Phenotypic and  molecular characterization of CTX-M-14 extended-spectrum β-lactamase and  plasmid-mediated ACT-like AmpC β-lactamase produced by Klebsiella  pneumoniae isolates from chickens in Henan Province, China.
Extended-spectrum  β-lactamases  (ESBLs) and AmpC β-lactamases  produced by a clinical isolate of Klebsiella pneumoniae from chickens  were detected with confirmatory phenotypic tests of the Clinical and Laboratory  Standards Institute. The minimum inhibitory concentrations of 18 antibacterial  drugs against K. pneumoniae were determined by the 2-fold microdilution  method. The genotype and subtype of the ESBL-producing and AmpC β-lactamase-producing K. pneumoniae isolate were identified by PCR amplification of the  enzyme-encoding genes followed by DNA sequencing analysis. K. pneumoniae K(1) isolate  was an ESBL-producing and AmpC β-lactamase-producing  bacteria with high resistance to β-lactam antibiotics, such as penicillins,  third-generation cephalosporins, fluoroquinolones, and aminoglycosides. The  sequence analysis showed that K. pneumoniae K(1) harbored  TEM-type, SHV-type, CTX-M-type, and ACT-type AmpC β-lactamase  nucleotide sequences. The TEM-type sequence was designated as TEM-1; the  SHV-type sequence was designated as SHV-11; the CTX-M-type sequence was  designated as CTX-M-14. Compared with the ACT-like sequence (EF078894), the  ACT-type sequence was characterized by 8 nucleotide mutations (A(75)G, C(84)G, T(90)C, A(105)G, G(213)A, G(246)A, C(309)T,  and T(315)C). Only one mutation at position 75 led to an amino  acid substitution (Asn28Lys). The bla(ACT) type  was an ACT-like derivative.
Department of Pharmacology and Toxicology, College of Animal Husbandry and Veterinary Science, Henan Agricultural University, Zhengzhou, P.R. China.
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D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics*; D002645:Chickens / Q000382:microbiology*; D002681:China; D005798:Genes, Bacterial / Q000235:genetics; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids / Q000235:genetics*; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000096:biosynthesis / Q000235:genetics*
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; C456080:beta-lactamase CTX-M-14; C048795:AmpC beta-lactamases; D001618:beta-Lactamases