Merrer J, Santoli F, Appéré de Vecchi C, Tran B, De Jonghe B, Outin H
Service de Réanimation Médicale, Centre Hospitalier de Poissy, St Germain, France.
Infect Control Hosp Epidemiol. 2000 Nov;21(11):718-23. doi: 10.1086/501721.
To determine the roles of "colonization pressure," work load or patient severity in patient acquisition of methicillin-resistant Staphylococcus aureus (MRSA) in intensive care units (ICUs).
Prospectively collected data from October 1996 through December 1998.
A 12-bed medical ICU in a university-affiliated general hospital.
Patients with risk factors for MRSA admitted to the ICU were screened within 72 hours of admission and weekly thereafter. MRSA was considered imported if detected during the first 72 hours of admission and nosocomial if detected only thereafter. Three screening strategies were used on admission during three consecutive periods.
The unit of time chosen for measurements was the week. Weekly colonization pressure (WCP) was defined as the number of MRSA-carrier patient-days/total number of patient-days. Patient severity (number of deaths, Simplified Acute Physiologic Score [SAPS] II), work load (number of admis sions, Omega score), and colonization pressure (number of MRSA carriers at the time of admission, WCP) were compared with the number of MRSA-nosocomial cases during the following week.
Of the 1,016 patients admitted over 116 weeks, 691 (68%) were screened. MRSA was imported in 91 (8.9%) admitted patients (13.1% of screened patients) and nosocomial in 46 (4.5%). The number of MRSA-nosocomial cases was correlated to the SAPS II (P=.007), the Omega 3 score (P=.007), the number of MRSA-imported cases (P=.01), WCP (P<.0001), and the screening period (P<.0001). In multivariate analysis, WCP was the only independent predictive factor for MRSA acquisition (P=.0002). Above 30% of WCP, the risk of acquisition of MRSA was approximately fivefold times higher (relative risk, 4.9; 95% confidence interval, 1.2-19.9; P<.0001).
Acquisition of MRSA in ICU patients is strongly and independently influenced by colonization pressure.
确定“定植压力”、工作量或患者病情严重程度在重症监护病房（ICU）患者获得耐甲氧西林金黄色葡萄球菌（MRSA）过程中的作用。
前瞻性收集1996年10月至1998年12月的数据。
一所大学附属医院的拥有12张床位的内科ICU。
入住ICU且有MRSA危险因素的患者在入院72小时内及之后每周进行筛查。如果在入院的前72小时内检测到MRSA，则认为是输入性的；如果仅在此之后检测到，则认为是医院内感染。在连续三个时期的入院时采用了三种筛查策略。
选择的测量时间单位是周。每周定植压力（WCP）定义为MRSA携带者患者天数/患者总天数。将患者病情严重程度（死亡人数、简化急性生理学评分[SAPS]II）、工作量（入院人数、欧米伽评分）和定植压力（入院时MRSA携带者人数、WCP）与接下来一周的医院内MRSA病例数进行比较。
在116周内入院的1016例患者中，691例（68%）接受了筛查。91例（8.9%）入院患者（占筛查患者的13.1%）的MRSA是输入性的，46例（4.5%）是医院内感染的。医院内MRSA病例数与SAPS II（P = 0.007）、欧米伽3评分（P = 0.007）、输入性MRSA病例数（P = 0.01）、WCP（P < 0.0001）和筛查时期（P < 0.0001）相关。在多变量分析中，WCP是MRSA获得的唯一独立预测因素（P = 0.0002）。当WCP高于30%时，获得MRSA的风险大约高出五倍（相对风险，4.9；95%置信区间，1.2 - 19.9；P < 0.0001）。
ICU患者获得MRSA受到定植压力的强烈且独立影响。
