PLoS ONE (Jan 2023)

Assessing the mechanisms of multi-drug resistant non-typhoidal Salmonella (NTS) serovars isolated from layer chicken farms in Nigeria.

  • Idowu Oluwabunmi Fagbamila,
  • Elena Ramon,
  • Antonia A Lettini,
  • Maryam Muhammad,
  • Alessandra Longo,
  • Keti Antonello,
  • Mabel K Aworh,
  • Jacob K P Kwaga,
  • Paul A Abdu,
  • Jarleth U Umoh,
  • Junaidu A Kabir,
  • Antonia Ricci,
  • Lisa Barco

DOI
https://doi.org/10.1371/journal.pone.0290754
Journal volume & issue
Vol. 18, no. 9
p. e0290754

Abstract

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BackgroundIn Nigeria, there have been reports of widespread multiple antimicrobial resistance (AMR) amongst Salmonella isolated from poultry. To mitigate the impact of mortality associated with Salmonella on their farms, farmers resort to the use of antimicrobials without sound diagnostic advice. We conducted this study to describe the AMR patterns, mechanisms and genetic similarities within some Salmonella serovars isolated from different layer farms.MethodWe determine the AMR profiles of two hundred Salmonella isolates, selected based on frequency, serovar, and geographical and sample type distribution. We also assessed the mechanisms of multi-drug resistance for specific genetic determinants by using PCR protocols and gene sequence analysis. Pulsed-field gel electrophoresis (PFGE) was conducted on seven selected serovars to determine their genetic relatedness.ResultsOf 200 isolates, 97 (48.5%) revealed various AMR profiles, with the multiple antibiotic resistance (MAR) index ranging from 0.07-0.5. Resistance to ciprofloxacin was common in all the multi-drug resistant isolates, while all the isolates were susceptible to cefotaxime, ceftazidime, and meropenem. Genotypic characterization showed the presence of resistance genes as well as mutations in the nucleotide genes with subsequent amino acid substitutions. Fifteen isolates (43%) of S. Kentucky were indistinguishable, but were isolated from four different states in Nigeria (Ogun, n = 9; Kaduna, n = 6; Plateau, n = 3, and: Bauchi, n = 2). PFGE revealed 40 pulsotype patterns (Kentucky, n = 12; Larochelle, n = 9; Virchow, n = 5; Saintpaul, n = 4; Poona, n = 3; Isangi, n = 2, and; Nigeria, n = 2).ConclusionThis study recorded strictly related but diversely distributed Salmonella serovars with high AMR rates in poultry. We recommend strict regulation on antimicrobial use and regular monitoring of AMR trends among bacteria isolated from animals and humans to inform public policy.