Limited Value of Routine Stool Cultures in Patients Receiving Antibiotic Therapy
American Journal of Clinical Pathology
A b s t r a c t In the laboratory investigation of suspected community acquired diarrhea, stool cultures may be ordered on patients receiving antibiotic therapy. Because many antibiotics cause profound changes in intestinal microbial flora, the value of these cultures is not known. To determine the effect of concurrent antibiotic therapy on results of routine stool cultures in the isolation of enteropathogens, a retrospective analysis of fecal cultures submitted during a 14-month period was
... onth period was performed. Of 930 specimens from 856 patients, there were 236 samples (25.4%) from 223 patients (26.1%) receiving antibiotics. Of these, 198 cultures (83.9%) from 186 patients (83.4%) receiving antibiotic therapy showed no growth on all media or growth of only gram-positive organisms. None of these specimens revealed enteropathogens. The results of this study demonstrate that there is little value in culturing of stools of patients receiving antibiotics. Significant cost savings can be realized by elimination of these cultures. Stool cultures are performed routinely to isolate common enteropathogens in the laboratory investigation of community-acquired diarrhea. Based on the results of several studies, cost-effective guidelines have been proposed to maximize the rate of positive fecal cultures. These guidelines include the following: (1) elimination of routine cultures in patients who experience the onset of diarrhea 3 days or more after admission to the hospital, 1-6 (2) submission of a single rather than multiple specimens, 1,5,6 and (3) elimination of smears of rectal swabs and whole stool specimens for detection of polymorphonuclear leukocytes.