Isolation and characterisation of colistin-resistant Enterobacterales from chickens in Southeast Nigeria

M. U. Anyanwu, R. Marrollo, M. Paolucci, F. Brovarone, P. Nardini, K. F. Chah, S. V.O. Shoyinka, E. Carretto

Research output: Contribution to journalArticlepeer-review


Objectives: Resistance to colistin (CST) mediated by mobile genetic elements has had a broad impact worldwide. There is an intensified call for epidemiological surveillance of mcr in different reservoirs to preserve CST for future generations. In Nigeria, the poultry industry is a key livestock sector. This study was undertaken to screen putative colistin-resistant Enterobacterales (CST-r-E) from poultry birds in Southeast Nigeria and to determine the genetic relatedness of mcr-harbouring isolates. Methods: Faecal and cloacal swab samples (n = 785) were collected from chickens in 17 farms located in three contiguous states in Southeast Nigeria between March–November 2018. Following selective culture, CST-r-E were isolated. Confirmation of CST resistance, antimicrobial susceptibility testing, molecular detection of genes mcr-1 to mcr-10, multilocus sequence typing (MLST) and randomly amplified polymorphic DNA (RAPD) analysis were performed on the isolates. A questionnaire was distributed to investigate the knowledge about CST and its use of chicken farm caretakers. Results: Of the 785 samples evaluated, 45 (5.7%) were positive for 48 CST-r-E, among which 23 harboured the mcr-1 gene (22 Escherichia coli and 1 Klebsiella pneumoniae). In two E.coli isolates, a new allelic variant (mcr-1.22) was detected. RAPD analysis allowed the identification of 11 different fingerprints. MLST also revealed 11 STs, with 3 of them being novel. Conclusion: mcr has significantly spread in poultry birds of Southeast Nigeria, which poses a worrisome risk to veterinary and human health. Strategies to prevent indiscriminate use of CST in farms should be quickly adopted before CST resistance becomes a huge global health issue.

Original languageEnglish
Pages (from-to)93-100
Number of pages8
JournalJournal of Global Antimicrobial Resistance
Publication statusPublished - Sep 2021


  • Antimicrobial resistance
  • Enterobacterales
  • mcr-1
  • mcr-1.22
  • Mobile colistin resistance
  • Nigeria

ASJC Scopus subject areas

  • Microbiology
  • Immunology and Allergy
  • Immunology
  • Microbiology (medical)


Dive into the research topics of 'Isolation and characterisation of colistin-resistant Enterobacterales from chickens in Southeast Nigeria'. Together they form a unique fingerprint.

Cite this