BACKGROUND Colonization pressure is a risk factor for intensive care unit (ICU)-acquired multi-drug-resistant organisms (MDROs). AIM To measure the long-term respective impact of colonization pressure on ICU-acquired extended-spectrum β-lactamase-producing Enterobacterales (ESBL-PE) and meticillin-resistant Staphylococcus aureus (MRSA). METHODS All patients admitted to two ICUs (medical and surgical) between January 1997 and December 2015 were included in this retrospective observational study. Rectal and nasal surveillance cultures were obtained at admission and weekly thereafter. Contact precautions were applied for colonized or infected patients. Colonization pressure was defined as the ratio of the number of MDRO-positive patient-days (PDs) of each MDRO to the total number of PDs. Single-level negative binomial regression models were used to evaluate the incidence of weekly MDRO acquisition. FINDINGS Among the 23,423 patients included, 2327 (10.0%) and 1422 (6.1%) were colonized with ESBL-PE and MRSA, respectively, including 660 (2.8%) and 351 (1.5%) acquisitions. ESBL-PE acquisition increased from 0.51/1000 patient-exposed days (PEDs) in 1997 to 6.06/1000 PEDs in 2015 (P<0.001). In contrast, MRSA acquisition decreased steadily from 3.75 to 0.08/1000 PEDs (P<0.001). Controlling for period-level covariates, colonization pressure in the previous week was associated with MDRO acquisition for ESBL-PE (P<0.001 and P=0.04 for medical and surgical ICU, respectively), but not for MRSA (P=0.34 and P=0.37 for medical and surgical ICU, respectively). The increase in colonization pressure was significant above 100/1000 PDs for ESBL-PE. CONCLUSION Colonization pressure contributed to the increasing incidence of ESBL-PE but not MRSA. This study suggests that preventive control measures should be customized to MDROs.

中文翻译：

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定居压力对两个重症监护病房中产生广谱β-内酰胺酶的肠杆菌和耐甲氧西林金黄色葡萄球菌的获取的影响：一项为期19年的回顾性监测。

背景技术定植压力是重症监护病房（ICU）获得的多重耐药生物（MDRO）的危险因素。目的测量长期定植压力对ICU获得的广谱β-内酰胺酶产肠杆菌（ESBL-PE）和耐甲氧西林金黄色葡萄球菌（MRSA）的长期影响。方法这项回顾性观察研究纳入了1997年1月至2015年12月期间接受两次ICU（医疗和外科）的所有患者。入院时及其后每周进行直肠和鼻腔监测培养。接触预防措施适用于定植或感染的患者。殖民压力定义为每个MDRO的MDRO阳性患者天数（PDs）与PD总数之比。单级负二项式回归模型用于评估每周MDRO采集的发生率。结果在23423例患者中，有2327例（10.0％）和1422例（6.1％）分别定植了ESBL-PE和MRSA，包括660例（2.8％）和351例（1.5％）。ESBL-PE获取量从1997年的0.51 / 1000患者暴露天数（PED）增加到2015年的6.06 / 1000 PEDs（P <0.001）。相比之下，MRSA采集从3.75稳定下降至0.08 / 1000 PED（P <0.001）。控制时期水平的协变量，ESBL-PE的前一周定植压力与MDRO采集相关（对于医疗和外科ICU，分别为P <0.001和P = 0.04），而对于MRSA，则不相关（P = 0.34和P =医疗和手术ICU分别为0.37）。对于ESBL-PE，定植压力的增加高于100/1000 PDs。结论定植压力导致ESBL-PE发病率增加，但未引起MRSA增加。这项研究表明，预防控制措施应针对MDRO进行定制。