In vitro susceptibilities of aerobic and facultatively anaerobic Gram-negative bacilli isolated from patients with intra-abdominal infections worldwide: 2004 results from SMART (Study for Monitoring Antimicrobial Resistance Trends)

Objectives: SMART (Study for Monitoring Antimicrobial Resistance Trends) is an ongoing study to monitor worldwide antimicrobial resistance trends among aerobic and facultatively anaerobic Gram-negative bacilli (GNB) isolated from intra-abdominal infections. This 2004 report summarizes the most recently completed annual data from SMART. Methods: During 2004, 81 medical centres from 28 countries in five global regions collected intra-abdominal GNB for antimicrobial susceptibility testing using broth microdilution according to the Clinical and Laboratory Standards Institute guidelines. Results: A total of 6156 unique aerobic and facultatively anaerobic GNB were isolated from intra-abdominal infections. Enterobacteriaceae composed 86% of the total isolates. Among the 12 antimicrobial agents tested, the carbapenems and amikacin were the most consistently active against the Enterobacteriaceae. Escherichia coli was the most commonly isolated species (48%), and the susceptibility rate to the quinolones was lowest in Asia/Pacific and Latin America. Extended-spectrum β-lactamases (ESBLs) were detected phenotypically in 10% of E. coli, 17% of Klebsiella spp. and 22% of Enterobacter spp. worldwide, representing a slight increase over the two previous years. ESBL producers typically had a more antibiotic-resistant profile than non-ESBL producers but were usually susceptible to the carbapenems. Conclusions: Antimicrobial resistance among GNB isolated from intra-abdominal infections continued to be a problem worldwide in 2004, with the highest rates of resistance overall in the Asia/Pacific region. The carbapenems and amikacin were the most consistently active agents in vitro against Enterobacteriaceae isolated from intra-abdominal infections worldwide.