Prevalence, antimicrobial resistance, and genomic characterization of non-typhoidal Salmonella in Thai native Blackbone chickens

Vet World Vol.19 February-2026 Article - 3

Research Article

Veterinary World, 19(2): 493-510

https://doi.org/10.14202/vetworld.2026.493-510

Kanit Assawatheptawee¹, Anong Kiddee², Uttapoln Tansawai³, Taradon Luangtongkum⁴, and Pannika R. Niumsup^1,5

1. Department of Microbiology and Parasitology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand.

2. Division of Microbiology and Parasitology, School of Medical Sciences, University of Phayao, Phayao, 56000, Thailand.

3. Department of Science, Faculty of Science and Agricultural Technology, Rajamangala University of Technology Lanna Phitsanulok, Phitsanulok, 65000, Thailand.

4. Department of Veterinary Public Health, Faculty of Veterinary Science, Chulalongkorn University, Bangkok, 10330, Thailand.

5. Center of Excellence in Medical Biotechnology, Faculty of Medical Science, Naresuan University, Phitsanulok, 65000, Thailand. .

Background and Aim: Native Blackbone chickens (Gallus gallus domesticus) are increasingly consumed in Southeast Asia because of their perceived health benefits. However, information on the epidemiology, antimicrobial resistance (AMR), and genomic characteristics of non-typhoidal Salmonella associated with this traditional poultry system remains limited. This study aimed to determine the prevalence, serovar distribution, antimicrobial susceptibility patterns, and genomic features of Salmonella isolated from feces and meat of Thai native Blackbone chickens.

Materials and Methods: A prospective longitudinal study was conducted between August 2020 and July 2021 on a small-scale Blackbone chicken farm in Phitsanulok province, Thailand. A total of 2,258 samples, comprising 1,755 fecal and 503 meat samples, were collected from chickens aged 1–50 weeks. Salmonella isolation was performed using standard culture and biochemical methods, with confirmation by invA using polymerase chain reaction. Serovars were determined by slide agglutination. Antimicrobial susceptibility was assessed against 14 antimicrobial agents using disk diffusion and broth microdilution methods. Six representative isolates were subjected to whole-genome sequencing (WGS) for multilocus sequence typing, detection of AMR and virulence genes, plasmid analysis, and phylogenetic comparison.

Results: The overall prevalence of Salmonella was 6.3% (142/2,258), with detection rates of 4.7% in fecal samples and 11.9% in meat samples. Salmonella Bovismorbificans was the predominant serovar (64.1%), followed by S. Corvallis (20.4%) and S. Weltevreden (9.2%). More than half of the isolates (52.8%) exhibited resistance to at least one antimicrobial, most commonly streptomycin (46.5%), while resistance to critically important antimicrobials was not observed. Multidrug resistance (MDR) was rare (1.4%). WGS revealed that S. Bovismorbificans isolates belonged to sequence type ST1499, whereas S. Weltevreden was identified as ST365. Despite limited AMR, all sequenced isolates carried numerous virulence-associated genes linked to adhesion, invasion, and intracellular survival.

Conclusion: Thai native Blackbone chickens harbor non-typhoidal Salmonella, including emerging and potentially invasive lineages, with low levels of MDR but substantial virulence potential. These findings highlight the zoonotic risk posed by traditional poultry systems and underscore the importance of continued surveillance and genomic monitoring to support food safety and One Health strategies.

Keywords: antimicrobial resistance, Blackbone chicken, food safety, genomic characterization, native poultry, non-typhoidal Salmonella, poultry meat, prevalence, Salmonella Bovismorbificans, Salmonella Weltevreden, Thailand, whole-genome sequencing, zoonotic pathogens.

How to cite this article: Assawatheptawee K, Kiddee A, Tansawai U, Luangtongkum T, Niumsup PR. Prevalence, antimicrobial resistance, and genomic characterization of non-typhoidal Salmonella in Thai native Blackbone chickens. Vet World. 2026;19(2):493–510.

Received: 19-07-2025 Accepted: 16-12-2025 Published online: 10-02-2026

Corresponding author: Pannika R. Niumsup E-mail: pannikan@nu.ac.th

DOI: 10.14202/vetworld.2026.493-510

Copyright: Assawatheptawee, 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.