title: First detection of OKP-A β-lactamase in two Serratia marcescens isolates in China.
abstract: Two strains of Enterobacteriaceae producing prodigiosin were isolated from meat in the Sichuan province of China in 2010. The strains were identified by Vitek system, 16S rDNA, rpoB, pfs and luxS genes. Minimum inhibitory concentrations were determined using the broth microdilution method. The two strains were screened for the presence of β-lactamase genes (blaTEM, blaSHV, blaOKP, and blaCTX-M genes). Based on PCR amplification and 16S rDNA sequencing the analysed strains were identified as Serratia marcescens. In addition, morphological and biochemical identification showed that the two stains were definitely S. marcesens. Antimicrobial susceptibility test showed that both strains were resistant to ampicillin and first-generation cephalosporins while being susceptible to cefotaxime, ceftiofur, ceftriaxone, imipenem and aztreonam. It was found that blaOKP had been identified first from the two S. marcescens strains, ch1 and ch2. The isolates were closely related as shown by pulsed-field gel electrophoresis (PFGE). The narrow-spectrum OKP-A β-lactamase gene blaOKP-A-13 was found to be chromosomally located in S. marcescens. The isolates produced a β-lactamase with a pI of approximately 8.2, which corresponds to the OKPA family. Findings indicate that OKP enzymes are not Klebsiella pneumoniae-specific chromosomal ?-lactamases, and the first isolation of S. marcescens producing OKP-A ?-lactamase suggests that the blaOKP gene may be disseminated between different species.
authors.affiliation: Laboratory of Microbiology, Sichuan Agricultural University, Dujiangyan, China. zoulkcn@hotmail.com
authors.forename: Likou
authors.initials: L
authors.lastname: Zou
authors.forename: Xin
authors.initials: X
authors.lastname: Pan
authors.forename: Qi
authors.initials: Q
authors.lastname: Wu
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.forename: Shuliang
authors.initials: S
authors.lastname: Liu
authors.forename: Cheng
authors.initials: C
authors.lastname: Lin
authors.forename: Bei
authors.initials: B
authors.lastname: Li
authors.forename: Xuxi
authors.initials: X
authors.lastname: Wang
authors.forename: Mei
authors.initials: M
authors.lastname: Long
authors.forename: Fang
authors.initials: F
authors.lastname: Guo
mesh_terms: D000668:Ampicillin Resistance / Q000235:genetics; D018550:Cephalosporin Resistance / Q000235:genetics; D002681:China; D005516:Food Microbiology; D006801:Humans; D008460:Meat / Q000382:microbiology*; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics*; D012706:Serratia marcescens / Q000145:classification / Q000187:drug effects / Q000235:genetics*; D013045:Species Specificity; D014170:Transformation, Genetic / Q000235:genetics; D018440:beta-Lactam Resistance / Q000235:genetics*; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D012336:RNA, Ribosomal, 16S; D001618:beta-Lactamases