Antibiotic susceptibility among aerobic gram-negative bacilli in intensive care units in 5 European countries. French and Portuguese ICU Study Groups

Abstract

Context: Surveillance of antibiotic resistance is especially important in intensive care units (ICUs) because the infection rates are much higher there than in other hospital wards and most epidemics with multiresistant bacteria originate in ICUs.

Objective: To evaluate the incidence of decreased antibiotic susceptibility among aerobic gram-negative bacilli isolated from patients in ICUs.

Design: Consecutive specimens collected on clinical indications from ICU patients were cultured and tested. Minimum inhibitory concentrations for amikacin, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, piperacillin, and piperacillin-tazobactam were determined using E test.

Setting: Eighteen hospitals in Belgium, 40 in France, 20 in Portugal, 30 in Spain, and 10 in Sweden.

Subjects: A total of 9166 gram-negative strains were initially isolated from 7308 patients between June 1994 and June 1995.

Main outcome measures: The incidence of decreased susceptibility, defined as the sum of resistant and intermediate categories with use of the minimum inhibitory concentration break points recommended by the National Committee for Clinical Laboratory Standards.

Results: The most frequently isolated organisms were Enterobacteriaceae (59%) followed by Pseudomonas aeruginosa (24%). The main sources were respiratory tract (42%), urine (26%), blood (14%), abdomen (11%), and skin and soft tissue (7%). Decreased antibiotic susceptibility across all species and drugs was highest in Portuguese ICUs followed by French, Spanish, Belgian, and Swedish ICUs. The highest incidence of resistance was seen in all countries among P aeruginosa (up to 37% resistant to ciprofloxacin in Portuguese ICUs and 46% resistant to gentamicin in French ICUs), Enterobacter species, Acinetobacter species, and Stenotrophomonas maltophilia, and in Portugal and France among Klebsiella species.

Conclusion: The high incidence of reduced antibiotic susceptibility among gram-negative bacteria in these ICUs suggests that more effective strategies are needed to control the selection and spread of resistant organisms.