Garrett D O, Jochimsen E, Murfitt K, Hill B, McAllister S, Nelson P, Spera R V, Sall R K, Tenover F C, Johnston J, Zimmer B, Jarvis W R
Hospital Infections Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.
Infect Control Hosp Epidemiol. 1999 Mar;20(3):167-70. doi: 10.1086/501605.
Coagulase-negative staphylococci (CNS) are the major cause of nosocomial bloodstream infection. Emergence of vancomycin resistance among CNS is a serious public health concern, because CNS usually are multidrug-resistant, and glycopeptide antibiotics, among which only vancomycin is available in the United States, are the only remaining effective therapy. In this report, we describe the first bloodstream infection in the United States associated with a Staphylococcus epidermidis strain with decreased susceptibility to vancomycin.
We reviewed the hospital's microbiology records for all CNS strains, reviewed the patient's medical and laboratory records, and obtained all available CNS isolates with decreased susceptibility to vancomycin. Blood cultures were processed and CNS isolates identified by using standard methods; antimicrobial susceptibility was determined by using minimum inhibitory concentration (MIC) and disk-diffusion methods. Nares cultures were obtained from exposed healthcare workers (HCWs) to identify possible colonization by CNS with decreased susceptibility to vancomycin.
The bloodstream infection by an S. epidermidis strain with decreased susceptibility to vancomycin occurred in a 49-year-old woman with carcinoma. She had two blood cultures positive for CNS; both isolates were S. epidermidis. Although susceptible to vancomycin by the disk-diffusion method (16-17 mm), the isolates were intermediate by MIC (8-6 microg/mL). The patient had received an extended course of vancomycin therapy; she died of her underlying disease. No HCW was colonized by CNS with decreased susceptibility to vancomycin.
This is the first report in the United States of bloodstream infection due to S. epidermidis with decreased susceptibility to vancomycin. Contact precautions likely played a role in preventing nosocomial transmission of this strain, and disk-diffusion methods may be inadequate to detect CNS with decreased susceptibility to vancomycin.
凝固酶阴性葡萄球菌（CNS）是医院血流感染的主要原因。CNS中出现万古霉素耐药性是一个严重的公共卫生问题，因为CNS通常对多种药物耐药，而糖肽类抗生素（在美国仅有万古霉素）是唯一 remaining 有效的治疗方法。在本报告中，我们描述了美国首例与对万古霉素敏感性降低的表皮葡萄球菌菌株相关的血流感染。
我们查阅了医院所有CNS菌株的微生物学记录，查阅了患者的医疗和实验室记录，并获取了所有对万古霉素敏感性降低的可用CNS分离株。采用标准方法处理血培养物并鉴定CNS分离株；通过最低抑菌浓度（MIC）和纸片扩散法测定抗菌药物敏感性。从接触过的医护人员（HCW）中获取鼻腔培养物，以确定是否存在对万古霉素敏感性降低的CNS定植。
一名49岁的癌症女性发生了由对万古霉素敏感性降低的表皮葡萄球菌菌株引起的血流感染。她的两次血培养CNS呈阳性；两个分离株均为表皮葡萄球菌。尽管通过纸片扩散法对万古霉素敏感（16 - 17毫米），但分离株通过MIC测定为中介（8 - 6微克/毫升）。该患者接受了延长疗程的万古霉素治疗；她死于基础疾病。没有HCW被对万古霉素敏感性降低的CNS定植。
这是美国首例关于对万古霉素敏感性降低的表皮葡萄球菌引起血流感染的报告。接触预防措施可能在预防该菌株的医院传播中发挥了作用，并且纸片扩散法可能不足以检测对万古霉素敏感性降低的CNS。
