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Among many avian mycoplasmas, Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) are recognized as the main etiological agents of respiratory diseases and infectious synovitis in chickens and turkeys causing tremendous economic losses worldwide. Therefore, proper treatment is promoted for the control of these diseases. This study was the first in Egypt to evaluate the in vitro efficacy of various antimicrobials against field MG and MS isolates recovered from chicken and turkey flocks using both conventional broth microdilution and quantitative real-time polymerase chain reaction assays. Totally, 47 mycoplasma isolates were recovered from 160 collected tracheal samples (29.4%). Of these, 44 MG (27.5%) and 3 MS (1.9%) were identified using conventional and molecular assays. The in vitro susceptibilities of 4 representative mycoplasma field isolates (3 MG and one MS) to 8 antibiotics and 4 essential oils were investigated. The tested isolates showed various susceptibilities to tested antimicrobials. Toldin CRD, followed by clove, cumin, and cinnamon oils were effective against both MG and MS clinical isolates with minimum inhibitory concentration (MIC) values ranging from 0.49 to 15.63 µg/mL. Similarly, tylvalosin was the most active antibiotic against MG and MS isolates with the lowest MIC values (0.015 to 0.03 µg/mL). DNA loads of both MG mgc2 and MS vlhA genes were markedly decreased upon treatment with majority of the tested antimicrobials confirming their effectiveness as was also evaluated by conventional MIC results. In conclusion, Toldin CRD and tylvalosin were found to be the most effective antimicrobials in this study. This finding highlights the importance of using these antimicrobials in controlling mycoplasma infections in chickens and turkeys., (© 2019 Poultry Science Association Inc.)

Mycoplasma synoviae (MS) is a common respiratory pathogen in the poultry industry. Eradication of MS from broiler breeder flocks is important for reducing economic losses caused by MS-associated diseases on broiler farms. An outbreak of MS infection was detected on a multi-age Korean broiler breeder farm that implements a flock replacement program every 3 to 6 months and uses A-type cages. Continuous administration of tilmicosin after 2 rounds of intensive antibiotics treatment with chlortetracycline, doxycycline, and enrofloxacin reduced MS shedding from the MS-positive flocks and eventually eradicated MS from the farm. Flock 3 was the last MS-positive flock by both PCR and enzyme-linked immunosorbent assay (ELISA), while flocks introduced to the farm after flock 3 were MS-negative by both PCR and ELISA at the time of depletion. This is the first report of successful eradication of MS from a multi-age broiler breeder farm using continuous antibiotic treatments., (© 2015 Poultry Science Association Inc.)