Abstract:
Listeria monocytogenes is an important foodborne pathogen which has the ability to
adapt and survive in food and food processing facilities where it can persist for years.
In this study, a total of 143 L. monocytogenes isolates in South Africa (SA) were
characterized for their strain’s genetic relatedness, virulence profiles, stress tolerance
and resistance genes associated with L. monocytogenes. The Core Genome Multilocus
Sequence Typing (cgMLST) analysis revealed that the most frequent serogroups were
IVb and IIa; Sequence Types (ST) were ST204, ST2, and ST1; and Clonal Complexes
(CC) were CC204, CC1, and CC2. Examination of genes involved in adaptation and
survival of L. monocytogenes in SA showed that ST1, ST2, ST121, ST204, and
ST321 are well adapted in food processing environments due to the significant overrepresentation
of Benzalkonium chloride (BC) resistance genes (bcrABC cassette,
ermC, mdrL and Ide), stress tolerance genes (SSI-1 and SSI-2), Prophage (0) profiles
(LP_101, vB LmoS 188, vB_LmoS_293, and B054 phage), plasmids profiles (N1-
011A, J1776, and pLM5578) and biofilm formation associated genes. Furthermore,
the L. monocytogenes strains that showed hyper-virulent potential were ST1, ST2
and ST204, and hypo-virulent were ST121 and ST321 because of the presence and
absence of major virulence factors such as LIPI-1, LIPI-3, LIPI-4 and the internalin gene
family members including inlABCEFJ. The information provided in this study revealed
that hyper-virulent strains ST1, ST2, and ST204 could present a major public health risk
due to their association with meat products and food processing environments in SA.
