Prevalence and quinolone resistance of fecal carriage of extended-spectrum β-lactamase-producing Escherichia coli in 6 communities and 2 physical examination center populations in Shanghai, China.
OBJECTIVE
To characterize extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolates from the community, determine their antibiotic sensitivity profiles and quinolone resistance mechanisms, and identify any horizontal transfer of ESBL genes.


METHODS
One thousand seven hundred thirty-two stool samples were collected from healthy individuals in 6 communities and 2 physical examination centers in Shanghai, China. ESBL-producing E. coli was screened and confirmed by confirmatory test and E. coli-identifying agars. PCR was used to amplify ESBL-encoding genes blaCTX-M, blaTEM, blaSHVgenes, and quinolone resistance-relating genes gyrA, gryB, parC, parE, qnrS, aac (6')-Ib-cr, oqxA, and oqxB, followed by sequencing. Antimicrobial susceptibility tests and conjugation assays were also performed.


RESULTS
Overall, 528 isolates were identified as ESBL-producing E. coli, and all were positive for blaCTX-M. CTX-M-14 was found most frequently (48.9%). S83L±D87N in gyrA and S80I in parC were the most common topoisomerase mutations. Plasmid-mediated quinolone resistance (PMQR) determinants were also detected, including qnrS1 (11.7%), qnrS2 (3.7%), aac (6')-Ib-cr(12.8%), oqxA(8.5%), and oqxB(11.0%). The rate of multidrug resistance was very high (92.2%). ESBL genes transferred successfully in 39.4% isolates.


CONCLUSIONS
There is a high prevalence of fecal carriage of ESBL-producing E. coli in the community in Shanghai, with high-level quinolone resistance and CTX-M-14 being the predominant CTX-M enzyme.
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Qi
Q
Ni
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Yuan
Y
Tian
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Lihua
L
Zhang
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Cen
C
Jiang
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Danfeng
D
Dong
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China.
Zhen
Z
Li
Department of Emergency Intensive Care Unit, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No. 197 Ruijin ER Road, Shanghai 200025, China. Electronic address: maoeq@yeah.net.
Enqiang
E
Mao
Department of Laboratory Medicine, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, No.197 Ruijin ER Road, Shanghai 200025, China. Electronic address: pyb9861@sina.com.
Yibing
Y
Peng
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology; D002681:China / Q000453:epidemiology; D017714:Community-Acquired Infections / Q000453:epidemiology* / Q000382:microbiology; D024881:Drug Resistance, Bacterial; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000302:isolation & purification; D004927:Escherichia coli Infections / Q000453:epidemiology* / Q000382:microbiology; D005243:Feces / Q000382:microbiology; D005260:Female; D022761:Gene Transfer, Horizontal; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D010957:Plasmids / Q000032:analysis; D016133:Polymerase Chain Reaction; D015995:Prevalence; D015363:Quinolones / Q000494:pharmacology*; D017422:Sequence Analysis, DNA; D055815:Young Adult; D001618:beta-Lactamases / Q000378:metabolism*
D000900:Anti-Bacterial Agents; D015363:Quinolones; D001618:beta-Lactamases
CTX-M, quinolone resistance; Community; Escherichia coli; Extended-spectrum β-lactamase