Prevalence of Listeria spp. and characterization of Listeria monocytogenes isolated from food products in Tetouan, Morocco

- High distribution of species of Listeria in food samples.
- No resistance to the reference treatment antibiotics.
- L. monocytogenes isolates were mainly from PCR serogroups IVb and IIa and from MLST CC2 and CC199.
- Three cgMLST clusters were detected underlying a possible common source of contamination.

A total of 1096 food samples were purchased in Tetouan, North-Western of Morocco, to examine the presence of Listeria spp. Eighty (7.3%) of the tested samples were found positive for the presence of Listeria spp., while L. monocytogenes was detected in 16 (1.5%) samples. L. monocytogenes isolates belonged to clonal complexes CC2 (PCR serogroup IVb) and CC199 (PCR serogroup IIa) and to 8 different combined AscI/ApaI pulsed-field gel electrophoresis profiles. Core genome multilocus sequence typing (cgMLST) allowed to distinguish 12 different cgMLST types and revealed the presence of 3 clusters of closely-related isolates from different samples, suggesting the existence of common sources of contamination. Isolates showed no resistance to the reference antibiotics used for the treatment of listeriosis. This study underlines the circulation of L. monocytogenes strains of clonal complex CC2 in Morocco and highlights the importance of microbiological surveillance in order to minimize consumers' exposure to this foodborne pathogen.