1例肺炎患者利奈唑胺耐药粪肠球菌定植规律研究

The colonization of linezolid-resistant Enterococcus fecalis infection in a pneumonia patient

目的研究1例肺部感染患者体内利奈唑胺耐药粪肠球菌株突变以及定植特点。方法从1例反复发作肺炎(1年内反复发作5次)的急性白血病患者的气管分泌物中分离出10株粪肠球菌株,菌株的MIC值通过E-test测定,经PCR扩增细菌4个拷贝23S r RNA基因V区基因,测序分析突变位点,通过脉冲场凝胶电泳(PFGE)观察分离菌株同源性。结果患者5次肺炎发作从气管分泌物中分离的10株粪肠球菌株均为利奈唑胺不敏感株(4株为中介耐药株,6株为耐药株),通过PCR和测序发现4株利奈唑胺中介耐药株含有1个拷贝23S r RNA基因V区G2424U突变,而利奈唑胺耐药菌株同时含有G2424U和G2576U双突变。通过PFGE分型检测提示10株粪肠球菌株具有同源性。通过肉汤稀释法鉴定这些菌株均对万古霉素敏感。结论利奈唑胺耐药粪肠球菌株可能长期定植于患者体内,并导致反复感染。

Objective To explore the characteristics of resistance mutations and colonization of Linezolid-resistant E.faecalis strains. Methods Ten E.ecalis strains isolated from the tracheal secretion of a acute leukemia patient suffered fromrecurrent pneumonia （recurrent pneumonia five times in a year ）. The minimum inhibitory concentrations （MICs） weredetermined by E-test method and the variations of 23S rRNA V region gene of Entemcoceus faecalis were detected by PCRsequencing. The homology of these strains were demonstrated PFGE. Results Ten Eaecalis strains were linezolidresistant strains （intermediate resistant strains and resistant strains）, only the G2424U mutation was detected in theintermediate resistant strains, both the G2424U and G2576U double mutants were detected in resistant strains. Ten E. [aecalisstrains with very high homology by PFGE genotyping. The sensitivity of all these strains to vancomycin was demonstrated bybroth maerodillution. Conclusion Linezolid-resistant enterocoecus recalls strain may conolized persistendy in vivo and leadto recurrent infection.