Impact of empiric antibiotic use on development of infections caused by extended-spectrum beta-lactamase bacteria in a neonatal intensive care unit

Abstract

Background: The neonatal intensive care unit at Miller Children's Hospital changed from empiric use of cefotaxime and vancomycin (CEF) to tobramycin and vancomycin (TOB) for hospital-acquired infections in November 1999 because of an increase in infections caused by extended-spectrum beta-lactamase (ESBL)-producing bacteria. The objectives of this study were to evaluate the incidence and impact of this change on the development of ESBL infections.

Methods: We retrospectively reviewed medical records of infants who received CEF or TOB between January 1998 and December 2002. A standardized form was used to collect demographic data, information on antibiotic use, and culture results.

Results: The mean gestational age and birth weight of the 250 infants were 28.8 +/- 4.0 weeks and 1213.1 +/- 662 g, respectively. There were no differences between infants who received CEF (N = 130) or TOB (N = 120) in terms of gestational age, birth weight, device use, invasive procedures, or prior antibiotic use. There were 11 ESBL infections. Infants in the CEF group were more likely than those in the TOB group to develop ESBL infection (7.8% versus 0.8%, P = 0.008). There were 11 deaths, with none attributed to ESBL infection. In a multivariate analysis, duration of prior ampicillin and gentamicin use and exposure to CEF were associated with ESBL infection [odds ratio (OR): 3.1, 95% confidence interval (CI): 1.28-7.49, P = 0.012; and OR: 33.7; 95% CI: 1.02-1136, P = 0.05, respectively].

Conclusions: The change from empiric use of CEF to TOB was associated with a significant decrease in the incidence of ESBL infections.