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290 Risk of acquiring Extended-spectrum-Beta-lactamase (ESBL) producing Klebsiella pneumoniae and Escherichia coli from prior room occupants in the intensive care unit

Saturday, April 2, 2011
Trinity Ballroom (Hilton Anatole)
Adebola Ajao, MPH , University of Maryland, Baltimore, MD
J. Kristie Johnson, PhD , University of Maryland, Baltimore, MD
Anthony D. Harris, MD, MS , University of Maryland, Baltimore, MD
Min Zhan, PhD , University of Maryland, Baltimore, MD
Jessina C. McGregor, PhD , Oregon State University College of Pharmacy, Portland, OR
Kerri A. Thom, MD, MS , University of Maryland, Baltimore, MD
Jon P. Furuno, PhD , University of Maryland, Baltimore, MD
Background: Environmental contamination by patients colonized with extended-spectrum-β-lactamase (ESBL)-producing Klebsiella pneumoniae and Escherichia coli has been reported; however, no study has assessed the association between environmental contamination and acquisition of ESBL-K. pneumoniae and E. coli in non-outbreak settings.

Objective: To determine if admission to a room previously occupied by a patient colonized with ESBL-producing bacteria increased the risk of acquiring ESBL-K. pneumoniae or E. coli colonization among intensive care unit (ICU) patients.

Methods: A retrospective cohort study was conducted among patients admitted to the University of Maryland Medical Center (UMMC) medical ICU (MICU) and surgical ICU (SICU) between September 1, 2001 and January 31, 2006. Peri-rectal surveillance cultures were collected from all patients on ICU admission, weekly and at ICU discharge. Inclusion criteria were ICU length of stay >24 hours and having an ESBL-negative peri-rectal culture on ICU admission. Patients were classified as “exposed” if the immediate prior occupant of the room to which they were admitted had a peri-rectal culture positive for ESBL-K. pneumoniae or E. coli. The outcome of interest was a peri-rectal culture positive for ESBL-K. pneumoniae or E. coli during the ICU stay. Multivariable logistic regression was used to model the association between prior room occupants’ ESBL status and acquisition of ESBL-K. pneumoniae or E. coli by the subsequent room occupant.

Results: There were 6,404 patients admitted to the MICU and SICU during the study period of which 180 (3%) had surveillance cultures positive for ESBL-K. pneumoniae or E.coli on ICU admission and were excluded. Of the remaining patients, 4,535 (71%) stayed in the ICU for >24 hours and were thereby at-risk for acquiring ESBL colonization. Fifty-nine (1%) of the at-risk patients acquired ESBL-K. pneumoniae or E. coli during their ICU stay. Variables associated with ESBL-K. pneumoniae or E. coli acquisition were prior room occupant’s positive ESBL status (adjusted odds ratio (AOR)= 2.17, 95% confidence interval (CI)= 0.85–5.56), admission to the MICU versus the SICU (AOR= 2.65, 95% CI= 1.55–4.55), receipt of anti-anaerobic antibiotics prior to ICU admission (AOR= 2.12, 95% CI= 1.26–3.55), and ICU time-at-risk (AOR= 1.04, 95% CI= 1.03–1.06).

Conclusions: Patients whose prior room occupant was colonized with ESBL- K. pneumoniae or E. coli were at increased risk of acquiring ESBL-K. pneumoniae or E. coli after adjusting for potential confounding variables; however this association was not statistically significant. Further study is needed to quantify the role of the environment and the importance of adequate terminal cleaning on acquisition of these antibiotic-resistant bacteria.