Isolation, discrimination, and molecular detection of Listeria species from slaughtered cattle in Namwala District, Zambia

Abstract

Background The food industry is increasingly becoming more scrutinized, given the frequency and intensity with which zoonotic diseases are being reported. Pathogen tracking has become more applicable with regards food safety. It is in this regard that the present study was formulated to track Listeria species. in freshly slaughtered cattle carcasses by utilizing standard and molecular biological techniques. Methods A cross-sectional study design was conducted from March to December 2020 with 200 samples being equally collected in the rainy and dry seasons. A total of 180 and 20 swabs were aseptically collected from carcasses and the environment respectively. Samples were first subjected to pre-enrichment in half-strength Fraser broth followed by enrichment in full strength Fraser broth and subsequent plating on Listeria agar. Listeria growth characteristics were identified up to species level based on their morphological and biochemical characteristics. Further, molecular detection and phylogenetic analysis was conducted. Quantitative proportionate survey data were analyzed using Stata Version 15 software to estimate crude prevalence taking into account complex design at abattoir level. Factors associated with contamination were characterized using logistic regression. Sequences were analyzed using, Genetyyx version 12 and phylogenetic Mega. Results Of the 200 samples, 19 were positive for Listeria species identified as L.innocua 14/19 (73.7%) and L. monocytogenes 5/19 (26.3%). All isolates were from freshly slaughtered carcasses, and none from environment. Siginificant differences in contamination levels were observed based on season: rainy season yielded 14 (73.6%) whilst the dry season 5 (26.3%). The L. monocytogenes strains showed a high degree of homogeneity on phylogenetic analysis and clustered based on abattoir. Seasonality was identified as a major determinant influencing contamination based on the final logistic regression model. Conclusion This study found evidence of L. monocytogenes contamination on traditionally raised beef carcasses across various abattoirs surveyed. The failure to find Listeria contamination on the abattoir environment may to a greater extent intimate cattle carccases as primary sources of contamination. However, a more comprerehnsive study incorporating different geographical regions is needed to conclusively ascertain these present findings.

Listeria monocytogenes in ready to eat meat products from Zambia: phenotypical and genomic characterization of isolates

“…Our findings highlighted the presence of L. monocytogenes mainly in ham and polony; the latter was the same type of product involved in the SA outbreak ( Smith et al, 2019 ). Previous studies conducted in Zambia reported the prevalence of L. monocytogenes in 74% of poultry dressed carcasses ( Mpundu et al, 2022a ) and 26.3% in cattle carcasses ( Mpundu et al, 2022b ).…”

Socio-Cultural Factors and Experiences of School Going Teenage Mothers in Rural Zambia: A Phenomenological Study

“…It is important to estimate the burden of teenage pregnancies in terms of prevalence and incidence, but this is only one aspect of the problem, as it does not put a ‘face’ to teenage mothers. Economic and socio-cultural factors influence the likelihood of a girl getting pregnant whilst still a teenager, and these may be missed in studies that focus on numbers such as prevalence and incidence (8, 10, 12, 17). Pregnancies occurring during the adolescent years have been associated with interference with the girl’s education.…”

Contrasting genes conferring short- and long-term biofilm adaptation in Listeria

“…L. monocytogenes is commonly isolated from animal hosts (cattle, sheep and birds) [7][8][9][10] and their food products (raw meat, pasteurized milk, fish) [11][12][13], as well as environmental sources, such as soil, vegetables, sewage and other water sources [14][15][16][17][18]. Consumption of any of these food sources can lead to infection of the host via translocation of the intestinal barrier, infection of the lymph nodes, and the pathogen subsequently entering the spleen and liver [19].…”