Two weeks ago, a 5-year-old boy developed diarrhea, which has persisted to the present time despite dietary management. His stools have been watery, pale, and frothy. He has been afebrile. Microscopic examination of his stools is likely to show which of the following?

a. Salmonella sonnei

b. Enterobius vermicularis

c. Sporothrix schenckii

d. Toxoplasma gondii

e. Cryptosporidium

the answer is below…

The United States Medical Licensing Examination, or USMLE for short, is a three-part licensing examination that is required in order to receive a license to practice medicine within the United States.

The USMLE assesses a physician’s ability to apply knowledge, concepts, and principles, and to determine fundamental patient-centered skills that are important in health and disease and that constitute the basis of safe and effective patient care.Examination committees composed of medical educators and clinicians from across the United States and its territories prepare the examination materials each year.

This exam is designed by the Federation of State Medical Boards and the National Board of Medical Examiners to determine whether or not an individual understands and can apply the knowledge necessary to practice medicine safely and intelligently.

The USMLE is actually comprised of three different exams that are referred to as steps, which examine the individual’s knowledge of specific topics related to the field of medicine such as basic science, medical knowledge, medical skills, clinical science, and the application of all of these skills and areas of knowledge in the medical field.

All three steps of the USMLE include a series of computerized multiple-choice questions, but the format of the exam and the information covered in each multiple-choice section is different for each step of the USMLE. The USMLE Step II also has a clinical skills portion that examines an individual’s ability to work with real patients and the USMLE Step III has a computerized patient simulation portion in addition to the multiple-choice section of the exam. In order for an individual to receive a license to practice medicine, the individual must pass all three steps of the USMLE.

Medical doctors with an M.D. degree are required to pass this examination before being permitted to practice medicine in the United States of America

The correct answer is e; Cryptosporidium.

Cryptosporidium has become an important cause of diarrhea in immunocompromised patients, particularly those with AIDS. It can also affect patients who are immunocompetent, and has been recognized as an agent responsible for epidemics of diarrhea in day-care centers. Persistent, nonsuppurative diarrhea as described in the question can be caused by such organisms as amebas, whipworms (trichuriasis), Cryptosporidium, or Giardia lamblia. Salmonella sonnei can be grown in culture, but microscopy is not helpful other than finding fecal leukocytes. Enterobius vermicularis is pinworms, which causes rectal itching and not diarrhea. Sporotrichosis is a fungal infection of the cutaneous and subcutaneous tissue that typically does not cause diarrhea. Acquired Toxoplasma gondii can infest any body tissue. Infection can result in fever, myalgia, lymphadenopathy, maculopapular rash, hepatomegaly, pneumonia, encephalitis, chorioretinitis, or myocarditis. This intracellular parasite does not ordinarily cause diarrhea and is not found in stools.