Frequency of occurrence and antimicrobial susceptibility of Gram-negative bacteremia isolates in patients with urinary tract infection: results from United States and European hospitals (2009–2011)

Abstract

We evaluated the frequency of occurrence and antimicrobial susceptibility patterns of Gram-negative bacteria isolated from bacteremic patients with UTI from European (EU) and United States (USA) hospitals during a 3-year period (2009–2011). Susceptibility testing was performed by the reference broth microdilution method on 2071 Gram-negative bacilli. The most frequently isolated pathogens were Escherichia coli (63·3/71·3% in USA/EU), Klebsiella spp. (16·7/11·2%) and Proteus mirabilis (6·4/5·0%). Escherichia coli susceptibility rates were generally similar in the USA and EU, with extended-spectrum beta-lactamase (ESBL)-phenotype rates at 8·1% in both regions. Among Klebsiella spp., ESBL rates varied from 11·4/17·1% in 2009 to 16·1/40·4% in 2011 in USA/EU, and susceptibility rates were generally lower in EU compared to the USA. Pseudomonas aeruginosa exhibited lower susceptibility rates to ceftazidime, meropenem and piperacillin/tazobactam in EU (78·4, 78·4 and 76·5%, respectively) compared to USA (91·2, 88·2 and 91·2%, respectively). In summary, very few antimicrobials provided satisfactory coverage (>90%) when tested against Klebsiella spp. and P. aeruginosa isolates in EU.

Keywords:

• Antimicrobial resistance
• ESBL
• Escherichia coli
• Klebsiella spp

Acknowledgments

We wish to express our appreciation to S. Benning and M. Stilwell in the preparation of this manuscript and to the JMI staff members for scientific assistance in performing this study.