Clinical usefulness of susceptibility testing of anaerobes.

We have studied the clinical usefulness of antibiotic susceptibility testing of fresh clinical isolates of anaerobes (primarily from blood cultures). Analysis of 65 patients showed that susceptibility reports were used in only 13 instances (20%), representing mainly orothopedic and CNS infections. Of the 47 patients whose susceptibilities were not used, 20 received therapy (appropriate in each case) based on the culture report, and 27 were treated empirically. Only six patients in the empirically treated group received inappropriate treatment, but four of those six died, and patients in this group as a whole had a worse outcome than did patients in the other groups. However, these empirically treated patients also had a somewhat worse prognosis. We suggest that susceptibility testing of anaerobes be reserved for bacteremic patients and for managing severe, chronic anaerobic infections, such as septic arthritis, osteomyelitis, and brain abscesses.