Mycoplasma pulmonis and Mycoplasma arthritidis in rodents from animal houses

Abstract

Rats and mice from different animal house facilities without microbial barriers and one from barrier sustained facilities were checked for mycoplasma presence by lung perfusion with tracheobronquial lavage and ear flushing. Mycoplasmas were characterized by "fried egg" colonies, Dienes stain and digitonine resistance. Glucose catabolism, arginine hydrolysis, tetrazoliun reduction and film/ spots production was applied as screening differential assays. Identification was performed by growth inhibition test. In the barrier sustained colonies, mycoplasmas were not detected, but from a conventional animal house, M. pulmonis was found in the follow order: 20.0% in Swiss mice, 14.28% in C57BL/6J colonies and 83.79% in Wistar rats. M. arthritidis was isolated only from rats by ear flushing in order of 5.4%. Both species were observed in one rat and one unidentified strain of mycolplasma was isolated from hamsters. M. pulmonis was obtained from rats but not from mice proceeded from other two conventional animal houses. Mycoplasma infection rate could not be established in these facilities because rats and mice were specially selected, as usually is to search mycoplasmas, based on their origin and symptoms. The authors suggest that mycoplasma investigation nust be permanent in any animal house rearing rodents. Mycoplasma infection rate must be established with a representative sampling not including only sick animals.