Thal L, Donabedian S, Robinson-Dunn B, Chow J W, Dembry L, Clewell D B, Alshab D, Zervos M J
Department of Medicine, Wayne State University, Detroit, Michigan, USA.
J Clin Microbiol. 1998 Nov;36(11):3303-8. doi: 10.1128/JCM.36.11.3303-3308.1998.
The purpose of this study was to evaluate the molecular relatedness of clinical isolates of glycopeptide-resistant Enterococcus faecium isolates collected from hospitals in Michigan. A total of 379 isolates used in this study were all vancomycin-resistant E. faecium isolates collected from 28 hospitals and three extended-care facilities over a 6-year period from 1991 to 1996. For the 379 isolates, there were 73 pulsed-field gel electrophoresis (PFGE) strain types. Within strain types, there were as many as six restriction fragment differences. Most isolates (70%) belonged to six strain types, which were designated M1 (36%), M2 (3%), M3 (18%), M4 (6%), M10 (4%), and M11 (3%). PFGE strain M1 was cultured from 135 patients in 13 hospitals during the period 1993 to 1996. Strain type M2 was cultured from 11 patients in two hospitals during the period 1991 to 1992 and was not observed after 1992. Strain type M3 was cultured from 70 patients in 10 hospitals during the period of 1994 to 1996. Both M4 and M10 were cultured from 23 patients in three hospitals and from 15 patients in two hospitals, respectively, during 1995 to 1996. M11 was cultured from 13 patients in four hospitals during 1996. A total of 23 of 28 hospitals had evidence of clonal dissemination of some isolates. Plasmid content and hybridization analysis done on 103 isolates from one hospital and two affiliated extended-care facilities indicated that the strains contained from one to eight plasmids. Mating experiments indicated transfer of vancomycin resistance from 94 of these isolates into plasmid-free E. faecium GE-1 at transfer frequencies of <10(-9) to 10(-4). Gentamicin resistance and erythromycin resistance were cotransferred at various frequencies. A probe for the vanA gene hybridized to the plasmids of 23 isolates and to the chromosomes of 72 isolates. A probe for the vanB gene hybridized to the chromosomes of 8 isolates. The results of this study suggest inter- and intrahospital dissemination of vancomycin-resistant E. faecium strains over a 6-year period in southeastern Michigan. The majority of isolates studied belonged to the same few PFGE strains, indicating that clonal dissemination was responsible for most of the spread of resistance that occurred.
本研究的目的是评估从密歇根州医院收集的耐糖肽屎肠球菌临床分离株的分子相关性。本研究中使用的379株分离株均为1991年至1996年6年间从28家医院和3家长期护理机构收集的耐万古霉素屎肠球菌分离株。对于这379株分离株，有73种脉冲场凝胶电泳（PFGE）菌株类型。在菌株类型内，存在多达6个限制性片段差异。大多数分离株（70%）属于6种菌株类型，分别命名为M1（36%）、M2（3%）、M3（18%）、M4（6%）、M10（4%）和M11（3%）。PFGE菌株M1在1993年至1996年期间从13家医院的135名患者中培养得到。菌株类型M2在1991年至1992年期间从两家医院的11名患者中培养得到，1992年后未观察到。菌株类型M3在1994年至1996年期间从10家医院的70名患者中培养得到。M4和M10分别在1995年至1996年期间从3家医院的23名患者和两家医院的15名患者中培养得到。M11在1996年从4家医院的13名患者中培养得到。28家医院中有23家有某些分离株克隆传播的证据。对来自一家医院和两家附属长期护理机构的103株分离株进行的质粒含量和杂交分析表明，这些菌株含有1至8个质粒。交配实验表明，这些分离株中有94株的万古霉素耐药性以<10(-9)至10(-4)的转移频率转移到无质粒的屎肠球菌GE-1中。庆大霉素耐药性和红霉素耐药性以不同频率共转移。vanA基因探针与23株分离株的质粒以及72株分离株的染色体杂交。vanB基因探针与8株分离株的染色体杂交。本研究结果表明，在密歇根州东南部6年期间，耐万古霉素屎肠球菌菌株在医院间和医院内传播。大多数研究的分离株属于相同的少数PFGE菌株，表明克隆传播是耐药性传播的主要原因。
