Prevalence, persistence and diversity of Listeria strains with antimicrobial resistance and virulence genes from fresh fruits in Southwest Nigeria

Abstract

Untreatable listeriosis and wastage could be traced to contaminated fruits. This study assessed Listeria spp , antimicrobial resistance and virulence genes in ready-for-sale fruits. Listeria spp was identified in 270 fruits: garden egg (90), tomato (90) and watermelon (90), were purchased from thirty markets, in Southwest Nigeria. Listeria spp were evaluated, identified and sequenced. Antimicrobial sensitivity assay (15 antibiotics), eighteen antimicrobial and nine virulence genes were screened for. Listeria spp 28 (100.00%) at 66.25 MPN/g comprising of pathogenic (19) ( L. monocytogenes 6 (21.43%) , L. ivanovii 5 (17.86%) , L. seegligeri 8 (28.57%)) and non-pathogenic (9) ( L. welshimeri 5 (17.86%) , L. grayi 2 (7.14%) and L. innocua 1 (3.57%)) strains were distributed in garden egg 8 (28.57% at 56.63 MPN/g), tomato 14 (50.00% at 54.29 MPN/g) and watermelon 6 (21.43% at 57.00 MPN/g). Carbapenem, chloramphenicol, macrolides, tetracycline and folate resistant Listeria strains with highest prevalence were in fruit from Balogun 9 (60.00%), Agege 8 (28.57%) and Lekki 10 (45.45%) in Lagos state. Virulent L. strains had five L. monocytogenes, two L. ivanovii, eight L. seegligeri, five L. welshimeri, two L. innocua and eight L. grayi in fruit from Lagos, Osun and Ondo States respectively. Listeria monocytogenes, L. ivanovii and L. seegligeri in fruit from Lagos State had prfA, plcA and plcB genes. Fruits could thereby be versatile route for various diverse virulent-resistant Listeria strains that could cause constant listeriosis and spoilage. However, there is need for more enforced, good and healthy handling of fruits on farms and in markets. • Pathogenic and non-pathogenic Listeria strains were found in fruits • The Listeria strains were carbapenem, chloramphenicol, macrolides, tetracycline and folate resistant • Pathogenic and non-pathogenic Listeria strains were with multiple virulenc genes • Listeria monocytogenes and L. grayi with acquired SHV and CTX genes is rare.