Fuente: Microorganisms - Revista científica (MDPI) Microorganisms, Vol. 14, Pages 850: Serovars, Genetic Relatedness and Antimicrobial Resistance of Non-Typhoidal Salmonella in Poultry and Farm Workers in Southeastern Nigeria
Microorganisms doi: 10.3390/microorganisms14040850
Authors:
Ifeyinwa R. Okosi
Onyinye J. Okorie-Kanu
Lynda Majesty-Alukagberie
Chinazom M. Eze
Chidiebere Anyaoha
Obichukwu C. Nwobi
Onyinye Onwumere-Idolor
Temitope M. Ogunniran
George N. Anosa
Toyin Olubade-Olatokunbo
Onyemaechi Ugboh
Simeon C. Okafor
Obianuju Okoroafor
Nkechi H. Ikena-Ezeh
Uju C. Okafor
Madubuike U. Anyanwu
Charles Odilichukwu R. Okpala

Non-typhoidal Salmonella (NTS) is an important poultry-associated pathogen with major One Health and economic impacts, but data on its epidemiology and antimicrobial resistance in Nigeria remain limited. This study investigated the prevalence, serovar distribution, clonal relatedness, and antimicrobial resistance of NTS along the poultry production chain in Enugu State, southeastern Nigeria. A total of 2400 samples were collected, comprising feces (cecal content)/cloacal swabs from chickens (n = 1100), eggs (n = 400), chicken meat (n = 600), and stool samples from poultry workers (n = 300). Isolation and identification were performed using standard bacteriological methods, with confirmation by serotyping and polymerase chain reaction (PCR) targeting the invA gene. Genetic relatedness was assessed using enterobacterial repetitive intergenic consensus (ERIC)-PCR, and antimicrobial susceptibility was determined by the disk diffusion method. Overall, 47 (2.0%) Salmonella enterica isolates were recovered from 2400 samples, with the highest prevalence observed in eggs (3.5%), followed by human stool (3.3%), chicken meat (1.8%), and chicken feces (1.1%). Only 35 (11.8%) of the 297 sampled farms were positive for Salmonella, and recovery rates differed significantly (p = 0.0065) among sample sources. Five serotypes were identified, dominated by S. Typhimurium (57.4%), followed by S. Enteritidis (14.9%), S. Anatum (12.8%), S. Stanley (8.5%), and S. Agona (6.3%). ERIC-PCR revealed multiple clonal clusters, many containing isolates from mixed sources, indicating circulation of related strains between poultry and humans. All isolates were resistant to ampicillin, with high resistance to tetracycline (76.6%), sulphamethoxazole–trimethoprim (51.1%), and fluoroquinolones. Overall, 80.9% of isolates were multidrug-resistant, with a mean Multiple Antibiotic Resistance Index of 0.29, highest among isolates from chicken feces. Although the prevalence of NTS was low, the presence of genetically related multidrug-resistant strains across the production chain underscores the role of poultry as a reservoir for zoonotic transmission and highlights the need for coordinated One Health surveillance and antimicrobial stewardship strategies in Nigeria.