Comparison of Chalquest and Hayflick media, with and without ammonium reineckate, for isolating Mycoplasma pulmonis from rats.

Chalquest and Hayflick media with and without ammonium reineckate were compared for isolation of Mycoplasma pulmonis from the nasopharyngeal ducts, tracheobronchial trees, and middle ears of 66 naturally infected rats. The results show that 92% (366 of 396) of the samples were positive for M. pulmonis in Chalquest medium with and without ammonium reineckate and 66% (260 of 396) were positive in Hayflick medium with and without ammonium reineckate (P less than 0.001). An enhancing effect of ammonium reineckate on M. pulmonis isolation was observed only in Hayflick medium; the isolation rate was 76% (151 of 198) in Hayflick medium with ammonium reineckate as compared with 55% (109 of 198) in Hayflick medium without ammonium reineckate (P less than 0.03). No significant differences in isolation rates were observed between Chalquest medium with and without ammonium reineckate. The mean growth time of M. pulmonis on Chalquest medium was 3.4 days as compared with 5.1 days in Hayflick medium, indicating that M. pulmonis can be detected earlier on Chalquest medium than on Hayflick medium. These data indicate that Chalquest medium is superior to Hayflick medium for M. pulmonis isolation from rats.