Bacteriological examination of a modern animal house containing small laboratory animals.

Floors and other areas totalling 1800 m2, comprising conventional and specified-pathogen-free (SPF) units, were screened bacteriologically 6 times in a year. The contamination indices observed were lower within than outside the units, and lower in the SPF than in the conventional unit. Bacterial counts in rooms containing animals in the conventional and SPF units were very similar. In all of the areas investigated within the units, most of the samples revealed less than 2 colony forming units per cm2. In contrast, high degrees of bacteriological contamination were detected in the changing rooms after showering or washing before entry. Staphylococcus epidermidis was the dominant bacterial species isolated. The bacteriological spectrum did not vary between the areas surveyed.