CMY-2, CMY-8b, and DHA-1 plasmid-mediated AmpC β-lactamases among clinical isolates of Escherichia coli and Klebsiella pneumoniae from a university hospital, Thailand.
Between February 2005 and January 2006 in Srinagarind Hospital, Thailand, 44 from 1730 isolates (2.5%) of Escherichia coli and 8 from 982 isolates (0.8%) of Klebsiella pneumoniae were found to produce plasmid-mediated AmpC β-lactamases (pAmpCs) as detected by a cefoxitin-Hodge test followed by a multiplex polymerase chain reaction (PCR) technique. Fifteen of the 52 pAmpC-producing isolates also produced extended-spectrum β-lactamases. The ampC genes found in both organisms were bla(CMY-2) (46 isolates), bla(CMY-8b) (4 isolates), and bla(DHA-1) (2 isolates). These genes were present on plasmids. Twenty-five of the 46 CMY-2-producing isolates could transfer cefoxitin resistance to E. coli UB1637 by conjugation. More than 90% of the pAmpC-producing isolates were resistant to cefoxitin, but 80% to 90% of them were susceptible or intermediately susceptible to ceftazidime or cefotaxime. Enterobacterial repetitive intergenic consensus PCR analysis revealed that most isolates were of different strains, indicating the ease of transmission of these resistance determinants. This is the first report of CMY-2, CMY-8b, and DHA-1 β-lactamases in Thai isolates.
Singtohin
Supoj
S
Graduate School, Khon Kaen University, Khon Kaen, Thailand.
Chanawong
Aroonwadee
A
Lulitanond
Aroonlug
A
Sribenjalux
Pipat
P
Auncharoen
Amorn
A
Kaewkes
Wanlop
W
Songsri
Jirarat
J
Pienthaweechai
Keskaew
K
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000382:microbiology*; D006785:Hospitals, University; D006801:Humans; D007710:Klebsiella Infections / Q000382:microbiology*; D007711:Klebsiella pneumoniae / Q000201:enzymology* / Q000235:genetics / Q000302:isolation & purification; D008826:Microbial Sensitivity Tests / Q000379:methods; D010957:Plasmids; D016133:Polymerase Chain Reaction / Q000379:methods; D013785:Thailand; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000096:biosynthesis*; D047090:beta-Lactams / Q000494:pharmacology
D000900:Anti-Bacterial Agents; D004269:DNA, Bacterial; D047090:beta-Lactams; D001618:beta-Lactamases