Antibiotic residue in meat is a serious public health concern due to its harmful effects on consumer health. This study aimed at estimating the residue levels of four commonly used antibiotics in meat samples using three analytical methods (ELISA, TLC and HPLC). A total of 150 samples of raw meat from sales points were analysed for ciprofloxacin, streptomycin, tetracycline, and sulphanilamide residues. Overall, ELISA analysis showed that 56, 34, 18, and 25.3% of the samples tested positive for ciprofloxacin, streptomycin, sulphanilamide and tetracycline residues respectively while TLC and HPLC detected 21.4, 29.4, 92.5, and 14.6%, and 8.3, 41.1, 88.8, and 14.6% of the samples as containing the residues, with ciprofloxacin and sulphanilamide having the lowest and highest occurrence, respectively. Furthermore, the concentrations of antibiotic residues were in the ranges of 19.8–92.8, 26.6–489.1, 14.2–1280.8, and 42.6–355.6 μg/kg with ELISA, while HPLC detected concentration ranges of 20.7–82.1, 41.8–320.8, 65.2–952.2 and 32.8–95.6 μg/kg for sulphanilamide, tetracycline, streptomycin, and ciprofloxacin, respectively. Mean ciprofloxacin and streptomycin residue levels were above the Codex/SA MRL recommended limit, while 3% of the samples contained multidrug residues. Although some of the mean residues levels were below the permissible limits, the co-occurrence of multidrug residues in some of the samples calls for concern.

Rodents cause serious adverse effects on farm production due to destruction of food, contamination of feed, and circulation of diseases. The extent of damage or the diseases spread will depend on the type of rodents that invade the farm. This study was conducted in order to find out the species of rodents that infest poultry farms around Mafikeng, North West Province of South Africa. The study was part of a broader project that was investigating Salmonella vectors in the poultry farms around the province. The study trapped 154 rodents from selected farms and used the Cytochrome oxidase subunit 1 (COI) and the Cytochrome b (Cyt-b) barcoding genes for species identification. Two rodent pest species, namely, Rattus rattus (the black rat) and Rattus tanezumi (the Asian Rat/Asian House Rat) were identified. A total of 99 (64.3%) were identified as Rattus rattus and 55 (35.7%) were Rattus tanezumi. Between the two target genes, Cyt-b gene was only able to identify 40 (25.97%) of the total samples while COI was more efficient and amplified all the samples and thus was a better target gene for this kind of identification. The two rat species identified are known vectors of serious diseases; thus their presence should be regarded as an indication of high risk for diseases. Despite having been detected in the country before, finding R. tanezumi as the second largest rat species in the area was unexpected since this species is known to be indigenous to Asia.

The widespread use of antibiotics for treatment of bacterial infections and growth promotion in the poultry industry has effectively increased antibiotic resistance around the world. Antibiotics resistance can be caused by different mechanisms and can be determined through phenotypic and molecular methods. The aim of the present study was to determine the occurrence of antibiotic resistance in Salmonella serovars isolated from layer chickens and rats in poultry houses. Phenotypic testing of antimicrobial resistance was performed using the Kirby-Bauer disc diffusion method. Furthermore, molecular evaluations and PCR assay were conducted for detecting resistance genes and class 1 integrons. A total of 144 Salmonella isolates (68 from rats and 46 from chickens) serovars were assessed. Evaluation of phenotypic resistance patterns demonstrated that Salmonella isolates have the highest antibiotic resistance for rifampicin (100%) followed by tetracycline (68%), ciprofloxacin (48%), sulphonamides (42%), chloramphenicol (39%), nalidixic acid (33%), ampicillin (28%), cephalothin (18%), streptomycin (18%), amoxicillin-clavulanic acid (6%), enrofloxacin (5%), and gentamicin (4%). Some Salmonella serovars revealed multi-drug resistance for up to four different antibiotics. According to PCR results, all the tested resistant gene markers (tet, cat, blaTEM, sul, qnrA, and aadA) were detected from the Salmonella isolates. The study further confirmed that 68% of Salmonella isolates were harboring class 1 integrons and the majority of the isolates (n=52) which were harboring these genes were recovered from the rats. The results of the present study provided that the Salmonella spp. isolated from chickens and rats in poultry houses, exhibited significant antibiotic resistance. Moreover, the current research ultimately highlights the importance of rats as carriers of antibiotic-resistant bacteria and the risk of transmission to chickens and humans. DECLARATIONSAuthor's contributions Ramatla T. performed the experiments and wrote the first draft. Moeti OT and Thekisoe OMM provided the analysis tools and data analysis and reviewed the manuscript. Michelo S conceived and designed the experiments, provided reagents, materials and approved the final paper. Consent to publishAll the authors agreed to publish the manuscript and declared that this work has not been previously published elsewhere.

One of the main global concerns is the usage and spread of antibiotic resistant Salmonella serovars. The animals, humans, and environmental components interact and contribute to the rapid emergence and spread of antimicrobial resistance, directly or indirectly. Therefore, this study aimed to determine antibiotic resistance (AR) profiles of Salmonella serotypes isolated from the environment, animals, and humans in South Africa by a systematic review and meta-analysis. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines were followed to search four databases for studies published from 1980 to 2021, that reported the antibiotic resistance profiles of Salmonella serotypes isolated in South Africa. The AR was screened from 2930 Salmonella serotypes which were isolated from 6842 samples. The Western Cape province had high pooled prevalence estimates (PPE) of Salmonella isolates with AR profiles followed by North West, Gauteng, and Eastern Cape with 94.3%, 75.4%, 59.4%, and 46.2%, respectively. The high PPE and heterogeneity were observed from environmental samples [69.6 (95% CI: 41.7−88.3), Q = 303.643, I2 = 98.353, Q-P = 0.045], animals [41.9 (95% CI: 18.5–69.5), Q = 637.355, I2 = 98.745, Q-P = 0.577], as well as animals/environment [95.9 (95% CI: 5.4−100), Q = 55.253, I2 = 96.380, Q-P = 0.300]. The majority of the salmonella isolates were resistant to sulphonamides (92.0%), enrofloxacin and erythromycin (89.3%), oxytetracycline (77.4%), imipenem (72.6%), tetracycline (67.4%), as well as trimethoprim (52.2%), among the environment, animals, and humans. The level of multidrug-resistance recorded for Salmonella isolates was 28.5% in this review. This study has highlighted the occurrence of AR by Salmonella isolates from animals, humans, and environmental samples in South Africa and this calls for a consolidated “One Health” approach for antimicrobial resistance epidemiological research, as well as the formulation of necessary intervention measures to prevent further spread.

This study aimed to identify ticks infesting dogs admitted to the Potchefstroom Animal Welfare Society (PAWS) and to detect tick-borne pathogens they are harbouring. A total of 592 ticks were collected from 61 stray dogs admitted to PAWS originating from several suburbs in and near Potchefstroom, South Africa. The dog ticks were identified as Haemaphysalis elliptica (39%) and Rhipicephalus sanguineus (61%) by both morphological and DNA analyses. Of these ticks, H. elliptica consisted of 67.5% (156/231) and 32.5% (75/231) female and male ticks, respectively, whilst R. sanguineus consisted of 48.5% (175/361) and 51.5% (186/361) female and male ticks, respectively. Microscopic examination of blood smears from engorged female ticks indicated overall occurrences of 0.5% (1/204) for Babesia spp. from R. sanguineus, 1% (2/204) of Anaplasma spp. from H. elliptica, and 22% (45/204) of Rickettsia spp. from both H. elliptica and R. sanguineus. Using pooled samples molecular detection of tick-borne pathogens indicated overall occurrences of 1% (1/104) for A. phagocytophilum in H. elliptica, 9.6% (10/104) of Rickettsia spp. in H. elliptica and R. sanguineus, 5.8% (6/104) of Ehrlichia canis in H. elliptica and R. sanguineus, and 13.5% (14/104) of Coxiella spp. in both H. elliptica and R. sanguineus. Additionally, PCR detected 6.5% (2/31) of Coxiella spp. DNA from H. elliptica eggs. Our data indicate that urban stray dogs admitted at PAWS are infested by H. elliptica and R. sanguineus ticks which are harbouring several pathogenic organisms known to cause tick-borne diseases.