Study of Bacterial Zoonoses in Conventional Sprague Dawley, Wistar and NMRI Rat Breeding Colonies

Bacterial zoonoses have the first priority in laboratory rat colonies to be considered, monitored and eradicated. These bacteria count as health risk factors for personnel and researchers and may interfere with experimental results. In this study, conventional laboratory rats from three breeding colonies including Salmo-nella typhimurium, Salmonella enteritidis, Streptobacillus moniliformis, Pasteurella pneumotropica and Strepto-coccus pneumonia, were screened for detection of five bacterial zoonoses. Study population were carried out for 60 rats of same numbers of male and female of the three breeds including, Sprague Dawley, Wistar and NMRI of 3-4, 6-8 and 25 weeks ages. Animals were allocated in a random fashion as 20 animals for each breed. Two hundred and forty specimens of nasopharynx (n = 120), cecum (n = 60) and liver (n = 60) were taken from all animals and cultured for bacteriological tests. Mentioned zoonotic bacteria were absent in all of specimens; however in 82.1% of the specimens, commonly nonpathogenic bacteria, mainly Escherichia coli, Bacillus spp, Streptococcus other than Streptobacil-lus moniliformis, and Entrobacter aerogenes were observed. There was significant difference in value of infec-tion to nonzoonotic bacteria only between first two age groups of animals with 25 weeks age group in three breed rats (P < 0.001). Results of our study recommend that use of these animals have no human risk or research interfe-rences for mentioned zoonotic bacteria.