Stampone Lucia, Del Grosso Maria, Boccia Delia, Pantosti Annalisa
Dipartimento di Malattie Infettive, Parassitarie ed Immunomediate, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
J Clin Microbiol. 2005 Apr;43(4):1575-80. doi: 10.1128/JCM.43.4.1575-1580.2005.
Recent data indicated that the rate of vancomycin resistance in bloodstream-infecting enterococcal isolates in Italy is one of the highest in Europe. The aims of this study were to characterize bloodstream-infecting vancomycin-resistant enterococci (VRE) obtained from various Italian hospitals and to establish whether the isolates were clonally related. During the years 2001 to 2003, a total of 39 VRE isolates were obtained from 19 hospital laboratories in various areas of Italy. Species identification and resistance genotypes of the isolates were obtained by multiplex PCR. Further characterization included antibiotic susceptibility testing, pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, detection of virulence genes (esp and hyl), and multilocus sequence typing (MLST) of selected isolates. VRE were identified as 31 Enterococcus faecium (VREfm) isolates and 8 E. faecalis isolates. All but one isolate carried the vanA gene; one VREfm isolate carried the vanB gene. Analysis of the PFGE profiles showed that 28 VREfm isolates shared a similar electrophoretic profile, designed type 1, and were clonally related. All type 1 isolates were resistant to ampicillin, streptomycin, gentamicin, and rifampin and were positive for the esp gene. MLST identified an allelic profile (ST78) comprising purK allele 1, belonging to the C1 clonal lineage, characteristic of human infection and hospital outbreak isolates. The vanB-carrying VREfm isolate, of PFGE type 2, was shown to be a single-locus variant of ST78. Our data indicate that the recent increase in the number of bloodstream infections caused by VRE in Italy is due to the spread of a hospital-adapted, multidrug-resistant VREfm clone belonging to an internationally disseminated lineage.
近期数据表明，意大利血流感染肠球菌分离株中万古霉素耐药率在欧洲位居前列。本研究旨在对从意大利各医院分离出的血流感染万古霉素耐药肠球菌（VRE）进行特征分析，并确定这些分离株是否存在克隆相关性。在2001年至2003年期间，共从意大利不同地区的19家医院实验室获得了39株VRE分离株。通过多重PCR对分离株进行菌种鉴定和耐药基因型分析。进一步的特征分析包括药敏试验、经SmaI酶切的基因组DNA脉冲场凝胶电泳（PFGE）、毒力基因（esp和hyl）检测以及对选定分离株的多位点序列分型（MLST）。VRE被鉴定为31株粪肠球菌（VREfm）分离株和8株屎肠球菌分离株。除1株分离株外，其余均携带vanA基因；1株VREfm分离株携带vanB基因。PFGE图谱分析显示，28株VREfm分离株具有相似的电泳图谱，被定义为1型，且存在克隆相关性。所有1型分离株对氨苄西林、链霉素、庆大霉素和利福平耐药，且esp基因呈阳性。MLST鉴定出一个等位基因谱（ST78），包含purK等位基因1，属于C1克隆谱系，是人类感染和医院暴发分离株的特征。携带vanB基因的VREfm分离株，PFGE为2型，是ST78的单一位点变体。我们的数据表明，意大利近期由VRE引起的血流感染数量增加是由于一种适应医院环境、多重耐药的VREfm克隆的传播，该克隆属于一个国际传播的谱系。
