Abstract
Mycoplasmas are considered as important avian pathogens, which cause a great economical loss in the poultry industry. As it responsible for both respiratory disease and synovitis in poultry. The aim of this study was to isolate and identify Mycoplasma gallisepticum and Mycoplasma synoviae from chickens and determine the efficacy of different antibiotics. Additionally, detection of some substantial virulence genes. Two hundred chicken samples were collected and cultured onto specific PPLO medium .The isolates were characterized by polymerase chain reaction then tested for antibiotic sensitivity by the minimum inhibitory concentration (MIC) method. The results reported that 15 samples (7.5%) were positive by culturing with prevalent of Mycoplasma synoviae and Mycoplasma gallisepticum with 12 (80%) and three (20%). Following the 16S rRNA-based detection of Mycoplasma isolates, 12 Mycoplasma synoviae and three Mycoplasma synoviae isolates were identified by different PCR-based detection methods for various virulence genes. Three Mycoplasma gallisepticum isolates contain the mgc2 gene, and nine Mycoplasma synoviae isolates were positive for the ISR (intergenic spacer region) gene. All isolates had lowest MIC values for Tylvasolin with a range of (0.062-0.125μg/mL) followed by Lincomycin, Tiamulin, Tilmicosin and Tylosin with a range of (0.062-1 μg/mL). However, the Mycoplasma synoviae isolates displayed variance in MICs for Oxytetracycline with a range of 0.5 to 8 μg/mL, and Chlorotetracycline with a range of 2 to 8 μg/mL. Meanwhile, high MIC values for Enrofloxacin were detected in all isolates with MICs ranging from 8 to 32 μg/mL. Furthermore, the MIC method identified Tylvasolin, Lincomycin, Tiamulin, Tilmicosin and Tylosin as the antibiotics of choice for the treatment of MS infections. In conclusion, these data may help in prevention and control of Mycoplasma infection in poultry.

Key words: M.gallisepticum, M. synoviae, antimicrobial, PCR, MIC, virulence genes.