Prevalence of qnrS-positive Escherichia coli from chicken in Thailand and possible co-selection of isolates with plasmids carrying qnrS and trimethoprim-resistance genes under farm use of trimethoprim

Toshiyuki Murase; Patchara Phuektes; Hiroichi Ozaki; Sunpetch Angkititrakul

doi:10.1016/j.psj.2021.101538

Prevalence of qnrS-positive Escherichia coli from chicken in Thailand and possible co-selection of isolates with plasmids carrying qnrS and trimethoprim-resistance genes under farm use of trimethoprim

Poult Sci. 2022 Jan;101(1):101538. doi: 10.1016/j.psj.2021.101538. Epub 2021 Oct 12.

Authors

Toshiyuki Murase¹, Patchara Phuektes², Hiroichi Ozaki³, Sunpetch Angkititrakul⁴

Affiliations

¹ Laboratory of Veterinary Microbiology, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan; The Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan. Electronic address: murase@tottori-u.ac.jp.
² Faculty of Veterinary Medicine, Khon Kaen University, 40002, Thailand; Research Group of Emerging and Reemerging Infectious Diseases in Animals and Zoonotic Diseases, Faculty of Veterinary Medicine, Khon Kaen University, 40002, Thailand.
³ Laboratory of Veterinary Microbiology, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan; The Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, Tottori 680-8553, Japan.
⁴ Faculty of Veterinary Medicine, Khon Kaen University, 40002, Thailand.

Abstract

One hundred and twenty chicken samples from feces (n = 80), the carcass surface at slaughter at 2 meat chicken farms (n = 20), and retail chicken meat from 5 markets (n = 20) collected during 2018 and 2019 were examined for the prevalence of plasmid-mediated quinolone resistance (PMQR) in Escherichia coli. We detected qnrS-positive E. coli in a total of 74 samples from feces (n = 59), the carcass surface (n = 7), and retail meat (n = 8). These 74 qnrS-positive isolates were tested for antimicrobial susceptibility to determine the minimum inhibitory concentrations (MICs) of certain antimicrobials and genetically characterized. Ampicillin-resistance accounted for 71 of the 74 isolates (96%), followed by resistance to oxytetracycline (57/74; 77%), enrofloxacin (ERFX) (56/74; 76%), sulfisoxazole (SUL) (56/74; 76%), trimethoprim (TMP) (49/74; 66%), and dihydrostreptomycin (48/74; 65%). All farm-borne SUL- and TMP-resistant isolates except one were obtained from samples from farm A where a combination of sulfadiazine and TMP was administered to the chickens. Concentrations of ERFX at which 50 and 90% of isolates were inhibited were 2 μg/mL and 32 μg/mL, respectively. Diverse pulsed-field gel electrophoresis (PFGE) patterns of XbaI-digested genomic DNA were observed in the qnrS-positive isolates from fecal samples. Several isolates from feces and the carcass surface had identical XbaI-digested PFGE patterns. S1-nuclease PFGE and Southern blot analysis demonstrated that 7 of 11 dfrA13-positive fecal isolates carried both the qnrS and dfrA13 genes on the same plasmid, and 2 of 3 dfrA1-positive isolates similarly carried both qnrS and dfrA1 on the same plasmid, although the PFGE patterns of XbaI-digested genomic DNA of the isolates were different. These results suggest that the qnrS gene is prevalent in chicken farms via horizontal transfer of plasmids and may partly be co-selected under the use of TMP.

Keywords: Escherichia coli; chicken; plasmid-mediated quinolone resistance; qnrS; trimethoprim.

MeSH terms

Animals
Chickens*
Escherichia coli / genetics
Escherichia coli Proteins* / genetics
Farms
Plasmids / genetics
Prevalence
Thailand
Trimethoprim / pharmacology

Substances

Escherichia coli Proteins
Qnr protein, E coli
Trimethoprim