[Genotype distribution of extended-spectrum beta-lactamases and AmpC beta-lactamases produced in Escherichia coli isolated from men with urinary infection].
OBJECTIVE
To study the genotype distribution of extended-spectrum p-lactamases (ESBLs) and AmpC p-lactamases produced in E. coli isolated from men with urinary infection in Nanjing.


METHODS
Organisms of clinical infection were identified by automatic microbial system (Vitek-32). ESBLs were detected by disk diffusion confirmatory test, and ESBLs and AmpC p-lactamases by three-dimensional extract test (TDET) , the presence of plasmid-mediated ESBLs and ampC genes determined by PCR, and conjugal transfer assays of the ampC resistance determinants carried out by a broth mating procedure.


RESULTS
ESBLs were produced in 24. 6% (46/187) of the E. coli and the 46 E. coli isolates showed p-lactamase activity in TDET, 3 positive for both ESBLs and AmpC beta-lactamases and 43 for ESBLs only. Forty-four of the 46 isolates were shown by PCR to contain at least one of the genes blaTEM, blaOXA, bla(CTX-M), but no blaSHA. AmpC specific amplication products were observed in 3 of the 46 isolates, of which 2 were of CIT type, and 1 of DHA type. All of the 3 transconjugants transferred the plasmids harbouring ampC genes to recipients.


CONCLUSIONS
CTX-M is the most common genotype in plasmid-mediated ESBLs produced by E. coli isolated from men with urinary infection in Nanjing. Present findings indicate that AmpC-producing E. coli are present in this hospital, and ampC-encoding plasmids are transferable.
Wang
Wei-ping
WP
PLA Institute of Medical Laboratory Science, Nanjing General Hospital of Nanjing Command, Nanjing, Jiangsu 210002, China. njzywwp@sohu.com
Shao
Hai-feng
HF
Wang
Jin-na
JN
Zhang
Xiao-wei
XW
Shi
Li-ning
LN
D001426:Bacterial Proteins / Q000032:analysis / Q000235:genetics*; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000145:classification* / Q000201:enzymology / Q000235:genetics; D005838:Genotype; D006801:Humans; D008297:Male; D010957:Plasmids / Q000235:genetics; D016133:Polymerase Chain Reaction; D014552:Urinary Tract Infections / Q000382:microbiology*; D001618:beta-Lactamases / Q000032:analysis / Q000235:genetics*
D001426:Bacterial Proteins; C048795:AmpC beta-lactamases; D001618:beta-Lactamases