Contamination of Hospital Environment with ESBL-E is Inversely Associated with Carbapenem Exposure

The role of the hospital environment in transmission of ESBL-Klebsiella pneumoniae (ESBL-KP) and ESBL-Escherichia coli (ESBL-EC) is poorly defined. Recent data however suggest that in the hospital setting, ESBL-KP is more transmissible than ESBL-EC. Freeman, et al. (2014) sought therefore to measure the difference in hospital contamination rates between the two species and to identify key risk factors for contamination of the hospital environment with these organisms.

The researchers systematically sampled eight surfaces in the rooms and bathrooms of adult patients colonized or infected with ESBL-EC or ESBL-KP throughout their hospital stay. Data were collected on factors potentially affecting contamination rates. Environmental contamination was defined as recovery of an ESBL-producing organism matching the source patient's isolate. Multivariate logistic regression analysis was performed at the level of the patient visit using generalized estimating equations to identify independent predictors of environmental contamination.

The researchers found that 24 patients (11 with ESBL-KP, 11 ESBL-EC and two with both organisms) had 1104 swabs collected during 138 visits. The overall contamination rate was 3.4% (38/1104) and was significantly higher for ESBL-KP than ESBL-EC (5.4% versus 0.4%; p < 0.0001). After multivariate analysis, environmental contamination was found to be negatively associated with carbapenem exposure (OR 0.06 [95% CI 0.01-0.61]; p = 0.017) and positively associated with the presence of an indwelling urinary catheter (OR 6.12 [95% CI 1.23-30.37]; p = 0.027) and ESBL-KP in the source patient (OR 26.23 [95% CI 2.70-254.67]; p = 0.005).

The researchers conclude that contamination of the hospital environment with ESBL-E is inversely associated with carbapenem exposure. Predictors of hospital contamination with ESBL-E include: indwelling urinary catheters and ESBL-KP. Rooms of patients with ESBL-KP have substantially higher contamination rates than those with ESBL-EC. This finding may help explain the apparently higher transmissibility of ESBL-KP in the hospital setting. Their research was published in Antimicrobial Resistance and Infection Control.

Reference: Freeman JT, Nimmo J, Gregory E, Tiong A, De Almeida M, McAuliffe GN and Roberts SA. Predictors of hospital surface contamination with Extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae: patient and organism factors. Antimicrobial Resistance and Infection Control 2014, 3:5  doi:10.1186/2047-2994-3-5.