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Pathogenic food-borne bacteria have been associated with severe morbidity and mortality in humans and animals. This study was aimed at determining the prevalence of Staphylococcus aureus, Salmonella spp., and Escherichia coli present in cattle and pigs slaughtered in selected abattoirs in Vhembe District and at determining the susceptibility of the isolates to antibiotics. A total of 176 swab samples (28 cattle and 16 pigs) of the rump, flank, brisket, and neck of the animals were analyzed using standard microbiological methods. E. coli isolates were genotyped to detect pathogenic strains. Of the 176 samples, 104 (67.5%) were positive for E. coli and 50 (32.5%) for S. aureus. There was no statistically significant difference (P>0.05) in the isolation rate from the different animal parts or abattoirs. Overall, 14/104 (13.46%) of the E. coli isolates were pathogenic strains which included enteropathogenic E. coli (EPEC) (bfpA) 1.9%, enterotoxigenic E. coli (ETEC) (LT) 3.8%, and enteroaggregative E. coli (EAEC) (aaiC) 7.6%. E. coli isolates were resistant (100%) to vancomycin and bacitracin. S. aureus (100%) were resistant to oxacillin and nalidixic acid. The presence of resistant strains of these bacteria in food of animal origin could serve as important vehicles transmitting these bacteria to humans. This finding is of epidemiological significance.

We assessed the in vitro antimicrobial activity of Peltophorum africanum by means of the agar well and macrodilution methods. The toxicity on a normal human liver cell (Chang liver cell) was determined using the CellTiter-Blue cell viability assay, and the compounds contained in the fractions were identified using GC-MS. Zone diameter of inhibition of the extract ranged from 12.5±0.7 to 32 ± 2.8 mm for bacteria and from 7.5 ± 0.7 to 26.4 ± 3.4 mm for yeast. Marked activity of the extract was observed against Plesiomonas shigelloides ATCC 51903, with MIC and MLC values of 0.15625 and 0.3125 mg/mL, respectively. The extract was both bactericidal (MICindex≤2) and bacteriostatic/fungistatic (MICindex>2) in activity. Lethal dose at 50 (LD50) showed 82.64±1.40 degree of toxicity at 24 hrs, and 95 percentile of cell death dose activity ranged from log 3.12±0.01 to 4.59±0.03. The activity of the eight fractions tested ranged from 1.0±0.5 to 3.7±1.6 mg/mL (IC50) and from 2.1±0.8 to 6.25±0 mg/mL (IC90). The extract was toxic to human Chang liver cell lines.

The present study was carried out to investigate the potential of Listeria ivanovii isolates to exist as biofilm structures. The ability of Listeria ivanovii isolates to adhere to a surface was determined using a microtiter plate adherence assay whereas the role of cell surface properties in biofilm formation was assessed using the coaggregation and autoaggregation assays. Seven reference bacterial strains were used for the coaggregation assay. The degree of coaggregation and autoaggregation was determined. The architecture of the biofilms was examined under SEM. A total of 44 (88%) strains adhered to the wells of the microtiter plate while 6 (12%) did not adhere. The coaggregation index ranged from 12 to 77% while the autoaggregation index varied from 11 to 55%. The partner strains of S. aureus, S. pyogenes, P. shigelloides, and S. sonnei displayed coaggregation indices of 75% each, while S. Typhimurium, A. hydrophila, and P. aeruginosa registered coaggregation indices of 67%, 58%, and 50%, respectively. The ability of L. ivanovii isolates to form single and multispecies biofilms at 25°C is of great concern to the food industry where these organisms may adhere to kitchen utensils and other environments leading to cross-contamination of food processed in these areas.