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Infect Control Hosp Epidemiol. 2010 Nov;31(11):1148-53. doi: 10.1086/656590.

Acquisition of multidrug-resistant gram-negative bacteria: incidence and risk factors within a long-term care population.

Author information

1
Department of Medicine, Hebrew Senior Life, Boston, Massachusetts 02131, USA. erinofallon@hrca.harvard.edu

Erratum in

  • Infect Control Hosp Epidemiol. 2011 Jan;32(1):99. Kandell, Ruth [corrected to Kandel, Ruth].

Abstract

BACKGROUND AND OBJECTIVE:

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.

DESIGN:

Prospective cohort study.

SETTING:

Three separate wards at a 600-bed LTCF in metropolitan Boston, Massachusetts, during the period October 31, 2006, through October 22, 2007.

PARTICIPANTS:

One hundred seventy-two LTCF residents.

METHODS:

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.

RESULTS:

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).

CONCLUSIONS:

Acquisition of MDR gram-negative bacteria occurred frequently through resident-to-resident transmission. Existing infection control interventions need to be reevaluated.

PMID:
20923286
DOI:
10.1086/656590
[Indexed for MEDLINE]

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