Department of Medicine, Hebrew Senior Life, Boston, Massachusetts 02131, USA.
Infect Control Hosp Epidemiol. 2010 Nov;31(11):1148-53. doi: 10.1086/656590.
An improved understanding of the transmission dynamics of multidrug-resistant (MDR) gram-negative bacteria and the mechanism of acquisition in long-term care facilities (LTCFs) could aid in the development of prevention strategies specific to LTCFs. We thus investigated the incidence of acquisition of these pathogens among an LTCF population.
Prospective cohort study.
Three separate wards at a 600-bed LTCF in metropolitan Boston, Massachusetts, during the period October 31, 2006, through October 22, 2007.
One hundred seventy-two LTCF residents.
A series of rectal samples were cultured to determine acquisition of MDR gram-negative bacteria, defined as absence of MDR gram-negative bacterial colonization at baseline and de novo recovery of MDR gram-negative bacteria from a follow-up culture. Molecular typing was performed to identify genetically linked strains. A nested matched case-control study was performed to identify risk factors associated with acquisition.
Among 135 residents for whom at least 1 follow-up culture was performed, 52 (39%) acquired at least 1 MDR gram-negative organism during the study period. Thirty-two residents (62%) had not been colonized at baseline and had acquired at least 1 MDR gram-negative species at follow-up culture, and 20 residents (38%) were colonized at baseline and had acquired at least 1 MDR gram-negative species at follow-up culture. The most common coresistance pattern was resistance to extended-spectrum penicillins, ciprofloxacin, and gentamicin (57 isolates [42.5%]). Genetically related strains of MDR gram-negative bacteria were identified among multiple residents and between roommates. On conditional logistic regression analysis, antibiotic exposure during the study period was significantly associated with acquisition of MDR gram-negative bacteria (odds ratio, 5.6 [95% confidence interval, 1.1-28.7]; P = .04).
Acquisition of MDR gram-negative bacteria occurred frequently through resident-to-resident transmission. Existing infection control interventions need to be reevaluated.
深入了解多重耐药（MDR）革兰氏阴性菌的传播动态和在长期护理机构（LTCF）中的获得机制，有助于制定针对 LTCF 的特定预防策略。因此，我们调查了这些病原体在 LTCF 人群中的获得情况。
前瞻性队列研究。
马萨诸塞州波士顿市一家拥有 600 张床位的 LTCF 的三个独立病房，时间为 2006 年 10 月 31 日至 2007 年 10 月 22 日。
172 名 LTCF 居民。
对一系列直肠样本进行培养，以确定 MDR 革兰氏阴性菌的获得情况，定义为基线时无 MDR 革兰氏阴性菌定植，且随访培养中首次恢复 MDR 革兰氏阴性菌。进行分子分型以鉴定遗传相关菌株。进行巢式匹配病例对照研究，以确定与获得相关的危险因素。
在至少进行了 1 次随访培养的 135 名居民中，有 52 名（39%）在研究期间至少获得了 1 种 MDR 革兰氏阴性菌。32 名居民（62%）基线时未定植，且在随访培养中至少获得了 1 种 MDR 革兰氏阴性菌，20 名居民（38%）基线时定植，且在随访培养中至少获得了 1 种 MDR 革兰氏阴性菌。最常见的耐药模式是对广谱青霉素、环丙沙星和庆大霉素耐药（57 株[42.5%]）。MDR 革兰氏阴性菌的遗传相关菌株在多个居民和室友之间被鉴定出来。在条件逻辑回归分析中，研究期间的抗生素暴露与 MDR 革兰氏阴性菌的获得显著相关（比值比，5.6[95%置信区间，1.1-28.7]；P=0.04）。
MDR 革兰氏阴性菌的获得主要通过居民之间的传播。需要重新评估现有的感染控制干预措施。
