Resistance of strains producing extended-spectrum beta-lactamases and genotype distribution in China.
OBJECTIVE
To investigate the resistance of Escherichia coli and Klebsiella pneumoniae producing extended-spectrum beta-lactamases (ESBLs) and the genotyping of ESBLs in China.


METHODS
MICs of 12 antibiotics against 50 strains (by random selection) of ESBLs-producing E. coli and K. pneumoniae were determined by E-test. The genotypes of ESBLs were analyzed by PCR, DNA sequencing and isoelectric focusing.


RESULTS
The susceptibility rate of 50 isolates was 100% in imipenem, 60%-80% in cefoperazone/sulbactam, ceftazidime and piperacillin/tazobactam, and lower in other antimicrobial agents tested. Only 6.0% of the isolates were sensitive to cefotaxime. Four hundred and forty-seven of 509 isolates had been confirmed the genotype of ESBLs. Four hundred and sixteen strains produced only one type of ESBLs, including CTX-M-14 (271 strains), CTX-M-3 (70 strains), CTX-M-24 (35 strains), CTX-M-22 (8 strains), CTX-M-15 (4 strains), CTX-M-9 (4 strains), CTX-M-28 (3 strains), CTX-M-12 (1 strain), CTX-M-13 (1 strain), CTX-M-27 (1 strain), CTX-M-29 (1 strain), SHV-12 (10 strains), SHV-5 (4 strains), SHV-2 (2 strains), and SHV-9 (1 strain). Thirty isolates carried two or three types of ESBLs, and producing CTX-M-14 and CTX-M-3 together were the most common type.


CONCLUSIONS
The resistance of E. coli and K. pneumonia producing ESBLs in China was a serious issue and CTX-M type ESBLs were the most common genotype. CTX-M-14 was the predominant genotype. Some isolates produced two or three ESBLs.
Department of Infectious Diseases, First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou 310003, China. yvys119@163.com
Yunsong
Y
Yu
Shujuan
S
Ji
Yagang
Y
Chen
Weilin
W
Zhou
Zeqing
Z
Wei
Lanjuan
L
Li
Yilin
Y
Ma
D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D002681:China; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000382:microbiology; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D005838:Genotype; D006801:Humans; D007525:Isoelectric Focusing; D007710:Klebsiella Infections / Q000382:microbiology; D007711:Klebsiella pneumoniae / Q000187:drug effects* / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D001618:beta-Lactamases / Q000096:biosynthesis* / Q000145:classification / Q000235:genetics / Q000302:isolation & purification
D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D029968:Escherichia coli Proteins; D001618:beta-Lactamases