Prevalence, Virulence and Antimicrobial Resistance Profiles of Listeria monocytogenes in Raw Cow’s Milk from Côte d’Ivoire: Implications for Food Safety

Abstract

Aims: The consumption of raw milk, although widespread, is a major public health concern due to the risk of contamination by pathogenic microorganisms. The aim of this study was to characterise the Listeria monocytogenes strains isolated from raw cow’s milk in Côte d’Ivoire. Methodology: For this purpose, 144 samples of raw cow’s milk were collected from the three main production regions (Abidjan, Bouaké and Korhogo). Listeria spp. were isolated and then identified using PCR-based methods, followed by sequencing of the 16S rDNA region to confirm species identification. The virulence genes (prfA, hly and actA) and antimicrobial resistance of the Listeria monocytogenes isolates were determined. Results: Listeria monocytogenes was detected in 18 of 144 raw cow’s milk samples, corresponding to an overall prevalence of 12.5%. Each virulence gene was detected in 13 (72.2%) of the 18 strains tested, and 11 strains (61.1%) exhibited a complete virulence profile. Antibiotic resistance varied according to the antibiotic class. Resistance to erythromycin, a macrolide, was observed in 44.4% of the strains, while 55.6% exhibited resistance to trimethoprim–sulfamethoxazole. Among the β-lactams, 33.3% of the strains were resistant to ampicillin. In contrast, the particularly high resistance rate to meropenem (94.4%) observed among the tested strains is concerning and warrants particular attention. Conclusion: The detection of L. monocytogenes in raw cow’s milk marketed in Côte d’Ivoire, together with the high prevalence of antimicrobial resistance observed among the tested strains, highlights the potential role of raw milk as a vehicle for the transmission of pathogenic and antimicrobial-resistant bacteria. Regular microbiological surveillance and the implementation of good hygienic practices are essential to improve the microbiological safety of raw milk and dairy products.