Yersinia enterocolitica infections impose a significant public health and socioeconomic burden on human population in many countries. The current study investigated the prevalence, antimicrobial resistance profile and molecular diversity of Y. enterocolitica in meat and meat products across various retail outlets in selected provinces of South Africa (SA). In a cross-sectional study, a total of 581 retail meat and meat products were collected from four cities across three provinces of SA. Samples were from beef and pork products, which included 292 raw intact, 167 raw processed, and 122 ready-to-eat (RTE) meats. Samples were analysed using classical microbiological methods for isolation, identification and biotyping of Y. enterocolitica. Conventional polymerase chain reaction (PCR) was performed for confirmation, serotyping, screening of virulence (n = 11) and antimicrobial resistance (n = 18) genes. Phenotypic antimicrobial resistance profiles were determined against 12 antibiotics discs, using disc diffusion method. The overall prevalence of 12% (70/581) was reported across all cities with contamination proportion reported in samples collected from raw intact 15% (43/292), followed by raw processed 11% (18/167) and RTE meats 7% (9/122). All positive isolates were of biotype 1A with 7% (5/70) belonging to bioserotype 1A/O:8. Most of the isolates harboured ymoA, ystB, fepD, ail, fepA, invA and myfA virulence genes. High antimicrobial resistance frequency was observed for ampicillin (94%), cephalothin (83%) and amoxicillin (41%), respectively. Of the 18 tested antimicrobial resistance genes, blaTEM was the most predominant (40%) followed by cmlA (21%). This study reveals the presence of antimicrobial resistant Y. enterocolitica possessing virulent genes of public health importance in products of animal origin, therefore, health monitoring and surveillance of this pathogen is required.

Salmonellosis remains one of the most frequently reported foodborne diseases globally, with the highest burden in low-resource areas. The millions of deaths caused by Nontyphoidal Salmonella (NTS) infections emphasize the urgent need for timely, detailed, and evidence-based interventions to effectively manage and monitor NTS burdens. This study retrospectively analyzed 1,028 NTS isolates from animals, the environment, and food products in South Africa, collected between 1960 and 2023. Among the 102 serotypes identified, S. Heidelberg, isolated only between 2000−2009 and 2020−2023, accounted for 94.3% of isolations during the latter period, suggesting a recent shift in Salmonella epidemiology in the region. The highest resistance rates were observed for cefoxitin (65.7%), cephalothin (62.8%), and tetracycline (59.8%), with a significant increase in resistance to several antibiotics, including ceftriaxone and aztreonam, from 2010−2023. Genetic analysis revealed that S. Gallinarium had the highest prevalence of antibiotic resistance genes, such as tetA (71.4%), qnrA (64.3%), cat1 (64.3%), bla_PSE (57.1%), and both bla_CMY-2 and qnrB at 50%. The bla_PSE and bla_SHV genes were strongly associated with ceftriaxone resistance in S. Dublin isolates, while bla_PSE and qnrS were linked to chloramphenicol resistance in S. Enteritidis and S. Dublin isolates. Additionally, 87% of the virulence genes screened were present in over 50% of the serotypes, indicating increased adaptability and potential shifts in disease dynamics. The rise in antimicrobial resistance, driven by antimicrobial misuse, horizontal gene transfer, and biofilm formation, could alter serotype dynamics and changing disease epidemiology. This trend underscores the urgent need for effective antimicrobial stewardship and surveillance to combat the spread of antibiotic resistance in Salmonella populations.

Actinobacillus pleuropneumoniae is a major bacterial pathogen causing porcine pleuropneumoniae, which is a disease of notable economic impact and high fatality rates among pigs worldwide. It has been reported that 19 distinct serotypes of this bacterium exist. Despite its global prominence, there exists a scarcity of information regarding its prevalence and distribution in South Africa. Thus, this study used laboratory records to investigate the serotype diversity, temporal distribution, and seasonal patterns of A. pleuropneumoniae isolated from porcine samples spanning from 1985 to 2023 within South Africa. Data from laboratory registries of 354 cases, obtained from three veterinary laboratories in South Africa, were analyzed. The data were categorized into two-time frames: term 1, covering 1985 to 2001, and term 2, spanning from 2002 to 2023. The dataset identified 11 different serotypes, with serotype 7 being the most prevalent at 22.7% (n = 62), which was followed by serotype 5 at 13.8% (n = 42). The study highlighted variations in the prevalence of serotypes among diseased animals over a 38-year period. Serotypes 3, 5, 7 and 8 were commonly observed during this time, while serotype 4 was absent from 1985 to 2001, and serotypes 1, 6, and 10 were absent from 2002 to 2023. The distribution of serotypes showed a diverse variation in the age of affected animals, clinical manifestation, and seasonal occurrence. Key findings revealed that serotype 7 was the most prevalent across all seasons with the highest occurrence in winter. Additionally, Gauteng province showed the highest prevalence of various serotypes. The information collected during this study will serve as a baseline for future epidemiological studies as well as inform control strategies.

Salmonella Typhimurium is a major cause of human and animal salmonellosis, impacting global socioeconomic factors. This study examined antibiotic resistance patterns, virulence genes and plasmids in S. Typhimurium isolates from nine South African provinces (1999–2021). Among 180 randomly selected isolates, 129 were confirmed as S. Typhimurium from animal (n = 94), food (n = 16), environment (n = 7) and feed (n = 12) sources using polymerase chain reaction (PCR). Phenotypic resistance was assessed against 13 antibiotics, revealing high resistance levels: 86.8% to ciprofloxacin, 69.0% to ceftriaxone and 65.1% to piperacillin. Multidrug resistance (up to 11 antibiotics) was observed. Genetic analysis identified resistance genes, including blaPSE (32.6%), blaCMY-2 (21.7%), tetA (24.0%), tetB (22.5%), qnrB (21.7%) and qnrA (20.2%). Class 1 integrons were found in 47.4% of isolates. Virulence genes were prevalent, including sopB (95.3%), sspH1 (82.9%), sifA (82.9%), pefA (79.8%), spvC (79.1%), sspH2 (77.5%), srgA (71.3%) and invA (100%). Plasmid analysis detected 2 kb, 8 kb and 90 kb plasmids, with the 90 kb plasmid being most common (71.3%). Enterobacterial Repetitive Intergenic Consensus (ERIC) PCR identified 44 clusters (A–RR), including 6 major clusters. Contribution: These findings highlight the urgent need for enhanced surveillance and intervention strategies to curb antibiotic resistance and virulence in S. Typhimurium populations in South Africa, stressing the importance of monitoring and control measures to address this public health threat.

Heartwater is an economically important disease of livestock and some wild ruminants in Southern Africa. The study used retrospective laboratory data from Lephalale Veterinary Laboratory, Limpopo to establish the prevalence and seasonal occurrence of heartwater in commercial farms of Lephalale Municipality between 2010 and 2022. A total of 472 brain samples from livestock (cattle, goats, sheep) and game carcasses brought to the laboratory for postmortem examination were subjected to heartwater testing using Giemsa staining technique. The overall prevalence of heartwater in Lephalale Municipality was 34.1% (95% CI = 29.9–38.6, p < 0.001). During the years under investigation, there was a significant (p < 0.001) variation, with the highest and lowest prevalence in 2022 (72.2%) and 2019 (6.3%), respectively. The prevalence of heartwater was high in springbok (57.1%), sheep (49.3%), cattle (36.6%) and goats (32.2%). Heartwater was detected throughout the year with autumn having the highest (40.6%) frequency followed by summer (40.3%), spring (30.5%) and winter (25.5%). This study is the first to establish the prevalence and seasonality of heartwater in Lephalale Municipality which will serve as a baseline for prevention and control strategies as well as future epidemiological studies. Official surveillance programmes, more research on the distribution and genotypes of E. ruminantium in the area need to be undertaken for better understanding of the disease in the area.

Brucellosis, a contagious zoonotic bacterial infection affecting livestock and wildlife, is primarily caused by Brucella abortus, globally. However, in South Africa, the true prevalence of bovine brucellosis remains unknown because of a lack of epidemiological data. Therefore, this study used diagnostic data to evaluate and determine the seropositivity of bovine brucellosis based on Rose Bengal test (RBT) screening and confirmation with complement fixation test (CFT) in Limpopo and Free State provinces between 2013 and 2022. The use and limitations of this data were also evaluated based on the bovine brucellosis scheme in South Africa. The study revealed the overall seropositivity of 4.2% (n = 8980/212 440) for bovine brucellosis based on RBT and CFT in series. In Limpopo province, the brucellosis seropositivity was slightly higher at 4.3% (n = 7488/173 011) compared to 3.8% (n = 1492/39 429) in Free State province. Analysis of brucellosis distribution over the study period indicated significant variation (p < 0.001) both between and within the provinces. Notably, the highest prevalence in Limpopo occurred during 2013–2017, whereas in Free State, peak prevalence was observed in 2013 and 2016. Challenges preventing an accurate reflection of the brucellosis seropositivity in these provinces for the period include a lack of data on vaccination history and herd status of the samples submitted, as well as the inability to match the CFT results from different laboratories, because some laboratories are only accredited to perform the RBT. Contribution: Insights gained from retrospective studies such as this study can play crucial roles in shaping effective control and preventative measures against bovine brucellosis. Given the challenges in obtaining confirmatory test results, we suggest that brucellosis tests be conducted at a single central laboratory or that the government provides a central database where all laboratories can enter their data. Furthermore, information submitted to the laboratories must make herd and vaccine history compulsory for sample submission to ensure more accurate data.