Cross-domain antimicrobial resistance in poultry farming: A One Health assessment of antimicrobial use and multidrug resistance in Kiambu County, Kenya

Vet World Vol.19 January-2026 Article - 1

Research Article

Veterinary World, 19(1): 1-14

https://doi.org/10.14202/vetworld.2026.1-14

Ann Kangai Munene^1,2, Peter Muiruri Mwangi³, Lilly Caroline Bebora⁴, Christine Minoo Mbindyo⁴, and John Muthini Maingi⁵

1. Department of Biochemistry, Microbiology, and Biotechnology, Kenyatta University, Nairobi, Kenya.

2. Department of Veterinary Pathology, Microbiology, and Parasitology, University of Nairobi, Nairobi, Kenya.

3. International Center of Insect Physiology and Ecology, Nairobi, Kenya.

4. Department of Veterinary Pathology, Microbiology, and Parasitology, University of Nairobi, Nairobi, Kenya.

5. 1. Department of Biochemistry, Microbiology, and Biotechnology, Kenyatta University, Nairobi, Kenya.

Background and Aim: Antimicrobial resistance (AMR) has emerged as a major One Health threat driven by inappropriate antimicrobial use (AMU) in humans, animals, and the environment. Poultry production is recognized as a key reservoir of antimicrobial-resistant bacteria, yet few studies in Kenya examine AMU and AMR across interconnected human–animal–environment domains. This study assessed AMU patterns among poultry farmers in Kiambu County and characterized phenotypic resistance in Escherichia coli and Enterococcus spp. isolated from humans, chickens, and chicken environments.

Materials and Methods: A cross-sectional study was conducted from May to September 2024, involving 102 poultry farms. Farm demographics and AMU data were collected using a semi-structured questionnaire. Archived E. coli (n = 92) and Enterococcus spp. (n = 101) isolates from chicken handlers’ hands, chickens, and environmental samples were subjected to antimicrobial susceptibility testing using the Kirby–Bauer method per Clinical and Laboratory Standards Institute (CLSI) 2024 guidelines. Descriptive and inferential statistics, including logistic regression with false discovery rate correction, were used to assess associations between AMU and phenotypic resistance.

Results: Macrolides (69%), tetracyclines (48%), and sulfonamides (21%) were the most commonly used antimicrobials; 7% of farms reported colistin use. Among E. coli isolates, resistance was highest to ampicillin (77%), tetracycline (72%), and trimethoprim–sulfamethoxazole (49%), with 35% exhibiting multidrug resistance (MDR). No carbapenem resistance was detected. Enterococcus isolates showed high erythromycin resistance (61%) and moderate ciprofloxacin resistance (26%), with 6.9% exhibiting MDR; no vancomycin-resistant enterococci (VRE) were observed. Penicillin use strongly predicted ampicillin resistance in both organisms, whereas sulfonamide use was associated with reduced trimethoprim–sulfamethoxazole resistance. Macrolide use did not correlate with erythromycin resistance.

Conclusion: High AMU in poultry farming, particularly of macrolides, tetracyclines, and sulfonamides, has created significant selection pressure, contributing to MDR emergence across One Health interfaces. Detection of resistance in humans, poultry, and shared environments underscores the bidirectional risk of AMR transmission. Strengthened antimicrobial stewardship, regulation of critically important antimicrobials, and enhanced farm hygiene are essential to mitigate AMR. These findings directly support Kenya’s Vision 2030 and SDGs targeting health, responsible production, and environmental protection.

Keywords: Antimicrobial use, antimicrobial resistance, poultry farming, Escherichia coli, Enterococcus, One Health, Kenya.

How to cite this article: Munene AK, Mwangi PM, Bebora LC, Mbindyo CM, Maingi JM. Cross-domain antimicrobial resistance in poultry farming: A One Health assessment of antimicrobial use and multidrug resistance in Kiambu County, Kenya. Vet World. 2026; 19(1): 1–14.

Received: 21-08-2025 Accepted: 09-12-2025 Published online: 06-01-2026

Corresponding author: Ann Munene E-mail: annkmunene@gmail.com

DOI: 10.14202/vetworld.2026.1-14

Copyright: Munene, et al. This article is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http:// creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.