Abstract
1. The bacteriology of the pus from 79 cases of tropical pyomyositis has been studied. In 74 cases Staphylococcus aureus was isolated in pure culture.2. Phage typing showed that 60% of the pyomyositis strains belonged to phage Group II as compared with 22% for miscellaneous hospital infections and 21% for nasal carrier strains.3. A high proportion of the Group II strains from pyomyositis were found to be penicillin resistant and it is thought that this is unlikely to be due to the use of penicillin therapeutically but is probably a natural characteristic of the strains.4. Other suggested aetiological factors in pyomyositis such as leptospirosis and syphilis have been investigated but no association has been found.5. The phage types of staphylococci found in Uganda have been compared with those reported from England and Australia and found not to be strikingly different.