Epidemiological investigation of an animal house based upon phage-typing and biotyping of Staphylococcus epidermidis

The value of biotyping and phage-typing coagulase-negative staphylococci in the epidemiological investigation of a laboratory animal house was clearly demonstrated. In the animal rooms in which conventional bacteriological methods revealed equal bacterial contamination between a conventional unit and one housing specified-pathogen-free rodents, biotyping identified Staphylococcus cohnii as the only species in the latter, compared to S. warneri, S. hominis, S. saprophyticus. S. xylosus abd S. epidermidis as well as S. cohnii in the conventional unit. Similarly, phagetyping revealed 2 phage types in the specified-pathogen-free compared to 7 in the conventional unit. Thus biotyping and phage-typing provided evidence for the existence of a barrier between these units that had presented similar gross bacteriological findings.