A comparative study on the occurrence, risk factors, and genetic characteristics of Listeria species recovered from cattle farms, and beef abattoirs in Gauteng Province, South Africa

Abstract

Abstract These cross-sectional reported the occurrence, risk factors, and genetic characteristics of Listeria species recovered from cattle farms and beef abattoirs in Gauteng Province, South Africa. A total of 328 samples collected from 23 cattle farms and 262 samples from 8 beef abattoirs were processed using standard bacteriological and molecular methods to detect Listeria spp. The factors associated with the prevalence of Listeria spp. were investigated, and multiplex polymerase chain reaction (mPCR) was used to determine Listeria species, the pathogenic serogroups, and carriage of eight virulence-associated genes by Listeria monocytogenes. The overall prevalence of Listeria spp. in cattle farms was 14.6%, comprising Listeria innocua (11.3%), Listeria monocytogenes (3.4%), Listeria welshimeri (0.0%) compared with 11.1%, comprising Listeria innocua (5.7%), Listeria monocytogenes (4.6%), Listeria welshimeri (0.8%) for beef abattoirs. Of the three variables (area, type of farm/abattoir, and sample type) investigated, only the sample types at abattoirs had a significant (P < 0.001) effect on the prevalence of L. innocua and L. welshimeri. The frequency of distribution of the serogroups based on 11 L. monocytogenes isolated from farms was 72.7% and 27.3% for the serogroup 1/2a-3a and 4b-4d-4e, respectively, while for the 12 L. monocytogenes isolates recovered from abattoirs, it was 25%, 8.3%, 50% and 16.7% for the serogroup 1/2a-3a, 1/2b-3b, 1/2c-3c, and 4b-4d-4e respectively (P < 0.05). All (100.0%) isolates of L. monocytogenes from the farms and abattoirs were positive for seven virulence genes (hlyA, inlB, plcA, iap, inlA, inlC, and inlJ). The clinical and food safety significance of the findings cannot be ignored.