Treating and Preventing Two Causes of Diarrhea, Isospora and Cyclospora Infection, in Patients with HIV

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The summary below is from the full report titled "Trimethoprim–Sulfamethoxazole Compared with Ciprofloxacin for Treatment and Prophylaxis of Isospora belli and Cyclospora cayetanensis Infection in HIV-Infected Patients. A Randomized, Controlled Trial." It is in the 6 June 2000 issue of Annals of Internal Medicine (volume 132, pages 885-888). The authors are R.-I. Verdier, D.W. Fitzgerald, W.D. Johnson Jr., and J.W. Pape.

What is the problem and what is known about it so far?

Diarrhea is common in patients with the human immunodeficiency virus (HIV). Infections with the organisms Isospora or Cyclospora frequently cause diarrhea in those patients. The antibiotic trimethoprim–sulfamethoxazole is effective treatment for these infections, usually given at a dose of one tablet four times per day for 10 days. It is unknown whether lower doses or shorter courses of this antibiotic would be effective. Since these infections often come back if the treatment is stopped, patients are usually continued on the antibiotic (secondary prophylaxis). Unfortunately, some patients develop side effects related to the trimethoprim–sulfamethoxazole, and others may be allergic to it. Another antibiotic, ciprofloxacin, has been suggested as an option for treating and preventing infections with Isospora and Cyclospora species.

Why did the researchers do this particular study?

The researchers wanted to compare 1 week of treatment with a lower dose of trimethoprim-sulfamethoxazole and 1 week of treatment with ciprofloxacin, another antibiotic, for patients with HIV infection and diarrhea caused by Isospora or Cyclospora species.

Who was studied?

22 patients with diarrhea due to Isospora species and 20 patients with diarrhea due to Cyclospora species. All of the patients had HIV infection and were under treatment in a clinic in Haiti.

How was the study done?

The researchers assigned study patients to take a pill of trimethoprim—sulfamethoxazole or ciprofloxacin twice daily for 7 days. Patients whose diarrhea got better after 7 days of treatment then took one tablet (of the same antibiotic they had been taking) three times per week for the next 10 weeks to help prevent the diarrhea from coming back. The researchers followed patients to see when diarrhea stopped and whether it came back after the first 7 days of treatment. All of the patients also had stool specimens tested before and after treatment for Isospora or Cyclospora infection.

What did the researchers find?

Diarrhea stopped in all 19 patients who got trimethoprim–sulfamethoxazole. Eighteen of these 19 patients had a negative stool examination after 7 days of treatment. Among the 23 patients who got ciprofloxacin, diarrhea stopped in 20 and 16 had stool examinations that showed no Isospora or Cyclospora infection after treatment. Trimethoprim–sulfamethoxazole stopped diarrhea more quickly than ciprofloxacin. All patients treated with trimethoprim–sulfamethoxazole and 15 of the 16 patients who responded to ciprofloxacin remained free of diarrhea at 10 weeks.

What were the limitations of the study?

This study does not tell us what happens after 10 weeks of preventive therapy.

What are the implications of the study?

Trimethoprim–sulfamethoxazole twice per day for 7 days is an effective treatment for diarrhea caused by Isospora or Cyclospora infection in patients with HIV infection. Ciprofloxacin does not work as well as trimethoprim–sulfamethoxazole but seems to be a reasonable alternative for patients who cannot take trimethoprim–sulfamethoxazole.