Seybold Ulrich, Kourbatova Ekaterina V, Johnson James G, Halvosa Sue J, Wang Yun F, King Mark D, Ray Susan M, Blumberg Henry M
Division of Infectious Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, GA 30303, USA.
Clin Infect Dis. 2006 Mar 1;42(5):647-56. doi: 10.1086/499815. Epub 2006 Jan 25.
Whether community-associated methicillin-resistant Staphylococcus aureus (MRSA) genotypes (e.g., USA300) are a major cause of bloodstream infections (BSIs) and health care-associated infections has been poorly defined.
Consecutive MRSA isolates recovered from patients with BSIs were prospectively collected at an urban public hospital. Molecular typing studies were performed. Prevalence and risk factors for the MRSA USA300 genotype were assessed.
One hundred thirty-two cases of MRSA BSI were documented over 7.5 months in 2004 (incidence, 6.79 per 1000 admissions); 116 isolates were available for genotyping. Characteristics of the 116 evaluable cases included: a mean age 47 years; 62% were male, 82% were African American, and 22% were HIV seropositive. The crude in-hospital mortality rate was 22%. In 107 cases (92%), there was contact with a health care facility within the year prior to infection, and a nosocomial infection (defined as positive blood culture results obtained >48 h after admission) occurred in 49 cases (42%). PFGE demonstrated that 39 (34%) of the 116 isolates were the MRSA USA300 genotype; 34 (29%) were USA100; 42 (36%) were USA500; and 1 (1%) was USA800. MRSA USA300 accounted for 28% of health care-associated BSIs and 20% of nosocomial MRSA BSIs. In multivariate analysis, isolation of the USA300 genotype was associated with injectiondrug use (OR, 3.67; 95% CI, 1.10-12.28) and skin and soft tissue infection (OR, 4.26; 95% CI, 1.08-16.84). Patients who resided in long-term care facilities (OR, 0.09; 95% CI, 0.01-0.82) and those who were treated with antimicrobials in the prior year were less likely to have MRSA USA300 genotype recovered (OR, 0.10; 95% CI, 0.02-0.49).
MRSA USA300 genotype, the predominant cause of community-associated MRSA infections in our area (Atlanta, GA), has now emerged as a significant cause of health care-associated and nosocomial BSI. MRSA USA300 as a nosocomial pathogen presents new challenges to infection control programs.
社区获得性耐甲氧西林金黄色葡萄球菌（MRSA）基因型（如USA300）是否为血流感染（BSIs）及医疗保健相关感染的主要病因，目前尚无明确定义。
在一家城市公立医院前瞻性收集从BSIs患者中分离出的连续MRSA菌株。进行分子分型研究。评估MRSA USA300基因型的患病率及危险因素。
2004年7.5个月期间记录了132例MRSA BSI（发病率为每1000例入院患者中6.79例）；116株菌株可用于基因分型。116例可评估病例的特征包括：平均年龄47岁；62%为男性，82%为非裔美国人，22%为HIV血清学阳性。院内粗死亡率为22%。107例（92%）患者在感染前一年与医疗机构有接触，49例（42%）发生了医院感染（定义为入院后>48小时血培养结果为阳性）。脉冲场凝胶电泳（PFGE）显示，116株菌株中有39株（34%）为MRSA USA300基因型；34株（29%）为USA100；42株（36%）为USA500；1株（1%）为USA800。MRSA USA300占医疗保健相关BSIs的28%，占医院获得性MRSA BSIs的20%。多因素分析显示，USA300基因型的分离与注射吸毒（比值比[OR]，3.67；95%置信区间[CI]，1.10 - 12.28）及皮肤和软组织感染（OR，4.26；95% CI，1.08 - 16.84）相关。居住在长期护理机构的患者（OR，0.09；95% CI，0.01 - 0.82）及前一年接受过抗菌药物治疗的患者，其MRSA USA300基因型被分离出的可能性较小（OR，0.10；95% CI，0.02 - 0.49）。
MRSA USA300基因型是我们所在地区（佐治亚州亚特兰大）社区获得性MRSA感染的主要病因，现已成为医疗保健相关及医院获得性BSI的重要病因。MRSA USA300作为医院病原体给感染控制计划带来了新挑战。
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