ABSTRACT

Background and Aim: Salmonella is an important foodborne pathogen associated with livestock and contamination of meat during slaughter and processing. Cattle may harbor Salmonella without apparent clinical signs, creating opportunities for carcass contamination and subsequent entry into the food chain. This study aimed to determine the occurrence, serotype distribution, and antimicrobial resistance profiles of Salmonella recovered from paired fecal and carcass samples of slaughtered cattle in Algeria and to assess contamination patterns within paired samples.

Materials and Methods: A cross-sectional study was conducted on 319 cattle at two slaughterhouses in Algiers, Algeria. Paired fecal and carcass samples were collected from each animal, yielding 638 samples. Salmonella isolation and identification were performed using bacteriological procedures, followed by serotyping of recovered isolates. Antimicrobial susceptibility was evaluated phenotypically against the antimicrobial agents included in the study, and multidrug resistance (MDR) was assessed. Results from paired fecal and carcass samples were compared to characterize the distribution of Salmonella at the animal level.

Results: Salmonella was detected in 48/638 (7.52%) samples, corresponding to 44/319 (13.8%) cattle with at least one positive sample. Positive isolates were recovered from both fecal and carcass samples, demonstrating the presence of Salmonella at slaughter and contamination of carcass surfaces. Salmonella Anatum was the predominant serotype among the recovered isolates. Paired sample findings showed discordance between fecal and carcass positivity in several animals, indicating that fecal detection alone did not fully reflect carcass contamination status. Antimicrobial susceptibility profiles varied among serotypes. Of particular concern, all six Salmonella Kentucky isolates exhibited MDR phenotypes, including resistance to fluoroquinolones.

Conclusion: The detection of Salmonella in slaughtered cattle and on carcass surfaces highlights its relevance to meat hygiene and food safety in Algeria. The paired sampling approach provided complementary information on intestinal carriage and carcass contamination and represents a major strength of the study. The occurrence of MDR S. Kentucky, particularly with fluoroquinolone resistance, emphasizes the need for strengthened slaughter hygiene, integrated antimicrobial resistance surveillance, and molecular characterization of resistant isolates to clarify their genetic relatedness and potential transmission pathways.

Keywords: antimicrobial resistance, carcass contamination, cattle, food safety, multidrug resistance, paired sampling, Salmonella, slaughterhouse.