There are limited long-term data on the trends in incidence and characteristics of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia (MRSAB) in intensive care units (ICUs) in which infection control measures have been adopted. We evaluated the trend of incidence and changes in characteristics of MRSA bacteremia in ICUs at a tertiary-care hospital over 10 years using prospective cohort data. ICU-acquired bacteremia was defined as S. aureus bacteremia (SAB) that occurred 48 h or more after ICU admission. MRSA isolates were collected and subjected to microbiological and genotypic analyses. A total of 529 SAB episodes were identified among 367,175 ICU patients. Of these episodes, 288 (54.4%) were ICU acquired, 238 (82.6%) of which were MRSAB. The incidence density of ICU-acquired MRSAB decreased from 1.32 per 1,000 patient-days to 0.19 per 1,000 patient-days (a decrease of 20% annually; P < 0.001 for trend), whereas that of non-ICU-acquired MRSAB fluctuated and did not decrease significantly. The decline in ICU-acquired MRSAB was due to lower catheter-related infection and less pneumonia. Rates of persistent bacteremia and 12-week mortality also fell significantly. A total of 183 isolates were collected from 238 ICU-acquired MRSAB cases. There were no significant changes in the geometric means of vancomycin MICs, vancomycin heteroresistance, or the sequence types of MRSA isolates over time. Chlorhexidine MICs decreased (P < 0.001 for trend) in association with a decline in frequency of the qacA or qacB gene that was related to reductions in specific spa types. The incidence of MRSAB in ICUs has decreased dramatically over time, but most of the microbiological and genotypic characteristics of MRSA isolates have not changed.

中文翻译：

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重症监护病房耐甲氧西林金黄色葡萄球菌细菌血症的发病率降低：三级医院的10年临床，微生物学和基因型分析。

在采取感染控制措施的重症监护病房（ICU）中，耐甲氧西林金黄色葡萄球菌（MRSAB）菌血症（MRSAB）的发病率和特征的趋势的长期数据有限。我们使用前瞻性队列数据评估了三级医院10年间ICU中MRSA菌血症发生率和特征变化的趋势。ICU获得性菌血症定义为金黄色葡萄球菌ICU入院后48小时或更长时间发生的菌血症（SAB）。收集MRSA分离物，并进行微生物学和基因型分析。在367,175名ICU患者中共鉴定出529次SAB发作。在这些发作中，有288例（54.4％）是获得ICU，其中238例（82.6％）是MRSAB。ICU采集的MRSAB的发生密度从每1000个患者日1.32个下降到每1000个患者日0.19个（每年下降20％；P <趋势为0.001），而非ICU获得的MRSAB则波动并且没有明显下降。ICU获得性MRSAB的下降是由于与导管相关的感染减少和肺炎减少。持续菌血症的发生率和12周死亡率也显着下降。从238例ICU获得的MRSAB病例中总共收集了183株。随着时间的流逝，万古霉素MIC的几何平均值，万古霉素异抗性或MRSA分离物的序列类型没有显着变化。洗必泰MICs降低（趋势P < 0.001）与qacA或qacB基因频率的下降有关，这与特定spa的减少有关类型。随着时间的流逝，ICU中MRSAB的发生率显着下降，但是MRSA分离物的大多数微生物学和基因型特征并未改变。