title: Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli Strains Isolated from Retail Foods in Shaanxi Province, China.
abstract: Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli strains have been reported worldwide; however, the incidence and characterization of foodborne ESBL-producing E. coli strains have been rarely reported in the People's Republic of China. Among a collection of 659 E. coli isolates recovered from retail foods in Shaanxi Province, People's Republic of China, 223 cefoxitin-resistant and/or cefoperazone-resistant isolates were screened for ESBL production with the double disk diffusion test. The ESBL-producing isolates were characterized for antimicrobial resistance and the presence of blaTEM, blaSHV, and blaCTX-M genes. Isolates with blaCTX-M were further classified by PCR as having blaCTX-M-1, blaCTX-M-2, blaCTX-M-8, blaCTX-M-9, or blaCTX-M-25. One hundred forty-seven isolates were identified as ESBL positive. PCR detection revealed that 146 isolates (99.3%) contained the blaCTX-M gene. Among these isolates, 42 (28.8%) were positive for the enzyme CTX-M-1, 5 (3.4%) for CTX-M-2, and 99 (67.8%) for CTX-M-9. No CTX-M-8 and CTX-M-25 were found in this study. One hundred fifteen isolates (78.2%) were positive for the blaTEM gene, but blaSHV was not detected. Among the 147 ESBL-producing E. coli isolates, 75 (51.0%), 35 (23.8%), and 4 (2.7%) isolates were positive for blaTEM and blaCTX-M-9, blaTEM and blaCTX-M-1, and blaTEM and blaCTX-M-2, respectively. All of the 147 ESBL-producing isolates were resistant to three or more non-β-lactam antibiotics. This study provides evidence that foodborne E. coli can harbor ESBL-encoding genes. Thus, food could be a vehicle for the dissemination of ESBL-producing E. coli strains, a situation that requires surveillance and appropriate management strategies.
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China.
authors.forename: Meili
authors.initials: M
authors.lastname: Xi
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Wu
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China.
authors.forename: Xin
authors.initials: X
authors.lastname: Wang
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China.
authors.forename: Baowei
authors.initials: B
authors.lastname: Yang
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China. foodscixiaodong@yahoo.com.
authors.forename: Xiaodong
authors.initials: X
authors.lastname: Xia
authors.affiliation: College of Food Science and Engineering, Northwest Agriculture-Forest University, Shaanxi 72100, People's Republic of China.
authors.forename: Dongyu
authors.initials: D
authors.lastname: Li
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents / Q000494:pharmacology; D001426:Bacterial Proteins / Q000235:genetics; D002511:Cephalosporins / Q000494:pharmacology; D002645:Chickens; D002681:China; D024901:Drug Resistance, Multiple, Bacterial; D004926:Escherichia coli / Q000145:classification / Q000201:enzymology / Q000302:isolation & purification*; D005506:Food Contamination / Q000032:analysis*; D005516:Food Microbiology; D008460:Meat / Q000382:microbiology; D016133:Polymerase Chain Reaction; D001618:beta-Lactamases / Q000235:genetics
chemical_list: D000890:Anti-Infective Agents; D001426:Bacterial Proteins; D002511:Cephalosporins; C071167:beta-lactamase CTX-2; C055184:beta-lactamase TEM-3; D001618:beta-Lactamases