title: Prevalence of plasmid-mediated AmpC beta-lactamases in a Chinese university hospital from 2003 to 2005: first report of CMY-2-Type AmpC beta-lactamase resistance in China.
abstract: The aim of this study was to investigate the prevalences of plasmid-mediated AmpC beta-lactamases (PABLs) in isolates of Escherichia coli and Klebsiella spp. from a university hospital in China. A total of 1,935 consecutive nonrepeat clinical isolates of Escherichia coli, Klebsiella pneumoniae, and Klebsiella oxytoca were collected between January 2003 and July 2005. The isolates with cefoxitin zone diameters less than 18 mm (screen positive) were selected for PCR of the bla(AmpC) genes and sequencing. Fifty-four (2.79%) isolates harbored PABLs, as demonstrated by PCR and isoelectric focusing. Sequence analysis revealed the presence of bla(DHA-1) and bla(CMY-2) genes. The Southern blot hybridization studies confirmed that bla(CMY-2) and bla(DHA-1) were located on plasmids. Based on species, PABLs were detected in 4.29% (29 isolates of DHA-1 and 1 isolate of CMY-2) of K. pneumoniae, 1.91% (11 isolates of DHA-1 and 12 isolates of CMY-2) of E. coli, and 3.03% (1 isolate of DHA-1) of K. oxytoca isolates. In contrast to our anticipation, the occurrence rate of DHA-1-producing K. pneumonia significantly decreased (P < 0.01), from 7.54% in 2003 to 2.72% in 2004. The results of random amplified polymorphic DNA analysis indicate that the prevalences of DHA-1-producing K. pneumoniae and CMY-2-producing E. coli strains were not due to epidemic strains. In conclusion, DHA-1 was the most prevalent acquired AmpC beta-lactamase in this collection of isolates from a medical center in China, and DHA-1-producing K. pneumoniae was the most prevalent bacterium harboring a PABL. To the best of our knowledge, this is the first report of CMY-2-type AmpC beta-lactamases in the Chinese mainland.
authors.affiliation: Department of Clinical Laboratory Medicine, Sixth Affiliate Hospital of Shanghai Jiao Tong University, 600 Yi Shan Rd., Shanghai 200233, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Li
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.forename: Yuzhen
authors.initials: Y
authors.lastname: Du
authors.forename: Xiaofei
authors.initials: X
authors.lastname: Jiang
authors.forename: Jin
authors.initials: J
authors.lastname: Tang
authors.forename: Jianqiang
authors.initials: J
authors.lastname: Wang
authors.forename: Guilan
authors.initials: G
authors.lastname: Li
authors.forename: Yanqun
authors.initials: Y
authors.lastname: Jiang
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics*; D002510:Cephalosporinase / Q000235:genetics / Q000378:metabolism; D002681:China / Q000453:epidemiology; D004926:Escherichia coli / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D006785:Hospitals, University / Q000706:statistics & numerical data*; D007525:Isoelectric Focusing; D007710:Klebsiella Infections / Q000453:epidemiology / Q000382:microbiology; D041121:Klebsiella oxytoca / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D007711:Klebsiella pneumoniae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence; D017422:Sequence Analysis, DNA; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D002510:Cephalosporinase; C508952:DHA-1 cephalosporinase, E coli; C103022:beta-lactamase CMY-2; C048795:AmpC beta-lactamases; D001618:beta-Lactamases