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Background: The impact of chickens on maintaining the economy and livelihood of rural communities cannot be overemphasized. In recent years, mycoplasmosis has become one of the diseases that affect the success of South African chicken production. Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are the most prevalent strains of Mycoplasma in South Africa. MG and MS are significant respiratory pathogens affecting the productivity of chickens. The present study aimed to molecularly detect using qPCR and characterize the presence of MG and MS using phylogenetic analysis. The phylogenetic analysis was utilized to clarify general evolutionary relationships between related taxa of different MG and MS observed in tracheal swabs from South African chicken breeds., Methods: Forty-five tracheal swabs of the Lohmann Brown (n = 9), Rhode Island Red (n = 9), Ovambo (n = 9), Venda (n = 9), and Potchefstroom Koekoek (n = 9) breeds were collected from symptomatic chickens present in the commercial farm. To detect MG and MS, DNA was extracted from tracheal swabs and faecal samples, and qPCR was performed with a 16 s rRNA (310 bp) and vlhA (400 bp) gene fragment. Following the sequencing of all the amplicons, MG, and MS dendrograms showing the evolutionary relationships among the five South African chicken breeds and the GeneBank reference population were constructed., Results: The qPCR revealed the presence of MG and MS in 22% (2/9) of the tracheal swab samples tested for MS only in Rhode Island Red breeds; 66.6% (6/9) and 33% (3/9) of the tested samples in Ovambo breeds; and 11.1% (1/9) and 44.4% (4/9) of the tested samples in Venda breeds. No MG or MS were detected in the Lohmann Brown or Potchefstroom Koekoek breed. Furthermore, qPCR revealed the presence of MG in pooled faecal samples from Lohmann Brown and Ovambo breeds. Eight different bacterial isolates were recognized from both samples. Four isolates were of the 16 s ribosomal ribonucleic acid (rRNA) gene (named PT/MG51/ck/00, PT/MG48/ck/00, PT/MG41/ck/00 and PT/MG71/ck/00) gene of Mycoplasma gallisepticum, and the other was Mycoplasma Synoviae variable lipoprotein hemagglutinin A (vlhA) gene (named PT/MSA22/ck/01, PT/MS41/ck/01, PT/MS74/ck/01 and PT/MS46/ck/01) which were available in GenBank. These isolates were successfully sequenced with 95-100% similarity to the isolates from the gene bank., Conclusion: The study revealed the presence of both MG and MS in the chicken breeds sampled. Furthermore, the different breeds of chicken were found to be susceptible to infection under the intensive or commercial management system. Therefore, continuous surveillance is encouraged to prevent the spread and outbreak of MG and MS in the poultry industry in South Africa., (© 2024. The Author(s).)

Escherichia coli O157:H7 is a foodborne pathogen that has been linked to global disease outbreaks. These diseases include hemorrhagic colitis and hemolytic uremic syndrome. It is vital to know the features that make this strain pathogenic to understand the development of disease outbreaks. In the current study, a comparative genomic analysis was carried out to determine the presence of structural and functional features of O157:H7 strains obtained from 115 National Center for Biotechnology Information database. These strains of interest were analysed in the following programs: BLAST Ring Image Generator, PlasmidFinder, ResFinder, VirulenceFinder, IslandViewer 4 and PHASTER. Five strains (ECP19-198, ECP19-798, F7508, F8952, H2495) demonstrated a great homology with Sakai because of a few regions missing. Five resistant genes were identified, however, Macrolide-associated resistance gene mdf(A) was commonly found in all genomes. Majority of the strains (97%) were positive for 15 of the virulent genes (espA, espB, espF, espJ, gad, chuA, eae, iss, nleA, nleB, nleC, ompT, tccP, terC and tir). The plasmid analysis demonstrated that the IncF group was the most prevalent in the strains analysed. The prophage and genomic island analysis showed a distribution of bacteriophages and genomic islands respectively. The results indicated that structural and functional features of the many O157:H7 strains differ and may be a result of obtaining mobile genetic elements via horizontal gene transfer. Understanding the evolution of O157:H7 strains pathogenicity in terms of their structural and functional features will enable the development of detection and control of transmission strategies., (© 2023. The Author(s).)