Abstract:
The study determined the antimicrobial resistance (AMR) profiles of Listeria spp. (L. monocytogenes, L. innocua,
and L. welshimeri) recovered from beef and beef products sold at retail outlets in Gauteng Province, South
Africa. A total of 112 isolates of Listeria spp., including L. monocytogenes (37), L. innocua (65), and L. welshimeri
(10), were recovered from beef and beef products collected from 48 retail outlets. Listeria spp. was recovered by
direct selective plating following selective enrichment, and PCR was used to confirm and characterize recovered
isolates. The disc diffusion method determined the resistance to 16 antimicrobial agents. All 112 isolates
of Listeria spp. exhibited resistance to one or more antibiotics (P < 0.05). The prevalence of AMR in Listeria
isolates was high for nalidixic acid (99.1%) and cefotaxime (80.4%) but low for gentamycin (2.7%),
sulfamethoxazole‐trimethoprim (3.6%), azithromycin (5.4%), and doxycycline (6.3%). Overall, for the three
species of Listeria, the prevalence of resistance varied significantly only for streptomycin (P=0.016) and tetracycline
(P = 0.034). Multidrug‐resistant isolates were detected in 75.7% (28/37), 61.5% (40/65), and 80%
(8/10) isolates of L. monocytogenes, L. innocua, and L. welshimeri, respectively. The prevalence of AMR was significantly
affected by the location and size of retail outlets, type of beef and beef products, and serogroups of L.
monocytogenes. The high prevalence of AMR, particularly among the L. monocytogenes isolates, poses potential
therapeutic implications for human consumers of contaminated beef products. There is, therefore, a need to
regulate and enforce the use of antimicrobial agents in humans and animals in South Africa.
