肠球菌耐药特征及对高浓度庆大霉素耐药基因的研究

Investigation on the antimicrobial resistance pattern and high-level gentamicin resistance genes in Enterococci

目的 研究从临床标本中分离到的303株肠球菌的耐药特征,以及了解我院庆大霉素高浓度耐药肠球菌耐药基因的流行分布。方法 细菌鉴定和抗生素药敏试验采用Vitek 32全自动微生物系统自动分析,运用PCR方法检测acc(6’) Ie aph(2”) Ia,aph(2”) Ib和aph(2”) Ic基因;并对部分PCR扩增产物DNA测序分析。结果 303 株肠球菌中以粪肠球菌和屎肠球菌最多见,分别占72.6%和22.4%;对庆大霉素高浓度耐药的粪肠球菌和屎肠球菌分别为57.9%和66.7%;对链霉素高浓度耐药粪肠球菌和屎肠球菌分别为52.6%和33.3%;对145株肠球菌进行高浓度庆大霉素耐药基因的检测显示:acc(6’) Ie aph(2”) Ia基因是高浓度庆大霉素耐药肠球菌的惟一耐药基因,未检测到aph(2”) Ib和aph(2”) Ic基因。结论 监测肠球菌属对高浓度氨基苷类抗生素的耐药情况和应用分子生物学技术检测高浓度庆大霉素耐药基因,为临床医师治疗肠球菌感染提供依据。

Objective To investigate the antimicrobial resistance pattern of 303 enterococccal isolates and detect the high-level gentamicin resistance genes to determine the prevalence of these genes. Methods Vitek-32 automatic microbial analysis system was used to identify the organisms and study the antimicrobial resistance. Polymerase chain reaction (PCR) was applied for detecting high-level gentamicin resistance genes aac(6’)-Ie-aph(2”)-Ia, aph(2”)-Ib and aph(2”)-Ic. Some suspected PCR products were confirmed by DNA sequencing.Results A total of 303 enterococcal isolates were collected, including 220 ( 72.6%) isolates of E.faecalis, 68 (22.4%) E.faecium, and 15 other Enterococcus (5.1%). High-level gentamicin resistance was found in 57.9% of E.faecalis and 66.7% of E.faecium respectively. High-level streptomycin resistance was found in 52.6% of E.faecalis and 33.3% of E.faecium respectively. One hundred and forty-five strains of Enterococcus were tested for the presence of high-level gentamicin resistance genes. Results showed that aac(6’)-Ie-aph(2”)-Ia was the only high-level gentamicin resistance gene detected, aph(2”)-Ib and aph(2”)-Ic were not detected.Conclusions Understanding the resistance pattern of high-level aminoglycoside resistance and applying molecular biological techniques to detect high-level gentamicin resistance genes in Enterococcus spp. are important for rational treatment of infections caused by Enterococcus.