AmpC β-lactamases in nosocomial isolates of Klebsiella pneumoniae from India.

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dc.contributor.authorGupta, Varsha
dc.contributor.authorKumarasamy, Karthikeyan
dc.contributor.authorGulati, Neelam
dc.contributor.authorGarg, Ritu
dc.contributor.authorKrishnan, Padma
dc.contributor.authorChander, Jagdish
dc.date.accessioned2013-01-24T10:10:31Z
dc.date.available2013-01-24T10:10:31Z
dc.date.issued2012-08
dc.description.abstractBackground & objectives: AmpC β-lactamases are clinically significant since these confer resistance to cephalosporins in the oxyimino group, 7-α methoxycephalosporins and are not affected by available β-lactamase inhibitors. In this study we looked for both extended spectrum β-lactamases (ESBL) and AmpC β-lactamases in Klebsiella pneumoniae clinical isolates. Methods: One hundred consecutive, non-duplicate clinical isolates of K. pneumoniae collected over a period of one year (June 2008 - June 2009) were included in the study. An antibiotic susceptibility method was used with 10 antibiotics for Gram-negative infections which helped in screening for ESBL and AmpC β-lactamases and also in confirmation of ESBL production. The detection of AmpC β-lactamases was done based on screening and confirmatory tests. For screening, disc diffusion zones of cefoxitin <18 mm was taken as cefoxitin resistant. All cefoxitin resistant isolates were tested further by AmpC disk test and modified three dimensional test. Multiplex-PCR was performed for screening the presence of plasmid-mediated AmpC genes. Results: Of the 100 isolates of K. pneumoniae studied, 48 were resistant to cefoxitin on screening. AmpC disk test was positive in 32 (32%) isolates. This was also confirmed with modified three dimensional test. Indentation indicating strong AmpC producer was observed in 25 isolates whereas little distortion (weak AmpC) was observed in 7 isolates. ESBL detection was confirmed by a modification of double disk synergy test in 56 isolates. Cefepime was the best cephalosporin in synergy with tazobactam for detecting ESBL production in isolates co-producing AmpC β-lactamases. The subsets of isolates phenotypically AmpC β-lactamase positive were subjected to amplification of six different families of AmpC gene using multiplex PCR. The sequence analysis revealed 12 CMY-2 and eight DHA-1 types. Interpretation & conclusions: Tazobactam was the best β-lactamase inhibitor for detecting ESBL in presence of AmpC β-lactamase as this is a very poor inducer of AmpC gene. Amongst cephalosporins, cefepime was the best cephalosporin in detecting ESBL in presence of AmpC β-lactamase as it is least hydrolyzed by AmpC enzymes. Cefepime-tazobactam combination disk test would be a simple and best method in detection of ESBLs in Enterobacteriaceae co-producing AmpC β-lactamase in the routine diagnostic microbiology laboratories.en_US
dc.identifier.citationGupta Varsha, Kumarasamy Karthikeyan, Gulati Neelam, Garg Ritu, Krishnan Padma, Chander Jagdish. AmpC β-lactamases in nosocomial isolates of Klebsiella pneumoniae from India. Indian Journal of Medical Research. 2012 Aug; 136(2): 237-241.en_US
dc.identifier.urihttps://imsear.searo.who.int/handle/123456789/144675
dc.language.isoenen_US
dc.source.urihttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC3461735/en_US
dc.subjectAmpC enzymeen_US
dc.subjectβ-lactamasesen_US
dc.subjectESBLen_US
dc.subjectKlebsiella pneumoniaeen_US
dc.subjectplasmid mediateden_US
dc.subjectresistanceen_US
dc.subject.meshBacterial Proteins --isolation & purification
dc.subject.meshCefoxitin
dc.subject.meshDrug Resistance, Bacterial
dc.subject.meshKlebsiella pneumoniae --isolation & purification
dc.subject.meshHumans
dc.subject.meshIndia
dc.subject.meshPenicillanic Acid --analogs & derivatives
dc.subject.meshbeta-Lactamases --isolation & purification
dc.titleAmpC β-lactamases in nosocomial isolates of Klebsiella pneumoniae from India.en_US
dc.typeArticleen_US
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