Assessment of extended-spectrum β-lactamase, KPC carbapenemase and porin resistance mechanisms in clinical samples of Klebsiella pneumoniae and Enterobacter spp

Assessment of extended-spectrum β-lactamase, KPC carbapenemase and porin resistance mechanisms in clinical samples of Klebsiella pneumoniae and Enterobacter spp

Abstract The emergence and spread of resistance mechanisms in Gram-negative bacilli has complicated the treatment of serious nosocomial infections. Current automated systems for detection of Klebsiella pneumoniae carbapenemase (KPC)-producing isolates are unreliable. One possible straightforward alt...

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Bibliographic Details
Published in:International journal of antimicrobial agents Vol. 42; no. 1; pp. 76 - 79
Main Authors: Jaskulski, M.R, Medeiros, B.C, Borges, J.V, Zalewsky, R, Fonseca, M.E.C, Marinowic, D.R, Rocha, M.P, Nodari, P, Machado, D.C
Format: Journal Article
Language:English
Published: Netherlands Elsevier B.V 01-07-2013
Subjects:
Anti-Bacterial Agents - pharmacology
beta-Lactamases - genetics
beta-Lactams - pharmacology
Drug Resistance, Bacterial
Enterobacteriaceae - drug effects
Enterobacteriaceae - enzymology
Enterobacteriaceae - genetics
Enterobacteriaceae - isolation & purification
Enterobacteriaceae Infections - microbiology
Ertapenem
ESBL
Humans
Infectious Disease
KPC
Microbial Sensitivity Tests
OmpC
OmpF
Polymerase Chain Reaction
Porins - genetics
Resistance
Resistance
ESBL
OmpF
OmpC
Ertapenem
KPC
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Summary:Abstract The emergence and spread of resistance mechanisms in Gram-negative bacilli has complicated the treatment of serious nosocomial infections. Current automated systems for detection of Klebsiella pneumoniae carbapenemase (KPC)-producing isolates are unreliable. One possible straightforward alternative method is evaluation of ertapenem resistance. However, the accuracy of this method is affected by other resistance mechanisms such as AmpC gene expression or extended-spectrum β-lactamase production associated with porin loss. This study included 128 samples of K. pneumoniae and Enterobacter spp. that were non-susceptible to ertapenem. The disk diffusion and Etest method were applied to determine susceptibility to imipenem, meropenem and ertapenem. Isolates exhibiting intermediate or complete resistance to ertapenem were evaluated for resistance mechanisms. blaTEM , blaSHV , blaCTX-M , blaCTX-M-2 and blaKPC genes were tested for by PCR, and the presence of outer membrane protein was investigated by dot-blot assay. blaTEM was detected in 52.9% and 10.3%, blaSHV in 29.4% and 0.94%, blaCTX-M in 41.4% and 1.9% and blaCTX-M-2 in 23.5% and 1.9% of K. pneumoniae and Enterobacter cloacae isolates, respectively. The blaKPC gene was present in 12.6% of Enterobacter spp. isolates. OmpC and OmpF were present in 6.6% of E. cloacae isolates. These results indicate that several resistance mechanisms contribute to potential therapeutic failure of carbapenem therapy and point to the need for better detection methods and surveillance strategies.
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ISSN:0924-8579
1872-7913
DOI:10.1016/j.ijantimicag.2013.03.009