Coinfection of laboratory rats with Mycoplasma pulmonis and Chlamydia pneumoniae.

Routine examinations of conventional outbred Wistar rats in our laboratory showed increased serum levels of alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, and urea. Electron microscopy and specific reactions showed C. pneumoniae and M. pulmonis in lung, liver, spleen, heart, and kidney sections. We could not exclude the fact that other infectious microorganisms detected through routine health surveillance affected the Wistar rat colony; however, we have not identified any of those microorganisms by electron microscopy of the organs listed. Natural coinfection of C. pneumoniae and M. pulmonis can occur in laboratory rats and is associated with histopathological and functional compromise of many organs. Further studies comparing different conventional animals and specific pathogen-free animals are necessary to better understand the present findings and to define whether coinfection influences the results of experimental studies with rats.