Survival of Staphylococcus aureus in intraperitoneal abscesses

An examination of 10 strains of Staphylococcus aureus for survival within abscesses developing in the peritoneal cavity of mice revealed three distinct patterns of survival. Although non-haemolytic mutants were destroyed more rapidly than were their parent strains, this difference could not be attributed to any particular haemolysin. In abscesses generated with mixtures of non-haemolytic variants and their parent strains, the former were preferentially eliminated; this suggests that the non-haemolytic variants were inherently more sensitive to the conditions within these lesions. Subsequent studies confirmed that abscess homogenates were cidal for staphylococci and that this activity resided in the insoluble fraction of the homogenates. Staphylococci added to abscess homogenates were killed, but only after a lag. This lag could be shortened or eliminated by incubating homogenates before adding the test organism. After development of a suitable assay, it was found that the cidal activity in abscess homogenates could be increased 3-20-fold by pre-incubation. Staphylococcal strains differed in their relative sensitivities to the cidal material; those strains rapidly destroyed within abscesses were the most sensitive and strains capable of better survival were more resistant. The results support the concept that the cidal material is responsible for destruction of staphylococci within such lesions.