Sample collection
A total of 460 samples were randomly been recovered from pneumonic (n =210) and apparently healthy (n =250) lungs of imported one humped camels during February to April 2018. The animals were submitted for routine slaughter. For the purpose of this study‘ pneumonic lungs’ was referred to those lungs that had gross lesions such as consolidation, fibrin deposition on the pleura, pleurisy, and/or adhesion; while ‘apparently healthy lungs’ was used to describe those without any gross lesions. Specimens were obtained aseptically while taking precautions to prevent surface contamination. Following collection, the samples were transported to the microbiology laboratory in special ice-filled containers within 2 h of sampling. Primary isolation of mycoplasmas from lung samples was performed in liquid medium using pleuropneumonia-like organism broth and agar media (PPLO; Difco, Fisher Scientific, Waltham, MA, USA). Purified isolates were maintained on PPLO agar media. Preliminary identification of the isolates was performed based on colony morphology as examined under stereo-microscope (Leitz, Germany), to scan the surface of the medium to visualize the colonies. Digitonin sensitivity test was carried out to differentiate between Mycoplasma  and Acholeplasma  genera using filter paper discs impregnated with 0.2 mL of 1.5% (W/V) ethanol solution of digitonin and dried overnight. Mycoplasma  spp. show digitonin sensitivity while Acholeplasma  spp. are resistant (Freundt et al., 1973). Biochemical identification was used for further testing of Mycoplasma  spp. Glucose fermentation, arginine deamination and urea hydrolysis tests were performed as described previously (Erno and Stipkovits, 1973; Howard et al., 1994). Serological confirmation of Mycoplasma spp. was additionally conducted as described by Clyde (1964), while the species-specific identification was performed with anti-M. bovis  hyperimmune serum (Lauerman et al., 1994) by the growth inhibition test utilizing dried antiserum impregnated paper discs. Standard antisera were used as control,M. bovis PG45, M. bovirhinis PG43 and M. argininiG230. Final identification of the isolates was achieved by PCR.