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Longitudinal survey of carbapenem resistance and resistance mechanisms in Enterobacteriaceae and non-fermenters from the USA in 2007–09

Longitudinal survey of carbapenem resistance and resistance mechanisms in Enterobacteriaceae and... BackgroundAntibiotic resistance is problematic in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and is often associated with serious infections. Carbapenems are often one of the few remaining therapeutic options, so it is important to monitor carbapenem activity against these pathogens and to identify resistance mechanisms.MethodsCarbapenem susceptibilities were determined for 14 359 Enterobacteriaceae, 3614 P. aeruginosa and 994 A. baumannii from the USA (2007–09). Klebsiella pneumoniae with doripenem MICs ≥2 mg/L (n = 88), and P. aeruginosa (n = 452), A. baumannii (n = 349) and other enterics (n = 13) with doripenem MICs ≥4 mg/L were screened for carbapenem resistance mechanisms.ResultsDoripenem/meropenem and imipenem susceptibilities for Enterobacteriaceae were >99% and 89%, respectively. Doripenem susceptibility (2007–09) for P. aeruginosa was 87.4%–84.1%; comparable to meropenem and higher than imipenem. For A. baumannii, doripenem susceptibility (2007–09) was 63%–58.2%; lower than imipenem and meropenem. Resistant K. pneumoniae had KPC and lacked porins OmpK35/OmpK36. In 2009, 3.4% of all K. pneumoniae possessed KPC. Five other enterics and one P. aeruginosa possessed KPC. Resistance mechanisms in P. aeruginosa were loss of porin OprD (90%), efflux (55%) and elevated AmpC activity (25%). Acquired carbapenemases OXA-23/-24 were present in 48% of resistant A. baumannii. VIM metallo-β-lactamases were present in three P. aeruginosa and one A. baumannii isolates.ConclusionsDoripenem and meropenem were more active than imipenem against Enterobacteriaceae and P. aeruginosa from the USA. Carbapenem resistance mechanisms included serine carbapenemases, elevated AmpC activity, efflux and porin deficiencies occurring mostly in P. aeruginosa. Metallo-β-lactamases were found in <0.1% of isolates. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Antimicrobial Chemotherapy Oxford University Press

Longitudinal survey of carbapenem resistance and resistance mechanisms in Enterobacteriaceae and non-fermenters from the USA in 2007–09

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References (56)

Publisher
Oxford University Press
Copyright
© The Author 2011. Published by Oxford University Press on behalf of the British Society for Antimicrobial Chemotherapy. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com
Subject
Original research
ISSN
0305-7453
eISSN
1460-2091
DOI
10.1093/jac/dkr290
pmid
21775338
Publisher site
See Article on Publisher Site

Abstract

BackgroundAntibiotic resistance is problematic in Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter baumannii, and is often associated with serious infections. Carbapenems are often one of the few remaining therapeutic options, so it is important to monitor carbapenem activity against these pathogens and to identify resistance mechanisms.MethodsCarbapenem susceptibilities were determined for 14 359 Enterobacteriaceae, 3614 P. aeruginosa and 994 A. baumannii from the USA (2007–09). Klebsiella pneumoniae with doripenem MICs ≥2 mg/L (n = 88), and P. aeruginosa (n = 452), A. baumannii (n = 349) and other enterics (n = 13) with doripenem MICs ≥4 mg/L were screened for carbapenem resistance mechanisms.ResultsDoripenem/meropenem and imipenem susceptibilities for Enterobacteriaceae were >99% and 89%, respectively. Doripenem susceptibility (2007–09) for P. aeruginosa was 87.4%–84.1%; comparable to meropenem and higher than imipenem. For A. baumannii, doripenem susceptibility (2007–09) was 63%–58.2%; lower than imipenem and meropenem. Resistant K. pneumoniae had KPC and lacked porins OmpK35/OmpK36. In 2009, 3.4% of all K. pneumoniae possessed KPC. Five other enterics and one P. aeruginosa possessed KPC. Resistance mechanisms in P. aeruginosa were loss of porin OprD (90%), efflux (55%) and elevated AmpC activity (25%). Acquired carbapenemases OXA-23/-24 were present in 48% of resistant A. baumannii. VIM metallo-β-lactamases were present in three P. aeruginosa and one A. baumannii isolates.ConclusionsDoripenem and meropenem were more active than imipenem against Enterobacteriaceae and P. aeruginosa from the USA. Carbapenem resistance mechanisms included serine carbapenemases, elevated AmpC activity, efflux and porin deficiencies occurring mostly in P. aeruginosa. Metallo-β-lactamases were found in <0.1% of isolates.

Journal

Journal of Antimicrobial ChemotherapyOxford University Press

Published: Oct 20, 2011

Keywords: doripenem Klebsiella pneumoniae Pseudomonas aeruginosa Acinetobacter baumannii surveillance

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