A 38-year-old associate professor complained of a 6-week history of intermittent diarrhea, flatus and abdominal pain. She reported the illness began slowly with loose, foul smelling stools. It would spontaneously remit for a few days then recur. The symptoms responded to kaopectate but reappeared soon after treatment stopped.
Question 1 - Single Best Answer
In diagnosing a diarrheal disease, what is one of the most important questions to answer? Bugs Database
A) Is it viral or bacterial?
B) Does it respond to Kaopectate?
C) Is it inflammatory or non-inflammatory?
D) What is the volume of stool lost?
E) Is there pain or no pain?
The patient could not recall any particular circumstances associated with development of symptoms although she stated that she was lately under pressure to complete a grant application. Her family was well with the exception of a 4-year-old daughter who had some loose stools and vomiting which were ascribed to "viral gastroenteritis." Physical examination was normal except for borborygmi and diffuse, mild abdominal tenderness. A single fecal examination was negative for occult blood or leukocytes.
Question 2 - Single Best Answer
What is/are borborygmi? Bugs Database
A) gurgling noises heard on auscultation of the abdomen
B) extreme flatulence
C) a rash on the abdomen
D) rebound tenderness
E) a yellowish color of the skin
Question 3 - Single Best Answer
The professor's diarrheal disease is most compatible with which of the following ? Bugs Database
A) An inflammatory bowel disease caused by an infectious agent.
B) Food poisoning (intoxication).
C) Allergic response or intolerance to specific foods or food additives.
D) Psychogenic changes in bowel function in response to stress.
E) Non inflammatory bowel disease caused by an infectious agent.
Question 4 - Single Best Answer
Considering the apparent non inflammatory nature of the diarrhea, which enteropathogens would you consider as possible causes? Bugs Database
A) Salmonella, Campylobacter jejuni, Shigella
B) Rotovirus, Norwalk virus, enteric Adenovirus
C) Giardia, Cryptosporidia, enterotoxigenic E. coli
D) Yersinia, invasive E. coli, Entamoeba histolytica
Interviews with the patient indicated no obvious source of an infection except possibly the 4-year-old child. Laboratory screening tests (CBC , blood chemistries) were normal. Stool cultures revealed normal flora and were negative for Salmonella, Shigella, Yersinia and Campylobacter. Microscopic examination of a stool specimen confirmed the lack of leukocytes. Examination for protozoan and helminth parasites (ova and parasites)was negative.
Question 5 - Single Best Answer
Would you consider that the cultures and microscopic examination of stool specimens ruled out infection by bacteria (Salmonella, Campylobacter, Shigella, Yersinia) or parasites (E. histolytica, Giardia, Cryptosporidium, Cyclospora) as causes of the diarrheal disease? Bugs Database
A) YES
B) NO
The cause of the diarrheal disease remained unknown even after repeat cultures and special cultures on Campy-agar (for Campylobacter). It was learned that the daughter had attended a day care center in which Giardiasis had been diagnosed in several children. The cause of the daughter's illness had not been determined; it was assumed to be a viral gastroenteritis. At present the child was well and a stool examination for Giardia was negative but suspicion was raised that Giardia could have been the cause of the diarrhea.
Question 6 - Single Best Answer
What aspects of the epidemiology and disease expression in Giardiasis suggest it might be the cause of the diarrheal illness in this patient? Bugs Database
A) Giardiasis is a frequent cause of diarrheal disease. Contamination of drinking water by Giardia cysts (the infective stage) is not uncommon and cysts are resistant to the chlorine concentrations in drinking water.
B) Giardia cysts can be transmitted directly by the fecal-oral route and sanitary conditions in some day care centers have facilitated spread of infection.
C) Giardiasis can be a chronic, asymptomatic infection which becomes symptomatic under conditions that may include emotional stress.
D) The protracted, recurrent diarrhea with foul smelling stools and flatus are typical of Giardiasis and not most bacterial or viral infections.
E) Most of the statements could be applicable to this case.
Two more stool examinations for ova and parasites were negative. Duodenal content was sampled for parasites by means of a string test (Enterotest): a gelatine capsule with an attached string was swallowed and after the string reached the upper intestine it was withdrawn and adherent material from the intestine examined for parasites.
Active flagellated protozoans (trophozoites ) were observed. These were pear shaped, l0-20um in length and in a stained smear were identified as Giardia intestinalis by the shape, paired nuclei and other structures characteristic of this protozoan. Compare the protozoa in a stained smear (arrow) with the drawing of the trophozoite.
Question 7 - Single Best Answer
Why could the string test be positive and the stool examination negative? Bugs Database
A) This was probably a light infection and few if any cysts or trophozoites were passed in the stool.
B) Giardia inhabits the mucosal surface of the upper small intestine and sampling this region is a more efficient method of detecting the infection.
C) The failure to detect Giardia in stool specimens was probably due to inadequate examination of the stool specimens by poorly trained or careless technicians.
After the demonstration of Giardia infection the patient was treated with Quinacrine HCl (Atebrine) and improved rapidly. She had minor complaints of headache and dizziness during treatment but became asymptomatic.
One month later although still asymptomatic a stool examination for parasites was repeated and protozoan cysts were observed. These were identified as Giardia cysts and the patient was retreated.
Subsequently, she has remained asymptomatic and negative for Giardia infection on stool examination.
Question 8 - Single Best Answer
Atabrine sometimes has unpleasant side effects. What other drug could be used to treat Giardia that is also used for some bacterial infections? Bugs Database
A) tetracycline
B) metronidazole
C) ivermectin
D) acyclovir
E) amantadine
Question 9 - Single Best Answer
In the present case the source of infection was not clear but the diarrheal disease was typical of Giardiasis. It is now recognized that the epidemiology and clinical expression in Giardiasis can be diverse. Of the following which have NOT been attributed to Giardia infection? Bugs Database
A) Travellers diarrhea
B) Campers or hikers diarrhea
C) A zoonosis with wild and domestic animal reservoirs
D) A serious, widespread cause of morbidity in children in developing countries
E) Dysentery caused by invasive strains
