HLGR E.faecalis were higher than the non-HLGR E.faecalis to erythromycin,ciprofloxacin,rifampin,gentamicin,high-level gentamicin. The positive ratio of aac(6')-aph(2")was 96.8%(60/62).The gene was detected in 66.1%(41/62)E.faecium and30.7%(21/62)E.faecalis.Among the non-HLGR enterococcus,the positive ratio of aac(6')-aph(2")was 50%.The DNA sequencing of 8 PCR products were consistent with it in the Genbank(99%-100%). Resistance ratio of aac(6')-aph(2")positive HLGR enterococcus was higher than that of aac(6')-aph(2")negative non-HLGR enterococcus(P＜0.05).aac (6')-aph(2")correlated with HLGRE and the multi-resistance of HLGRE (r=0.5683;r=0.7013).Conclusion The multi-resistant status of HLGRE in the first affiliated hospital of Kunming medical college is severe.The multi-resistant ratio of aac (6')-aph(2")positive strains and aac(6')-aph(2")negative strains had significant difference.There was statistical dependence between the aac(6')-aph(2")gene and the multi-resistance of HLGRE.