Answer:USMLE step 2 Mcq 201:An immuno-competent patient develops diarrhea




Correct Answer: E

Cryptosporidiosis. Oocysts of Cryptosporidium parvum (acid-fast stain). Against a blue-green background, the oocysts stand out in a bright red stain. Sporozoites are visible inside the 2 oocysts to the right. The most widely used diagnostic test is the modified acid-fast or Kinyoun stain. It is used to detect Cryptosporidium in stool samples. Several immunofluorescent assays are also available, which test for antibodies to the parasite in the blood. Some pharmaceutical companies have produced rapid-result commercial assays, which are moderately successful (~75% detection rate). Polymerase chain reaction (PCR) techniques might also prove to be effective in diagnosing infection.  Treatment usually is not required for cryptosporidiosis in patients who are immunocompetent, and no clinical trials have convincingly demonstrated the efficacy of antimicrobics


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