Background and Aim: Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are the most significant pathogens of avian mycoplasmosis. This study aimed to isolate and identify MG and MS from chickens and detect the various virulence genes in the isolates. Moreover, the efficacies of different antibiotics were tested to identify suitable treatment regimens. Materials and Methods: We isolated MG and MS from 487 chicken samples of different ages located in different Governorates in Egypt using conventional isolation methods. The isolates were characterized by polymerase chain reaction (PCR) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and then tested for antibiotic sensitivity by the minimum inhibitory concentration (MIC) method. Results: The prevalence of MG among the isolates was 9.85%, with the highest percentage isolated from air sacs, while the prevalence of MS among the isolates was 1.6%. Moreover, the highest levels of the prevalence of both MG and MS were during the winter and autumn sampling, while the lowest levels were in the summer and spring. Following the 16S rRNA-based detection of Mycoplasma isolates, 14 MG and 5 MS isolates were identified by different PCR-based detection methods for various virulence genes. Nine MG isolates contain the mgc2 gene, six MG isolates contain the gapA gene, and three MS isolates contain the vlhA gene. We validated a duplex PCR method for the simultaneous identification of MG and MS, based on 100% of the MG and MS isolates generating common bands at 55 and 17 kDa, respectively. The MIC method identified tiamulin and spiramycin as the antibiotics of choice for the treatment of MG and MS infections, respectively. Conclusion: For more precise diagnosis of Mycoplasma infections in chicken flocks, conventional isolation methods must be confirmed by PCR. SDS-PAGE analysis helps in epidemiological studies and vaccine preparation. The MIC method can be used to help develop therapies to control avian mycoplasmosis infections.

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Aims This study was designed to investigate, in an in vivo setting, the effects of single and combined infections with either Mycoplasma gallisepticum (MG) and/or Escherichia coli on the chicken immune response induced by Newcastle disease virus (NDV) vaccine. Methods and Results Humoral immunity was measured through detection of NDV antibody and anti‐NDV IgG titres using haemagglutination‐inhibition test and enzyme‐linked immunosorbent assay, respectively. In addition, the expression levels of pro‐inflammatory cytokines' genes (interleukin (IL) 6, IL4 and interferon (IFN) γ) were analysed using quantitative reverse transcription PCR. Significant (P < 0·05) results in all immunological parameters were detected in the vaccinated noninfected chicken group in comparison with those in groups exposed to bacterial infections. Bacterial infection along with vaccination hampered the NDV antibodies production and reduced the vaccine upregulated cytokine genes. The vaccinated mixed infection group reported lower antibody titres and cytokines expression levels compared to those in the single infection groups. All the previously enhanced immunological parameters reflected the maximum protection post challenge with velogenic viscerotropic NDV in the vaccinated noninfected chicken group. Conclusions These findings provide novel insights into the immunosuppression activities of MG and E. coli infection in chickens vaccinated against NDV. Significance and Impact of the Study This study hopes to provide a better insight to the immunosuppressive action of bacterial pathogens in chickens. This will help to improve biosecurity strategies during NDV vaccination in the future.

Mycoplasma bovis (M. bovis) is one of the most significant bacteria, which leads to multiple bovine diseases such as keratoconjunctivitis, otitis media, arthritis, genital disorders, mastitis, and pneumonia in cattle. M. bovis is considered the second most pathogenic mycoplasmas infection after Mycoplasma mycoides sub sp. mycoides (Mmm) that causes contagious bovine pleuropneumonia. M. bovis is a wall-less host-specific bacterium. Currently, it is responsible for important economic problems worldwide such as reducing production, premature culling, and increasing the mortality of the affected animals. The infection caused by M. bovis is hampered due to the lack of effective vaccines and treatment. Besides, antibiotic resistance to macrolides and fluoroquinolones, the drug of choice for M. bovis treatment, has formidable economic losses due to treatment limitations by these antimicrobials. Our review highlights and discusses the taxonomy, general characteristics, economic importance, isolation, identification, and pathogenesis of M. bovis. Finally, it focused on the antimicrobial resistance of this particular bacterium.