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Stool cultures are rarely used in diarrhea cases

Clinical guidelines recommend that patients who are suffering from diarrhea provide stool samples for culture. The test results can help pinpoint which, if any, antibiotics can aid the patient. Cultures can also provide valuable clues during a diarrheal disease outbreak, such as the one that occurred earlier this year with Salmonella in tomatoes and peppers. Nevertheless, a new study finds that when patients with diarrhea receive prescriptions for antibiotics, more than likely no stool culture was performed.

Researchers scoured the outpatient and pharmacy records of TennCare, Tennessee's Medicaid program, for visits for diarrhea and antibiotic prescriptions from 1995 to 2004. For the 315,828 visits for diarrhea, stool culture was performed for just 15,820 patients (5 percent). However, antibiotics were prescribed for 32,949 patients (10.4 percent). Of the diarrheal episodes for which antibiotics were prescribed, 3,504 (10.6 percent) had stool cultures performed. Stool cultures were most often provided for whites who lived in urban areas, suggesting this group had better access to health care. Whites were also more likely than blacks to receive prescriptions for antibiotics for their diarrhea.

Although some clinicians see stool cultures as expensive tests that do not yield valuable results, the authors state that the lack of stool cultures for diarrhea cases indicates that antibiotics are possibly being used inappropriately. This can lead to adverse events, high costs, and antibiotic resistance.

This study was funded in part by the Agency for Healthcare Research and Quality (HS13833).

See "Stool cultures and antimicrobial prescriptions related to infectious diarrhea," by L. Rand Carpenter, D.V.M., Stephen J. Pont, M.D., M.P.H., William O. Cooper, M.D., M.P.H., and others in the June 15, 2008, Journal of Infectious Diseases 197, pp. 1709-1712.

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