Characterization of Fosfomycin Resistant Extended-Spectrum β-Lactamase-Producing Escherichia coli Isolates from Human and Pig in Taiwan.
To investigate the efficacy of fosfomycin against extended-spectrum β-lactamases (ESBL) producing Escherichia coli in Taiwan and the resistance mechanisms and characterization of human and pig isolates, we analyzed 145 ESBL-producing isolates collected from two hospitals (n = 123) and five farms (n = 22) in Taiwan from February to May, 2013. Antimicrobial susceptibilities were determined. Clonal relatedness was determined by PFGE and multi-locus sequence typing. ESBLs, ampC, and fosfomycin resistant genes were detected by PCR, and their flanking regions were determined by PCR mapping and sequencing. The fosfomycin resistant mechanisms, including modification of the antibiotic target (MurA), functionless transporters (GlpT and UhpT) and their regulating genes such as uhpA, cyaA, and ptsI, and antibiotic inactivation by enzymes (FosA and FosC), were examined. The size and replicon type of plasmids carrying fosfomycin resistant genes were analyzed. Our results revealed the susceptibility rates of fosfomycin were 94% for human ESBL-producing E. coli isolates and 77% for pig isolates. The PFGE analysis revealed 79 pulsotypes. No pulsotype was found existing in both human and pig isolates. Three pulsotypes were distributed among isolates from two hospitals. ISEcp1 carrying blaCTX-M-group 9 was the predominant transposable elements of the ESBL genes. Among the thirteen fosfomycin resistant isolates, functionless transporters were identified in 9 isolates. Three isolates contained novel amino acid substitutions (Asn67Ile, Phe151Ser and Trp164Ser, Val146Ala and His159Tyr, respectively) in MurA (the target of fosfomycin). Four isolates had fosfomycin modified enzyme (fosA3) in their plasmids. The fosA3 gene was harboured in an IncN-type plasmid (101 kbp) in the three pig isolates and an IncB/O-type plasmid (113 kbp) in the human isolate. In conclusion, we identified that 6% and 23% of the ESBL-producing E. coli from human and pigs were resistant to fosfomycin, respectively, in Taiwan. No clonal spread was found between human and pig isolates. Functionless transporters were the major cause of fosfomycin resistance, and the fosA3-transferring plasmid between isolates warrants further monitoring.
Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC; Department of Marine Biotechnology and Resources, National Sun Yat-sen University, Kaohsiung, Taiwan, ROC.
Sung-Pin
SP
Tseng
Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
Sheng-Fan
SF
Wang
Division of Infectious Diseases, Kaohsiung Medical University Chung-Ho Memorial hospital, Kaohsiung, Taiwan, ROC; Department of Internal Medicine, Ministry of Health and Welfare Pingtung Hospital, Kaohsiung, Taiwan, ROC.
Cheng-Yu
CY
Kuo
Department of Medical Laboratory Science and Biotechnology, College of Health Sciences, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
Jun-Wei
JW
Huang
Department of Microbiology and Immunology, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC.
Wei-Chun
WC
Hung
Graduate Institute of Animal Vaccine Technology, National Pingtung University of Science and Technology, Neipu, Pingtung, Taiwan, ROC.
Guan-Ming
GM
Ke
Department of Laboratory Medicine, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan, ROC; College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan, ROC; Department of Internal Medicine, Kaohsiung Medical University Hospital, Taiwan, Kaohsiung, ROC.
Po-Liang
PL
Lu
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D004926:Escherichia coli / Q000187:drug effects* / Q000235:genetics*; D004927:Escherichia coli Infections / Q000188:drug therapy / Q000382:microbiology / Q000662:veterinary; D005578:Fosfomycin / Q000494:pharmacology*; D006801:Humans; D008826:Microbial Sensitivity Tests / Q000379:methods; D010957:Plasmids / Q000235:genetics; D013552:Swine; D013624:Taiwan; D001618:beta-Lactamases / Q000235:genetics*
D000900:Anti-Bacterial Agents; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D005578:Fosfomycin; D001618:beta-Lactamases