Antibiotic resistance among gram-negative bacilli in US intensive care units: implications for fluoroquinolone use

Abstract

Context: Previous surveillance studies have documented increasing rates of antimicrobial resistance in US intensive care units (ICUs) in the early 1990s.

Objectives: To assess national rates of antimicrobial resistance among gram-negative aerobic isolates recovered from ICU patients and to compare these rates to antimicrobial use.

Design and setting: Participating institutions, representing a total of 43 US states plus the District of Columbia, provided antibiotic susceptibility results for 35 790 nonduplicate gram-negative aerobic isolates recovered from ICU patients between 1994 and 2000.

Main outcome measures: Each institution tested approximately 100 consecutive gram-negative aerobic isolates recovered from ICU patients. Organisms were identified to the species level. Susceptibility tests were performed, and national fluoroquinolone consumption data were obtained.

Results: The activity of most antimicrobial agents against gram-negative aerobic isolates showed an absolute decrease of 6% or less over the study period. The overall susceptibility to ciprofloxacin decreased steadily from 86% in 1994 to 76% in 2000 and was significantly associated with increased national use of fluoroquinolones.

Conclusions: This study documents the increasing incidence of ciprofloxacin resistance among gram-negative bacilli that has occurred coincident with increased use of fluoroquinolones. More judicious use of fluoroquinolones will be necessary to limit this downward trend.