Long-term survival of Bordetella bronchiseptica in lakewater and in buffered saline without added nutrients.

Bordetella bronchiseptica grew from small inocula, and retained viability for at least 24 weeks, in unsupplemented lakewater or phosphate-buffered saline. From washed inocula of around 10(3) colony-forming units/ml, there was growth at both 10 degrees C and 37 degrees C to give 10(6)-10(7) colony-forming units/ml. At 10 degrees C, these counts were maintained with little diminution up to week 24 when observations ceased. In the tests at 37 degrees C, two of three strains tested showed similar retention of viability. These results suggest that B. bronchiseptica may exist as hitherto unsuspected reservoirs of infection in freshwater habitats.