Prevalence and serotype diversity of non-typhoidal Salmonella in foods and animal feces: a cross-sectional study in Greater Accra, Ghana

Foodborne non-typhoidal Salmonella (NTS) infections are a major global health issue, frequently linked to animal source foods. However, there is limited data on NTS prevalence, distribution, and serotype diversity in common animal products and related food in Ghana. This study investigated the prevalence and serotype diversity of NTS in animal source foods, ready-to-eat (RTE) food, and animal fecal samples across six districts in the Greater Accra Region of Ghana. Methods: A total of 696 samples were randomly collected from selected markets across the districts. These included unprocessed animal products: beef (16), chicken (21), eggs (185), and raw cow milk (40). Additionally, 50 samples of RTE street foods and 36 samples of locally produced soft cheese (“wagashie”) were obtained from vendors. Fecal samples consisted of chicken droppings (70) and pig feces (138), which were purposively collected from 11 poultry farms and two pig slaughter facilities in the region. Furthermore, 140 pork samples were purposively collected from the slaughter facilities. Standard microbiological methods, including pre-enrichment, selective enrichment, and plating on selective media, were used for Salmonella species isolation, with identification confirmed by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Serotyping followed the White-Kauffman Le-Minor classification scheme. Results: Overall, 26 Salmonella isolates were recovered (3.7%). Prevalence was significantly higher in animal source foods (5.71%; 25/438) compared to fecal samples (0.4%; 1/208) (p = 0.0026). Salmonella contamination was highest in raw pork (13.6%), followed by “wagashie” (5.5%) and raw milk (5%). Nine distinct serotypes were identified. Among them, Salmonella Typhimurium was the most prevalent, accounting for 40.9%, followed by Salmonella Kaapstad at 13.6%. Additionally, pork samples contained seven of these serotypes. Conclusions: These findings highlight a potential risk posed by NTS in commonly consumed animal source foods in Greater Accra and emphasize the need for targeted interventions to control contamination, particularly in pork products.