Na'was T, Hawwari A, Hendrix E, Hebden J, Edelman R, Martin M, Campbell W, Naso R, Schwalbe R, Fattom A I
W. W. Karakawa Microbial Pathogenesis Laboratory, NABI, Rockville, Maryland 20852, USA.
J Clin Microbiol. 1998 Feb;36(2):414-20. doi: 10.1128/JCM.36.2.414-420.1998.
Staphylococcus aureus is a major cause of nosocomial infections. During the period from March 1992 to March 1994, the patients admitted to the intensive care unit of the University of Maryland Shock Trauma Center were monitored for the development of S. aureus infections. Among the 776 patients eligible for the study, 60 (7.7%) patients developed 65 incidents of nosocomial S. aureus infections. Of the clinical isolates, 43.1% possessed a polysaccharide type 5 capsule, 44.6% possessed a type 8 capsule, and the remaining 12.3% had capsules that were not typed by the type 5 or type 8 antibodies. Six antibiogram types were noted among the infection-related isolates, with the majority of the types being resistant only to penicillin and ampicillin. It was noted that the majority of cases of pneumonia were caused by relatively susceptible strains, while resistant strains were isolated from patients with bacteremia and other infections. Only 16 (6.3%) of the isolates were found to be methicillin-resistant S. aureus (MRSA). DNA fingerprinting by pulsed-field gel electrophoresis showed 36 different patterns, with characteristic patterns being found for MRSA strains and the strains with different capsular types. Clonal relationships were established, and the origins of the infection-related isolates in each patient were determined. We conclude that (i) nosocomial infection-related isolates from the shock trauma patients did not belong to a single clone, although the predominance of a methicillin-resistant genotype was noted, (ii) most infection-related S. aureus isolates were relatively susceptible to antibiotics, but a MRSA strain was endemic, and (iii) for practical purposes, the combination of the results of capsular and antibiogram typing can be used as a useful epidemiological marker.
金黄色葡萄球菌是医院感染的主要原因。在1992年3月至1994年3月期间，对马里兰大学休克创伤中心重症监护病房收治的患者进行了金黄色葡萄球菌感染发生情况的监测。在776名符合研究条件的患者中，有60名（7.7%）患者发生了65起医院内金黄色葡萄球菌感染事件。在临床分离株中，43.1%具有5型多糖荚膜，44.6%具有8型荚膜，其余12.3%的荚膜不能用5型或8型抗体分型。在与感染相关的分离株中发现了六种抗菌谱类型，大多数类型仅对青霉素和氨苄西林耐药。值得注意的是，大多数肺炎病例是由相对敏感的菌株引起的，而耐药菌株则从菌血症和其他感染患者中分离得到。仅16株（6.3%）分离株被发现为耐甲氧西林金黄色葡萄球菌（MRSA）。脉冲场凝胶电泳DNA指纹图谱显示有36种不同模式，MRSA菌株和不同荚膜类型的菌株具有特征性模式。建立了克隆关系，并确定了每位患者感染相关分离株的来源。我们得出以下结论：（i）尽管注意到耐甲氧西林基因型占优势，但休克创伤患者医院感染相关分离株并不属于单一克隆；（ii）大多数与感染相关的金黄色葡萄球菌分离株对抗生素相对敏感，但有一种MRSA菌株呈地方性流行；（iii）实际上，荚膜分型和抗菌谱分型结果的结合可作为一种有用的流行病学标志物。
