clinical, pathological, and molecular investigation and isolation of mycoplasma pulmonis in a laboratory animal production and breeding colonies with murine respiratory mycoplasmosis

This study investigated the prevalence of mycoplasma pulmonis (m. pulmonis) contamination and disease within  a 6 month period in a laboratory animal production center housing rats, mice, hamsters, guinea pigs, and rabbits. a total of 66 samples from different breeding colonies were subjected to culture, molecular diagnosis (pcr), and pathological examination. sampling of the involved organs was performed in animals showed clinical signs. clinical symptoms including tilt head and turning towards the affected ear, ruffled coat, chromodacryorrhea, and cobblestone lung, were observed in four adult rats. pcr revealed m. pulmonis dna in 33 samples (50%), indicating widespread contamination. however, positive cultures and isolation were confirmed in only 12 samples (18% of total samples), all originating from rat colonies. pathological changes such as atelectasis and bronchiectasis were observed in the samples of rats. the facility utilized a conventional breeding system with a shared air conditioner and also lacked biosecurity barriers, facilitating easy transmission of infection from infected rat to other animals. due to the lack of sensitivity of those animals to this microorganism, no apparent issues exhibited in them, suggesting the absence of stressful and predisposing conditions for opportunistic infections such as m. pulmonis. although microbial monitoring should be done regularly and periodically for various infectious agents.