Fridkin S K, Yokoe D S, Whitney C G, Onderdonk A, Hooper D C
Infectious Disease Division, Massachusetts General Hospital, Boston 02114-2696, USA.
J Clin Microbiol. 1998 Apr;36(4):965-70. doi: 10.1128/JCM.36.4.965-970.1998.
In 1996, the dominant (43%) strain of vancomycin-resistant enterococci (VRE; type A) at Massachusetts General Hospital was identified at Brigham and Women's Hospital (BWH). To characterize the epidemiology of infection with type A isolates of VRE at BWH, we collected demographic and clinical data for all patients from whom VRE were isolated from a clinical specimen through September 1996. The first clinical isolates from all BWH patients from whom VRE were isolated were typed by pulsed-field gel electrophoresis of SmaI digests of chromosomal DNA. Among patients hospitalized after the first patient at BWH infected with a type A isolate of VRE was identified, exposures were compared between patients who acquired type A isolates of VRE and those who acquired other types of VRE. Isolates from 99 patients identified to have acquired VRE were most commonly from blood (n = 27), urine (n = 19), or wounds (n = 19). Three months after the index patient arrived at BWH and at a time when > or =12 types of strains of VRE were present, type A isolates of VRE became dominant; 39 of 75 (52%) of the study cohort had acquired type A isolates of VRE. We found no association between the acquisition of type A isolates of VRE and transfer from another institution or temporal overlap by service, ward, or floor with patients known to have acquired type A isolates of VRE. By multivariate analysis, only residence in the medical intensive care unit (adjusted odds ratio [OR], 3.2; 95% confidence interval [CI], 1.4 to 107) and the receipt of two or more antibiotics per patient-day (adjusted OR, 12.2; 95% CI, 1.2 to 9.0) were associated with the acquisition of strain A. This strain of VRE, dominant at two Boston hospitals, was associated with intensity of antibiotic exposures (i.e., two or more antibiotics per patient-day). We hypothesize that this strain may have unidentified properties providing a mechanism favoring its spread and dominance over other extant isolates, and further studies are needed to define these properties.
1996年，马萨诸塞州总医院耐万古霉素肠球菌（VRE；A型）的优势菌株（占43%）在布莱根妇女医院（BWH）被鉴定出来。为了描述BWH医院A型VRE分离株感染的流行病学特征，我们收集了截至1996年9月所有从临床标本中分离出VRE的患者的人口统计学和临床数据。通过对染色体DNA的SmaI酶切产物进行脉冲场凝胶电泳，对所有BWH医院分离出VRE的患者的首批临床分离株进行分型。在BWH医院首例感染A型VRE分离株的患者之后住院的患者中，比较了获得A型VRE分离株的患者与获得其他类型VRE的患者之间的暴露情况。从99例被确定获得VRE的患者中分离出的菌株最常见于血液（n = 27）、尿液（n = 19）或伤口（n = 19）。在首例患者到达BWH医院三个月后，当时存在≥12种VRE菌株类型，A型VRE分离株成为优势菌株；研究队列中的75例患者中有39例（52%）获得了A型VRE分离株。我们发现获得A型VRE分离株与从另一家机构转入或在服务、病房或楼层与已知获得A型VRE分离株的患者存在时间重叠之间没有关联。通过多变量分析，只有入住医疗重症监护病房（调整后的优势比[OR]，3.2；95%置信区间[CI]，1.4至10.7）以及每位患者每天接受两种或更多种抗生素治疗（调整后的OR，12.2；95%CI，1.2至9.0）与获得A菌株有关。这种在两家波士顿医院占优势的VRE菌株与抗生素暴露强度（即每位患者每天两种或更多种抗生素）有关。我们推测这种菌株可能具有未被识别的特性，为其传播和在其他现存分离株中占据优势提供了一种机制，需要进一步研究来确定这些特性。
