Two cross‐sectional studies determined the prevalence of antimicrobial resistance (AMR) in Listeria monocytogenes and Listeria spp. isolated from cattle farms in Mpumalanga and North West provinces in South Africa. A total of 100 isolates comprise 12 and 44 of L. monocytogenes and Listeria spp., respectively, from Mpumalanga province and 3 and 41 from North West province. The disc diffusion method was used to determine the isolates’ resistance to 16 antimicrobial agents. The studies also investigated the factors (district, farm type, and sample type) associated with AMR. All 100 isolates tested were resistant to at least one antimicrobial agent. Among the isolates of L. monocytogenes from Mpumalanga province, the prevalence of resistance ranged from 41.7% (doxycycline) to 100% (cefotaxime, kanamycin, streptomycin, and nalidixic acid), compared to from 33.3% (kanamycin, tetracycline, doxycycline, nalidixic acid, and enrofloxacin) to 100% (streptomycin, nalidixic acid, and ampicillin) in the North West province. Across both provinces, the prevalence of resistance varied significantly for amoxicillin–clavulanate ( p = 0.0110), kanamycin ( p = 0.0286), and azithromycin ( p = 0.0022). Among the Listeria spp., resistance ranged from 2.3% (cefotaxime) to 100% (nalidixic acid) in Mpumalanga province, compared to from 14.6% (sulfamethoxazole–trimethoprim, SXT) to 100% (nalidixic acid) in North West. For L. monocytogenes and Listeria spp. from both provinces, resistance to antimicrobial class was low for SXT (6.0%) and β‐lactams (9.7%) but comparatively high for lincosamides (50%) and fluoroquinolone (62.3%) ( p < 0.00001). Of the three factors (district, farm type, and sample type) investigated for their association with the prevalence of resistance in L. monocytogenes and Listeria spp. in both provinces, the district location of the farm was the only factor that statistically significantly ( p = 0.0455) affected the prevalence of resistance in L. monocytogenes to ciprofloxacin in only Mpumalanga province. Notably, on a larger geographic scale, Mpumalanga and North West provinces showed significant ( p < 0.05) differences in the prevalence of ampicillin resistance. The high prevalence of resistance to multiple antimicrobial agents across sources and the two provinces may pose therapeutic challenges for treating listeriosis on cattle farms.
Moabelo et al. (Thu,) studied this question.