CTX-M-15 extended-spectrum (beta)-lactamase from Nigerian Klebsiella pneumoniae.
OBJECTIVE
In this study, extended-spectrum beta-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 beta-lactamases were phenotypically characterized using isoelectric focusing, genotypically characterized using PCR assays and hybridization of the PCR products. Two of the bla(CTX-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 beta-lactamase. Seventeen of the isolates were resistant to cefotaxime, and had > or =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 bla(CTX-M) genes that were associated with large plasmids (> or =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 beta-lactamases. The ISEcp1 element was located upstream of bla(CTX-M-15) in the same position as previously described. In addition, 23 of the isolates produced TEM beta-lactamases, 27 produced SHV beta-lactamases and four produced AmpC beta-lactamases.


CONCLUSIONS
Thirty K. pneumoniae produced multiple beta-lactamases, with 57% producing CTX-M enzymes. This is the first characterization of CTX-M-15-positive K. pneumoniae in Western Africa.
Soge
Olusegun O
OO
Department of Pharmaceutical Microbiology, University of Ibadan, Ibadan, Nigeria.
Queenan
Anne Marie
AM
Ojo
Kayode K
KK
Adeniyi
Bolanle A
BA
Roberts
Marilyn C
MC
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001483:Base Sequence; D017714:Community-Acquired Infections / Q000453:epidemiology / Q000382:microbiology*; D004269:DNA, Bacterial / Q000235:genetics; D024901:Drug Resistance, Multiple, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D005798:Genes, Bacterial; D006801:Humans; D017403:In Situ Hybridization; D007525:Isoelectric Focusing; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D009549:Nigeria / Q000453:epidemiology; D010957:Plasmids; D014552:Urinary Tract Infections / Q000453:epidemiology / Q000382:microbiology*; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; C473109:beta-lactamase CTX-M-15; D001618:beta-Lactamases