新生儿重症监护室早产儿肠球菌的鉴定及同源性分析

Identification and homology analysis of Enterococcus isolated from premature infants in neonatal intensive care unit

目的对北京协和医院新生儿重症监护室(neonatal intensive care units,NICU)早产儿定植和感染部位、环境及益生菌中分离出的肠球菌进行菌种鉴定及同源性分析。方法收集2017年6月1—10日NICU及益生菌制剂中分离出的肠球菌共11株,用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)进行菌种鉴定,采用微量肉汤稀释法测定临床常用抗菌药物的最低抑菌浓度(MIC),用多位点序列分型(MLST)及脉冲场凝胶电泳(PFGE)进行菌株同源性分析。结果 11株菌均为粪肠球菌,对氨苄西林、万古霉素、替考拉宁、呋喃妥因、氯霉素、左氧氟沙星、利奈唑胺等抗菌药物均表现为敏感,仅1株菌对四环素和红霉素耐药。11株粪肠球菌经PFGE分为a-d 4个克隆群,MLST分型分别为ST624、ST25、ST40及ST16,PFGE与MLST分型结果一致。结论此次NICU早产儿粪肠球菌定植或感染可能与益生菌制剂的使用及物表定植的粪肠球菌相关。

Objective To identify and analyze the homology of Enterococcus strains isolated from the sites of infection or colonization of Enterococcus in premature infants,the environment of ward and probiotics. Methods A total of 11 strains of Enterococcus were collected from neonatal intensive care unit（ NICU） and probiotic preparations during 1 to 10 June of 2017 in Peking Union Medical College Hospital,and identified by MALDI-TOF MS. The antimicrobial susceptibility test was performed by microdilution broth method.The homology of Enterococcus was analyzed by multilocus sequence typing（ MLST） and pulsed-field gel electrophoreses（ PFGE）. Results All of the 11 strains were Enterococcus faecalis which were sensitive to ampicillin,vancomycin,teicoplanin,nitrofurantoin,chloramphenicol,levofloxacin and linezolid. Only 1 strain was resistant to tetracycline and erythromycin. PFGE showed that the 11 strains were divided into 4 groups of cloning（ a,b,c and d）. MLST showed 4 groups,ST624,ST25,ST40 and ST16 were divided. The typing results of the two methods were consistent.Conclusion The Enterococcus faecalis colonization or infection of premature infants in NICU may be associated with the use of probiotic preparation and colonized Enterococcus faecalis on the surface of objects in the ward.