To identify risk factors for the respiratory acquisition of extended-spectrum beta-lactamase (ESBL)-producing Klebsiella pneumoniae among patients admitted to a neurosurgical intensive care unit (NSICU) and to modify them without changing general infection control measures.

Nested case-control and intervention study.

A 1,200-bed, tertiary-care teaching hospital with a 17-bed NSICU.

Sputa of all patients admitted to the NSICU were cultured weekly during the study. From October 2002 through February 2003, 29 case-patients from whose sputum ESBL-producing K. pneumoniae was isolated were detected and 59 controls-patients were randomly selected among patients without any positive isolate of ESBL-producing K. pneumoniae. After analyzing the risk factors, we intervened to modify them and compared the acquisition rate of ESBL-producing K. pneumoniae before (October 2002 to February 2003) and after (April to August 2003) the intervention.

Multivariate analysis showed that prior exposure to third-generation cephalosporins (TGCs) (OR, 6.0; CI95, 1.9 to 18.6; P= .002) was an independent risk factor of ESBL-producing K. pneumoniae acquisition. The neurosurgical team was notified of the result, and the infectious diseases specialist visited the NSICU three times a week to regulate TGC use during the intervention period. Patients admitted before the intervention were older than patients admitted after. The respiratory acquisition of ESBL-producing K. pneumoniae per 1,000 patient-days (13.5 [CI95, 8.9 to 18.1] vs 2.7 [CI95, 0.9 to 4.6]) and the antimicrobial use density of TGCs (38.2 ± 5.0 vs 17.3 ± 2.6; P < .001) decreased significantly after the intervention.

Prior exposure to TGCs was an independent risk factor for the respiratory acquisition of ESBL-producing K. pneumoniae, and less use of TGCs was associated with a decrease in acquisition.