Testing of urinary Escherichia coli isolates for Shiga toxin production.

Paromomycin: no more effective than placebo for treatment of cryptosporidiosis in patients with advanced human immunodeficiency virus infection. Possible effectiveness of clarithromycin and rifabutin for cryptosporidiosis chemo-prophylaxis in HIV disease. Reply Sir—We thank Dr. White and colleagues for their interest in our article about pa-romomycin and the treatment of AIDS-related cryptosporidiosis [1]. We decided to present the as-treated analysis because, according to our interpretation of the data, there was no trend favoring treatment with paromomycin over administration of placebo. A P value of 0.23 from an intent-to-treat analysis represents an approximately 1 in 4 chance that a difference in efficacy does not actually exist. We did not consider this P value to be low enough to call it a trend. The comments made by Dr. White and colleagues clearly point out the difficulty of conducting clinical research with en-teric pathogens in immunocompromised hosts. Because coinfection with other pathogens is likely when AIDS-related cryptosporidiosis is present, our exclusion criteria included known coinfection at the time of enrollment with any of the following organisms: active cytomegalo-virus (CMV colitis), Mycobacterium av-Campylobacter species. Subsequent to enrollment , there were 3 patients in each arm of the study who had Microspori-dium species detected in their stool. Evaluation of treatment failure encouraged investigation for coinfection but did not require it. Biliary tract involvement is common in cases of cryptosporidiosis. Therefore, it would be quite difficult to exclude patients with biliary tract involvement in clinical trials of possible treatments. In addition, because biliary tract involvement is common, an agent deemed effective for AIDS-related cryptospori-diosis should be effective against all of the manifestations of the disease in the gastrointestinal tract. Concurrent treatment with rifabutin, which might possibly prevent AIDS-related cryptosporidiosis, as has been recently shown [2], was allowed during the study, but treatment with macrolides was not allowed within 14 days of study entry or during the period when paromomycin was being administered. Changes to an-tiretroviral therapy were allowed but seldom occurred. In addition, CD4 cell count showed no discernible effect on the outcome of treatment, because entry criteria required a CD4 cell count of !150 cells/mm 3. In fact, the median CD4 count was !30 cells/mm 3 for both the paro-momycin and the placebo groups. In reviewing our experience with AIDS-related cryptosporidiosis, what we found most interesting is the wide clinical variability of the disease in HIV-infected persons. The ability of the disease to resolve or improve …