Listeria monocytogenes is pervasive in agricultural environments and difficult to eradicate from food-processing facilities. Consequently, various foods become contaminated, posing health risks to immunocompromised individuals. This surveillance study aimed to enhance the understanding of the genetic diversity, virulence, plasmid content, sanitizer tolerance, and antibiotic resistance of L. monocytogenes from ready-to-eat (RTE) hummus, fresh produce and food-processing environments in the Western Cape, South Africa (2018-2021). Sixty L. monocytogenes isolates were classified as lineage I or lineage II using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Lineage I was notably prevalent overall (57%; n = 34) and significantly associated with fresh produce (88%; n = 7) (p = 0.04). Whole-genome sequencing (WGS) and bioinformatic analysis characterized a subset of 20 L. monocytogenes isolates into seven sequence types (STs) (ST1, ST2, ST3, ST5, ST101, ST121, ST204), and three serotypes (1/2a, 1/2b, 4b). ST204 (38%; n = 3) was most prevalent in the food-processing environment, ST5 (50%; n = 3) in fresh produce, and ST5 (33%; n = 2), ST101 (33%; n = 2) and ST121 (33%; n = 2), in RTE hummus. However, no single serotype or ST was significantly overrepresented in any category (p > 0.05). All isolates carried both Listeria pathogenicity island (LIPI)-1 and LIPI-2 gene clusters. Two isolates (ST1 and ST3) contained all genes comprising LIPI-3. Two ST5 isolates from RTE hummus contained the tetM gene. Isolates from different origins contained the emrC, bcrABC or qacH genes conferring tolerance to benzalkonium chloride, a quaternary ammonium compound class of sanitizer. RTE hummus, fresh produce and the food-processing environment are susceptible to contamination by diverse and virulent L. monocytogenes strains.

Listeria monocytogenes is a concern in seafood and its food processing environment (FPE). Several outbreaks globally have been linked to various types of seafood. Genetic profiling of L. monocytogenes is valuable to track bacterial contamination throughout the FPE and in understanding persistence mechanisms, with limited studies from South Africa. Forty-six L. monocytogenes isolates from origins: Fish/seafood products (n = 32) (salmon, smoked trout, fresh hake, oysters), the FPE (n = 6), and clinical (n = 8) were included in this study. Lineage typing, antibiotic susceptibility testing, and screening for two genes (bcrABC and emrC) conferring sanitizer tolerance was conducted. The seafood and FPE isolates originated from seven different factories processing various seafood products with undetermined origin. All clinical isolates were categorized as lineage I, and seafood and FPE isolates were mostly categorized into lineage II (p < 0.01). Seafood and FPE isolates (53%) carried the bcrABC gene cassette and one fish isolate, the emrC gene. A subset, n = 24, was grouped into serotypes, sequence types (STs), and clonal complexes (CCs) with whole genome sequencing (WGS). Eight CCs and ten STs were identified. All clinical isolates belonged to serogroup 4b, hypervirulent CC1. CC121 was the most prevalent in isolates from food and the FPE. All isolates carried Listeria pathogenicity islands (LIPI) 1 and 2. LIPI-3 and LIPI-4 were found in certain isolates. We identified genetic determinants linked to enhanced survival in the FPE, including stress survival islets (SSI) and genes conferring tolerance to sanitizers. SSI-1 was found in 44% isolates from seafood and the FPE. SSI-2 was found in all the ST121 seafood isolates. Isolates (42%) harbored transposon Tn1688_qac (ermC), conferring tolerance to quaternary ammonium compounds. Five plasmids were identified in 13 isolates from seafood and the FPE. This is the first One Health study reporting on L. monocytogenes genetic diversity, virulence and resistance profiles from various types of seafood and its FPE in South Africa.

The objective of this study was to evaluate the efficacy of gamma irradiation, applied to different cheese sample sizes (250g and 500 g), against Listeria monocytogenes, Escherichia coli, coliforms and aerobic colony counts. The effects on cheese physicochemical and odour properties and all costs involved for the treatment were quantified. The Cobalt-60 γ-irradiator was used at a maximum dose of 5.0 kGy. The values for cheese moisture (28.6%), ash (3.78%), pH (5.1), protein (29.6%), fat (30.7%), salt (1.95%) and water activity (0.92%) were within the acceptable ranges for hard cheese after gamma irradiation treatment. The colour (yellowness, redness, chroma and hue angle) and texture (cohesiveness and springiness) values decreased (p < 0.05) with the treatment. Compounds such as safrole, acetylpyrazine, thiophene, 3,5-octadien-2-one and 1-Octen-3-one were present after the treatment, regardless of sample size. The gamma irradiation treatment resulted in 100%, 87.2%, 85.1% and 77.3% reduction in L. monocytogenes, coliforms, E. coli and aerobic colony counts, respectively. The study highlighted the efficacy of irradiation treatment and its affordability for resource-limited producers.

There have been numerous studies highlighting the efficacy of various bacteriophages (phages) and phage cocktails in the reduction of pathogens in food. Despite approval from legislative bodies permitting phage use in food processing environments, applied via spray or dip, there is still no information on which spray parameters should be used for successful implementation. The study here investigates phage survival diluted to 1% in distilled water (dH2O) and prepared bottled water (PBW), followed by a subsequent spray application through a fixed nozzle (530 μm) and strainer size (74 × 74 μm), with pressures of 3, 5, and 6 Bar. The survival of the phage was determined through sampling the outputs of the spray system and performing double agar overlay plaque assays. PBW decreased the phage concentration (p = 0.18) more than the dH2O (p = 0.73) prior to spray application. It was found that the PBW phage solution was less affected by the various spray parameters (p = 0.045) than the dH2O (p = 0.011). The study showed that unchlorinated water (dH2O), as well as a pressure of 3 Bar, had the highest output phage concentration through the nozzle and strainer, providing valuable information for industrial implementation.

Meat contamination by microorganisms could occur during numerous processes linked to game meat animal slaughter. These contaminants could pose a risk to product quality and consumer health. Contamination often occurs around the wound caused by shooting. Animal slaughter plants are given a responsibility to identify, evaluate and control the occurrence of hazards in their processing plant. To improve this control plan, the effectiveness of lactic (LA) and acetic acids (AA) for reducing the microbiological load directly around the wound was investigated. After killing by means of an aerial (helicopter) shotgun (n = 12) firing lead pellets and land-based rifle bullet shots (n = 36), samples of the flesh directly around the wounds of impala (Aepyceros melampus) were taken immediately after dressing (AD) before any treatment was conducted. Thereafter, at the step where carcasses are typically washed with potable water, the flesh directly around the wound was subjected to a wash with either ≈5 mL potable water (T1), 5% LA solution (T2) or 5% AA solution (T3) and then chilled overnight. Samples of the flesh directly around the wounds were also taken after chilling (AC). The aim of the study was to determine the effectiveness of each organic acid in reducing the microbiological load (total plate count; E. coli; coliforms and Salmonella) present in the flesh directly around the wounds of impala carcasses. The study found that shotgun pellets caused less body damage with fewer microorganisms recorded compared to samples from rifle-killed carcasses. LA reduced the occurrence of Salmonella during slaughter. The results of the other microorganisms revealed inconclusive outcomes on whether the application of water, 5% LA or 5% AA was effective in the reduction of the microbial organisms on the flesh directly around the wounds.

The quality of hot-deboned (within 90 min post-mortem; left leg) and cold-deboned (<4 °C, 24 h post-mortem; right leg) muscles of 15 ostriches were evaluated. The fan fillet, rump, big drum, moon, and triangle steaks were used to establish quality characteristics. Hot-deboning had no effect on the quality parameters; differences amongst muscles were found. The varying pHu values between muscles were still within the expected range for ostrich meat with the big drum having the highest pHu linking with its low drip loss percentage. The fan fillet had a redder (a*), more saturated (Chroma) colour, whereas the big drum was more blue (b*), with a corresponding lower hue angle. The fan fillet was the most tender (35.34 N ± 8.26) in contrast with the moon steak (72.23 N ± 15.81) which can be linked to the latter's high cooking loss. Hot-deboning which provides several economic advantages for the South African ostrich industry can be considered.

Although limited, studies have found conflicting results on whether co-grazing results in significant antibiotic resistance transfer between species. This type of farming system can act as a vector in the geographical spread of antibiotic-resistant bacteria in the environment. The aim of this study was to determine the antibiotic-resistant patterns between co-grazing and non-co-grazing livestock and wildlife species in South Africa. Escherichia coli was isolated from the faeces of various wildlife and livestock species from two farms in South Africa and was tested for antibiotic resistance using the Kirby–Bauer disk diffusion method against chloramphenicol, nalidixic acid, ampicillin, streptomycin, sulphafurazole, and tetracycline. A selection of some common antibiotic-resistant genes (blaCMY, aadA1, sul1, sul2, tetA, and tetB) were detected using PCR. The E. coli isolates from wildlife and livestock that co-grazed showed no significant differences in antibiotic resistance patterns. However, this was not the case for tetracycline resistance as the livestock isolates were significantly more resistant than the co-grazing wildlife isolates. The E. coli isolates from the non-co-grazing livestock and wildlife had significant differences in their antibiotic susceptibility patterns; the wildlife E. coli isolates were significantly more resistant to sulphafurazole and streptomycin than the livestock isolates, whilst those isolated from the cattle were significantly more resistant to ampicillin than the wildlife and sheep isolates. The results of this study suggest that there could be an exchange of antibiotic-resistant bacteria and genes between livestock and wildlife that co-graze.

The control of Salmonella in chicken processing plants is an ongoing challenge for many factories around the globe, especially with the increasing demand for poultry escalating processing throughputs. Foodborne outbreaks due to Salmonella still pose a prominent risk to public health. As chicken meat is a good reservoir for Salmonella, it is important for chicken processing plants to continuously optimize methods to reduce the incidence of Salmonella on their products. Current methods include the use of chemical antimicrobials such as chlorine-containing compounds and organic acids. However, these current methods are decreasing in popularity due to the rising rate of Salmonella resistance, coupled with the challenge of preserving the sensory properties of the meat, along with the increasing stringency of antimicrobial use. Bacteriophages are becoming more appealing to integrate into the large-scale hurdle concept. A few factors need to be considered for successful implementation, such as legislation, and application volumes and concentrations. Overall, bacteriophages show great potential because of their host specificity, guaranteeing an alternative outcome to the selective pressure for resistant traits placed by chemicals on whole microbial communities.

This study determined the antibiotic resistance patterns of Escherichia coli and Staphylococcus aureus from the raw meat and feces of three game species from three different farms across South Africa. The Kirby-Bauer disk diffusion method was used according to the Clinical and Laboratory Standards Institute 2018 guidelines. E. coli was tested against ampicillin, ceftazidime, chloramphenicol, streptomycin, sulphafurazole and tetracycline. S. aureus was tested against tetracycline, erthromycin, vancomycin, penicillin, oxacillin and cefoxitin. There were no significant differences in the E. coli antibiotic resistance profiles between the meat and fecal samples (except towards ceftazidime where 5% of the meat isolates were resistant and 0% of the fecal isolates). The S. aureus meat isolates showed high (75%) resistance towards penicillin and on average, 13% were resistant to oxacillin/ cefoxitin, indicating methicillin resistance. The results from this study indicate that there is incidence of antibiotic resistant bacteria from the feces and meat of wildlife species across South Africa, suggesting that cross contamination of the meat occurred during slaughter by antibiotic resistant bacteria from the abattoir personnel or equipment and or from carcass fecal matter. In addition, the results highlight the importance of food safety and hygiene procedures during slaughter to prevent cross-contamination of antibiotic resistant bacteria, as well as pathogens, onto raw meat.

Beef patties were treated with 450 μg/g of extracts from grape (Vitis vinifera) seeds (GSE), pomace (GPE) or orange (Citrus reticulata) pomace (OPE) and compared to negative (no extract; CTR) and positive (sodium metabisulphite; SMB) controls for their effect on colour, lipid and protein oxidation and bacterial growth under simulated retail display conditions (4 °C) for 9 d, and sensory quality. Antioxidant activity and redness of beef patties increased in the order of CTR < OPE = GPE < GSE < SMB. The order of thiobarbituric acid reactive substances and carbonyl values were CTR > GPE = OPE > GSE > SBM, while that of bacterial counts were CTR > GSE = GPE > OPE > SMB. Retail display period had significant effect on all the shelf-life parameters. Overall, intensity of aroma, beef-like aroma and flavour in beef patties were highest in OPE. Results suggested that GSE and OPE could be commercially valorised as natural antioxidants and antibacterials in beef patties, respectively.

M43 Evaluation of the effects of gamma irradiation treatment on the compositional, textural, color, volatile profile, and microbiological quality of an artisanal hard-pressed cheese. F. Nyamakwere1, G. Esposito2,1, K. Dzama1, P. Gouws1, T. Rapisarda3, G. Belvedere3, and E. Raffrenato*2,1, 1Stellenbosch University, Stellenbosch, South Africa, 2RUM&N Consulting, Reggio Emilia, Italy, 3Consorzio per la Ricerca nel settore della Filiera Lattiero-Casearia e dell’agroalimentare, Ragusa, Italy.

In contrast to other game species and domestic livestock, there is a paucity of evidence concerning yields and thus meat obtained from the African savanna buffalo (Syncerus caffer caffer ). The aim of our study was to investigate the effects of age (categorized) and sex on buffalo carcass yields. Towards this goal, male (n = 17) and female (n = 13), and adult (n = 23) and subadult (n = 7) buffaloes were slaughtered, and the weight of the carcass and various organs/offal and six major muscles [(biceps femoris (BF), semimembranosus (SM), semitendinosus (ST), longissimus thoracis et lumborum (LTL), infraspinatus (IS) and supraspinatus (SS)] determined. Buffaloes had a high dressing percentage, calculated from the warm carcass weight, and with the heaviest muscle weights measured for the BF, SM and LTL muscles. Adults had heavier muscle weights than subadults, and all parameters except the heart and IS muscle weight differed significantly between these age groups. In addition, the skin and head weight differed significantly between males and females. In summary, African savanna buffalo yields (∼58%) compared favourably to other domestic animals, with the heavy weight of valuable muscles suggesting their commercial potential as a high-end value-added product.

The shelf-life of beef was compared from 7-months old Angus steers (281 ± 15.4 kg initial body weight) fed 150 g/kg DM dried citrus pulp (DCP) or grape pomace (DGP) for 90 days. The antioxidant activity, bacterial load, and lipid and protein oxidation were evaluated on the longissimus lumborum subjected to air-permeable packaging at days 1, 3, 5, 7 and 9 post-slaughter. Beef antioxidant activity was DGP > DCP > control (P ≤ 0.05). Beef from steers fed DGP or DCP had higher L* values (P ≤ 0.05) and fewer (P ≤ 0.05) coliform counts than steers fed the control diet. Beef antioxidant activity was DGP > DCP > control (P ≤ 0.05). Beef TBARS and carbonyl contents were DGP < DCP < control (P ≤ 0.05). Overall, antioxidant activity decreased (P ≤ 0.05), while bacterial loads, TBARS and carbonyl contents increased (P ≤ 0.05) during retail display for all diets. Current findings indicate that DGP could be a better natural preservative than DCP when included in beef cattle finishing diets.

ABSTRACT Listeria monocytogenes is a ubiquitous, intracellular foodborne pathogen that is responsible for invasive listeriosis. The ability of L. monocytogenes to cause disease has some correlation with the serotypes of a specific lineage group, making the identification of lineage groups important for epidemiological analysis. The development of typing methods to link the strains of L. monocytogenes to an outbreak of listeriosis would help minimize the spread of the disease. The aim of this study was to design a PCR-restriction fragment length polymorphism (RFLP) method to differentiate between the lineage groups of L. monocytogenes. PCR-amplified fragments of the hly gene for 12 serotypes of L. monocytogenes were sequenced, aligned, and analyzed with the BioEdit program, and single nucleotide polymorphisms (SNPs) within regions of this gene were identified. Because of the difficulty in acquiring a serotype 4ab reference strain, this serotype was not included in this study. We tested the specificity and accuracy of the PCR-RFLP method on these L. monocytogenes reference strains and validated the method with 172 L. monocytogenes strains recovered from humans, food, and the food processing environment in 2000 to 2002 and 2008 to 2010 from regions within South Africa. PCR-RFLP analysis applied in this study placed L. monocytogenes serotypes into one of three lineage groups based on the sequence differences and SNPs within each lineage group. The SNPs were conserved in a region where RFLP analysis could be applied for a distinction between L. monocytogenes lineage groups. HIGHLIGHTS

Studies have shown that antibiotic resistance among wild animals is becoming a public health concern, owing to increased contact and co-habitation with domestic animals that, in turn, results in increased human contact, indirectly and directly. This type of farming practice intensifies the likelihood of antibiotic resistant traits in microorganisms transferring between ecosystems which are linked via various transfer vectors, such as rivers and birds. This study aimed to determine whether the practice of wildlife supplementary feeding could have an influence on the antibiotic resistance of the bacteria harboured by the supplementary fed wildlife, and thus play a potential role in the dissemination of antibiotic resistance throughout nature. Escherichia coli and Enterococcus were isolated from the faeces of various wildlife species from seven different farms across South Africa. The Kirby-Bauer disk diffusion method was used according to the Clinical and Laboratory Standards Institute 2018 guidelines. The E. coli (F: 57%; N = 75% susceptible) and Enterococcus (F: 67%; N = 78% susceptible) isolates from the supplementary fed (F) wildlife were in general, found to be more frequently resistant to the selection of antibiotics than from those which were not supplementary fed (N), particularly towards tetracycline (E.coli F: 56%; N: 71% / Enterococcus F: 53%; N: 89% susceptible), ampicillin (F: 82%; N = 95% susceptible) and sulphafurazole (F: 68%; N = 98% susceptible). Interestingly, high resistance towards streptomycin was observed in the bacteria from both the supplementary fed (7% susceptible) and non-supplementary fed (6% susceptible) wildlife isolates. No resistance was found towards chloramphenicol and ceftazidime.

Cloacal swabs were obtained from live ostriches reared on 30 different farms situated in South Africa (Oudtshoorn) during the period of June 2018 to July 2019 to determine the prevalence of Campylobacter and Arcobacter species. PCR (n = 168 pooled cloacal swabs), the Cape Town protocol (n = 836 cloacal swabs), International Organization for Standardization ISO 10272-1:2006 (n = 836 cloacal swabs), and a selective Arcobacter spp. method (n = 415 cloacal swabs) were used for detection. PCR determined an average prevalence of 24.63% for species belonging to the Campylobacteraceae family. The ISO 10272-1:2006 method determined a Campylobacter spp. prevalence level of 16.83%, while the Cape Town protocol could not detect Campylobacter spp. For Arcobacter spp., a prevalence of 18.80 and 39.14% was determined with the Cape Town protocol and the selective Arcobacter spp. method, respectively. Results showed that prevalence levels could be influenced by season, the source of water, and the presence of wild water birds. Higher prevalence levels for Campylobacter spp. (23.38%) and Arcobacter spp. (68%) were detected in ostriches sampled during spring and autumn, respectively. Higher prevalence levels for Campylobacter spp. (25.23%) and Arcobacter spp. (44.50%) were detected in ostriches reared on farms that made use of borehole water. Higher prevalence levels for Arcobacter spp. (44.38%) were seen in ostriches reared on farms with wild water birds. This research shows that ostriches from South Africa can be considered as potential carriers of species belonging to the Campylobacteraceae family.

The study evaluated shelf-life and sensory quality of meat from lambs fed finisher diets containing increasing levels of grape pomace (GP; 0, 5, 10, 15 and 20% GP/kg DM). Color, antioxidant activity and lipid oxidation of the longissimus lumborum were evaluated on different storage times (days 1, 3, 5, 7 and 9) post-slaughter using overwrapped air-permeable packaging. Treatments 0, 10 and 20% GP/kg DM were used for evaluation of protein oxidation and microbial counts on days 1, 5 and 7, while a trained panel assessed the sensory quality on day 1. Diet neither influenced meat color nor sensory quality. Diet × day interactions were observed for antioxidant activity, lipid and protein oxidation. Overall, the 20% GP/kg-diet finished lamb meat had the highest antioxidant activity and the lowest total viable bacterial counts, lipid and protein oxidation values during the shelf-life period. The 20% GP/kg DM in lamb diets, therefore, improved lamb meat shelf-life without negatively affecting sensory quality.

The drive towards sustainable food systems coupled with increased consumer sophistication have prompted innovation in waste valorization. Grape and citrus processing by-products, abundant in the Mediterranean and tropical regions, respectively, are expanding and are sustainable sources of bioactive phytochemicals that can be used as natural preservatives for foods. Phytochemical composition, antioxidant, and antimicrobial properties of extracts from grape pomace (GPE), seeds (GSE), and clementine mandarin peel and pulp (MPE) grown in South Africa were analyzed. Total phenols and carotenoids were highest in GPE followed by GSE and MPE (p ≤ 0.05). Flavonoids and anthocyanins were higher (p ≤ 0.05) in GPE and GSE compared to MPE. The GSE had the highest proanthocyanidins content followed by GPE and MPE (p ≤ 0.05). Ascorbic acid was only detected in MPE, which also had the highest titratable acidity and lowest pH values (p ≤ 0.05). The GSE had the highest antioxidant potency composite index followed by GPE and MPE (p ≤ 0.05). The order of antimicrobial activity of the extracts was MPE > GSE > GPE (p ≤ 0.05). Current findings show that GSE is a potential antioxidant while MPE holds promise as an antimicrobial for the food industry.