Abstract. The objective of the current study was to determine the incidence of contamination by the top 7 Shiga toxinproducing Escherichia coli (STEC) O-groups, responsible for the majority of E. coli infections in human beings, in retail meat from different animal species. Samples from ground beef (n = 51), ground pork (n = 16), ground chicken (n = 16), and game meat (deer, wild boar, bison, and rabbit; n = 55) were collected from retail vendors for the detection of 7 STEC O-groups (O26, O45, O103, O111, O121, O145, and O157). Meat samples were tested by using a multiplex polymerase chain reaction assay targeting the wzx gene of O antigen gene clusters of the 7 STEC O-groups. The positive samples were further tested for Shiga toxin genes (stx1 and stx2). Out of a total of 83 ground beef, pork, and chicken samples, 17 (20%) carried O121, 9 (10%) carried O45, 8 (9%) carried O157, 3 (3%) carried O103, and 1 (1%) carried O145. None of the samples were positive for O26, O111, or the stx gene. All 3 white-tailed deer samples (100%) were positive for O45, O103, or both, 2 (10%) out of 20 red deer samples exhibited the presence of O103, and all 3 bison samples were contaminated with either O121, O145, or O157. One sample from ground deer, contaminated with E. coli O45, carried the stx1 gene. This preliminary investigation illustrates the importance of microbiological testing of pathogens in meat products, as well as the recognized need for increased surveillance and research on foodborne pathogens.

The caecal chyme of pigs was incubated anaerobically in McDougall buffer with and without fumonisin B1 (5 µg/ml) for 0, 24 and 48 h. The plate count agar technique was applied for the enumerating amount of bacteria including aerobic, anaerobic bacteria, coliform, Escherichia coli and Lactobacillus sp. The quantitative polymerase chain reaction was also performed to estimate the number of copies of the total bacteria, Lactobacillus, Bacteroides and Prevotella. No significant differences in the amount of bacteria groups between the experimental (buffer, chyme, and fumonisin B1) and control 1 groups (buffer + chyme) were observed in both methods. Fumonisin B1 and hydrolysed fumonisin B1 concentration were analysed by liquid chromatograghy – mass spectrometry. There was no significant difference in FB1 concentration between the experimental and the control 2 group (buffer and fumonisin B1) at 0 h incubation, 5.185 ±0.174 µg/ml compared with 6.433 ±0.076 µg/ml. Fumonisin B1 concentration in the experimental group was reduced to 4.080 ±0.065 µg/ml at 24 h and to 2.747 ±0.548 µg/ml at 48 h incubation and was significantly less than that of in the control group. Hydrolysed fumonisin B1 was detected after 24 h incubation (0.012 ±0 µg/ml). At 48 h incubation time, hydrolysed fumonisin B1 concentration was doubled to 0.024 ±0.004 µg/ml. These results indicate that fumonisin B1 can be metabolised by caecal microbiota in pigs though the number of studied bacteria did not change.

Fumonisin-producing fungal species, Fusarium verticillioides, culture was mixed in the diets of 6 piglets for 9 days (Fumonisin B1 [FB1] intake of 17 mg/kg) to investigate whether there is any potential alteration in the caecal bacterial communities between the experimental (with F. verticillioides) and control groups (without F. verticillioides). Plate count agar culturing technique was applied to measure the amount of aerobic and anaerobic bacteria, Escherichia coli, coliforms, Lactobacillus spp. and Clostridium perfringens. A significant difference was observed between the control and experimental group only in the case of aerobic bacteria on Day 4, 8.60 ± 0.22 compared to 8.06 ± 0.20 (P < 0.05), respectively. Quantitative polymerase chain reaction (qPCR) was performed to estimate the DNA copy number of total bacteria, Bacteroides and Prevotella spp., Clostridium spp., E. coli, Enterobacteriales, Firmicutes and Lactobacillus spp. Significant differences were observed between the control and experimental group regarding total bacteria on Day 2 and Day 6, Firmicutes on Day 2 and E. coli and Enterobacteriales on Day 4. Regarding the entire feeding time, no significant difference between the two groups was found in all species of investigated bacteria by the culturing technique and qPCR after an 8-day exposure. The present research contributes to the understanding of how microbiota responds to the FB1 load.