Effect of temperature on survival of Bacteroides fragilis subsp. fragilis and Escherichia coli in pus.

Approximately 40 to 60% of Bacteroides fragilis subsp. fragilis in pus from experimental intra-abdominal abscesses lost their viability within 24 h when stored at refrigeration temperature (4 degrees C) either aerobically or anaerobically. No viability loss of B. fragilis was noted when pus was stored at 25 degrees C. Only slight loss of viaability of B. fragilis was observed at 15 degrees C. Escherichia coli coexisting in pus with B. fragilis increased several 100fold in 24 h when stored at 25 degrees C, but no significant growth occurred when they were kept at 15 degrees C. Approximately 20 to 40% of E. coli lost their viability when such pus was stored at 4 degrees C. We suggest that 15 degrees C may be an alternative temperature for storage of anaerobic specimens in laboratories where some delay in routine processing is unavoidable.