Research Papers:

Characteristics and genetic diversity of multi-drug resistant extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolated from bovine mastitis

Tariq Ali, Sadeeq ur Rahman, Limei Zhang, Muhammad Shahid, Dandan Han, Jian Gao, Shiyao Zhang, Pamela L. Ruegg, Umer Saddique and Bo Han _

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Oncotarget. 2017; 8:90144-90163. https://doi.org/10.18632/oncotarget.21496

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Tariq Ali1,*, Sadeeq ur Rahman2,*, Limei Zhang1, Muhammad Shahid1, Dandan Han1, Jian Gao1, Shiyao Zhang1, Pamela L. Ruegg3, Umer Saddique4 and Bo Han1

1Department of Clinical Veterinary Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, P.R. China

2College of Veterinary Sciences and Animal Husbandry, Abdul Wali Khan University, Garden Campus, Mardan, Pakistan

3Department of Dairy Science, University of Wisconsin, Madison, WI, USA

4Department of Animal Health, The University of Agriculture, Peshawar, Pakistan

*These authors have contributed equally and co-first authors

Correspondence to:

Bo Han, email: [email protected]

Keywords: E. coli, ESBL, multilocus sequence typing, PCR-based replicon typing, split network analysis

Received: June 15, 2017     Accepted: August 23, 2017     Published: October 04, 2017


A characterization of the drug resistance profiles, identification of PCR-based replicon typing, and multilocus sequence typing (MLST) and analysis of 46 ESBL-producing Escherichia coli from cows with mastitis are described. All multidrug-resistant isolates of various phylogenetic groups (A = 31, B1= 3, B2 = 2, D = 10) were ESBL-producers of genotypes CTX-M-15 (29), CTX-M-55 (4), CTX-M-14 (4), CTX-M-3 (1), CTX-M-1 (1), TEM (22) and SHV (8) that were found on conjugative plasmids of diverse incompatibility groups (primarily IncF). Transconjugation experiments indicated successful (100%) trans-conjugation, which was verified phenotypically and genotypically. A total of 28 sequence types (ST) were identified, with 10% of isolates being ST410, and 9 other ST that were assigned arbitrary numbers, reflecting the degree of diversity. Multilocus sequence analysis revealed two lineages, a dominant and a small lineage. Split-decomposition showed intraspecies recombination clearly contributed in genetic recombination generating genotypic diversity among the isolates, and a lack of interspecies recombination. This coherent analysis on genetic structure of multidrug-resistant pathogenic E. coli population isolated from mastitic-milk weaponized with resistance elements from a large, rapidly developing country will be a helpful contribution for epidemiology and surveillance of drug resistance patterns, and understanding their global diversity.

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