Journal Article

CTX-M-15 extended-spectrum β-lactamase from Nigerian <i>Klebsiella pneumoniae</i>

Olusegun O. Soge, Anne Marie Queenan, Kayode K. Ojo, Bolanle A. Adeniyi and Marilyn C. Roberts

in Journal of Antimicrobial Chemotherapy

Published on behalf of British Society for Antimicrobial Chemotherapy

Volume 57, issue 1, pages 24-30
Published in print January 2006 | ISSN: 0305-7453
Published online November 2005 | e-ISSN: 1460-2091 | DOI:
CTX-M-15 extended-spectrum β-lactamase from Nigerian Klebsiella pneumoniae

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Objectives: In this study, extended-spectrum β-lactamases (ESBLs) were characterized from 30 selected multidrug-resistant Klebsiella pneumoniae strains isolated from patients with community-acquired urinary tract infections from Southwest Nigeria.

Methods: The β-lactamases were phenotypically characterized using isoelectric focusing, genotypically characterized using PCR assays and hybridization of the PCR products. Two of the blaCTX-M genes were completely sequenced. The location of the CTX-M-type genes was determined using transformation, DNA–DNA hybridization, PCR assays and hybridization of the PCR products from the Escherichia coli transformants.

Results: All 30 isolates produced at least one β-lactamase. Seventeen of the isolates were resistant to cefotaxime, and had ≥100-fold reduction in susceptibility with cefotaxime plus clavulanic acid (4 mg/L), indicating the presence of an ESBL. The 17 isolates were shown to have blaCTX-M genes that were associated with large plasmids (≥58 kb), which also carried a tetracycline resistance gene, tet(A), and various aminoglycoside resistance genes. Two CTX-M-type genes were sequenced and had amino acid sequences indistinguishable from previously sequenced CTX-M-15 β-lactamases. The ISEcp1 element was located upstream of blaCTX-M-15 in the same position as previously described. In addition, 23 of the isolates produced TEM β-lactamases, 27 produced SHV β-lactamases and four produced AmpC β-lactamases.

Conclusions: Thirty K. pneumoniae produced multiple β-lactamases, with 57% producing CTX-M enzymes. This is the first characterization of CTX-M-15-positive K. pneumoniae in Western Africa.

Keywords: K. pneumoniae; ESBLs; CTX-M enzymes

Journal Article.  3581 words.  Illustrated.

Subjects: Medical Oncology ; Critical Care

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