Impact of marbofloxacin administration on the emergence of marbofloxacin-resistant E. coli in faecal flora of goats and elucidation of molecular basis of resistance

Pallavi Bhardwaj; Gurpreet Kaur; S Rampal

doi:10.1016/j.jgar.2020.03.019

Impact of marbofloxacin administration on the emergence of marbofloxacin-resistant E. coli in faecal flora of goats and elucidation of molecular basis of resistance

J Glob Antimicrob Resist. 2020 Jun:21:116-123. doi: 10.1016/j.jgar.2020.03.019. Epub 2020 Apr 14.

Authors

Pallavi Bhardwaj¹, Gurpreet Kaur², S Rampal³

Affiliations

¹ Department of Veterinary Pharmacology and Toxicology, Dr. G.C. Negi College of Veterinary and Animal Sciences, CSK H.P. Agricultural University, Palampur, H.P., India; Department of Veterinary Pharmacology and Toxicology, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India. Electronic address: pallavivet@gmail.com.
² Department of Veterinary Microbiology, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India.
³ Department of Veterinary Pharmacology and Toxicology, Guru Angad Dev Veterinary and Animal Sciences University, Ludhiana, Punjab, India.

PMID: 32302733
DOI: 10.1016/j.jgar.2020.03.019

Abstract

Objectives: The level of resistance immediately prior to slaughter in food-producing animals is of great public health significance because of likely transmission of resistant bacteria via the food chain.

Methods: Marbofloxacin was administered to goats at the dose of 2 mg/kg body weight by intramuscular route for 5 days. Faecal Escherichia coli population was monitored and examined for bacteriological procedures. DNA sequencing of gyrA and parC genes was performed to identify mutations at quinolone-resistance determining region, and interaction between marbofloxacin and GyrA was studied by in silico docking. E. coli isolates were screened for plasmid-mediated quinolone resistance genes qnrA, qnrB, qnrS, aac(6')Ib-cr, qepA, oqxA and oqxB. Efflux pump-mediated resistance was evaluated by ethidium bromide assay, reduction in minimum inhibitory concentration (MIC) values in the presence of efflux pump inhibitors and relative expression of AcrAB-TolC efflux pump.

Results: During the treatment period, emergence of marbofloxacin-resistant E. coli strains was observed in gut flora. Quinolone resistance determining regions (QRDRs) in gyrA identified amino acid codon mutations Ser83Leu and Asp87Asn, and Ser80Ile in parC. Docking analysis implied that marbofloxacin could not form strong complexes with mutated DNA-gyrase. A high prevalnce of PMQR genes, especially qnrS, was observed along with overexpression of AcrAB-TolC efflux pump.

Conclusions: The study highlighted the high prevalence of transferable mechanisms of quinolone resistance and over expression of efflux pumps in marbofloxacin-resistant E. coli isolates apart from classic QRDR mutations. The present study recommends to consider the period of dominance of resistant commensals, being excreted by animals during the antimicrobial treatments, while formulating the withdrawal period for drugs, especially in food-producing animals.

Keywords: AcrAB-TolC efflux pump; E. coli; Marbofloxacin; QRDR mutations.

MeSH terms

Animals
DNA Gyrase / genetics
Escherichia coli* / genetics
Fluoroquinolones / pharmacology
Goats*

Substances

Fluoroquinolones
marbofloxacin
DNA Gyrase