山东省潍坊市农村人群海氏肠球菌恶唑烷酮类耐药基因流行情况研究

Prevalence of oxazolidinone resistance genes in Enterococcus hirae from rural population in Weifang,Shandong

目的了解农村地区无症状人群中氟苯尼考耐药海氏肠球菌的耐药性和恶唑烷酮类耐药基因cfr、optrA、poxtA的携带情况。方法对来自山东省潍坊市的12个村620份粪便样品,用氟苯尼考(10 mg/L)肠球菌培养基进行细菌分离,利用飞行时间质谱仪鉴定菌种,采用琼脂稀释法对15种抗生素进行药敏试验,PCR鉴定耐药基因,对poxtA阳性的海氏肠球菌进行脉冲场凝胶电泳(pulsed-field gel electrophoresis,PFGE)分析。结果共分离获得29株海氏肠球菌。所有海氏肠球菌均对四环素、克林霉素耐药,对氯霉素表现为高耐药率,但未检出氨苄青霉素、万古霉素、阿莫西林/克拉维酸耐药菌株,利奈唑胺耐药率为10.3%(3/29)。未检测到携带cfr的海氏肠球菌,optrA和poxtA检出率分别是86.2%(25/29)和17.2%(5/29)。聚类分析显示,5株poxtA阳性海氏肠球菌属于5种PFGE带型。结论山东潍坊市农村地区健康人群中,海氏肠球菌耐药情况严重,optrA和poxtA的携带率很高,呈现高度多态性,提示可能存在公共卫生隐患,应加强相关监测。

This study was designed to investigate the related drug resistance of florfenicol-resistant Enterococcus hirae and the prevalence of carriage of the cfr,optrA,and poxtA genes that cause linezolid resistance in asymptomatic people in a rural area.A total of 620 stool samples were collected from 12 villages in Weifang City,Shandong Province.The samples were cultured on enterococcus selective medium supplemented with 10 mg/L florfenicol.The bacteria were identified using a time-of-flight mass spectrometer.The agar dilution method was used to test the susceptibility to 15 antibiotics.All Enterococcus hirae isolates were screened for the presence of the cfr,optrA,and poxtA genes by PCR.Pulsed-field gel electrophoresis(PFGE)analysis was performed on poxtA-positive Enterococcus hirae.A total of 29 strains of Enterococcus hirae were isolated in this study.All strains were resistant to tetracycline and clindamycin,and showed a high rate of resistance to chloramphenicol,but no strains resistant to ampicillin,vancomycin,or amoxicillin/clavulanic acid were detected.Linezolid resistance was identified in 10.3%(3/29)of the isolates.Enterococcus hirae isolates carrying cfr were not detected.The rates of carriage of optrA and poxtA were 86.2%(25/29)and 17.2%(5/29),respectively.Cluster analysis showed that the 5 poxtA-positive Enterococcus hirea isolates belonged to five PFGE bands.Among healthy people in rural areas of Weifang City,Shandong,antibiotic resistance in Enterococcus hirae is a serious problem.The high rates of carriage of optrA and poxtA in different clones indicate a hidden danger to public health.