A 23 year old graduate student complaining of fever and pain in the upper right abdomen was admitted to the hospital for diagnosis and treatment.
Question 1 - Single Best Answer
Is this likely an infection problem? Bugs Database
yes no
Question 2 - Single Best Answer
What organ systems might be involved? Bugs Database
neurological renal intestinal respiratory more than one of the above
Question 3 - Single Best Answer
What types of infectious agents can cause abdominal pain? Bugs Database
bacteria protozoa helminths viruses all of the above
The student had just returned from a 3 month group expedition to the Galapagos Islands. In route the group stopped in Costa Rica and many developed diarrhea. With symptomatic treatment (kaopectate) all but the patient recovered in a few days. His diarrhea became worse and within a week he was passing l0-l2 liquid stools per day; he reported cramping, abdominal pain and some stools appeared bloody. He took a medication (Enterovioform) recommended by a local pharmacist and improved but continued to have loose stools and lost weight during the stay in the Galapagos Islands. On the trip back to the university he became feverish and developed the pain the upper right abdomen. He had no previous history of any chronic illness.
Question 4 - Single Best Answer
The bloody stools and fever indicate? Bugs Database
a toxigenic infection food poisoning an inflammatory diarrhea
Question 5 - Single Best Answer
The patient's disease in Costa Rica is likely an infectious diarrhea that could be caused by which of the following agents? Bugs Database
Enterotoxigenic E. coli, a typical cause of traveler's diarrhea Shigella, Salmonella, Campylobacter Entamoeba histolytica Giardia, Cryptosporidia Both B and C
Physical examination revealed a well developed, white male who appeared chronically ill. On admission the following was observed; temperature, 37.6; BP, l34/78; and pulse, 84 and regular. In the following days, the patient exhibited a daily fever (39C) spiking in the afternoon. A smooth, very tender liver edge was palapable 3 fingerbreaths below the right costal margin and there was moderate tenderness over the cecal area. Rectal examination revealed some dark, semiformed stool which was guaiac positive for occult blood. Other physical findings were not remarkable. Blood count indicated a moderate leukocytosis (l7,000) with 70% polymorphonuclear leukocytes. Blood chemistries were within normal limits except for an elevated alkaline phosphatase. Urinalysis was unremarkable.
Further tests were done to identify the cause of the abdominal symptoms. Computerized tomogram (CT) and sonogram of the abdomen indicated a rather large defect in the right lobe of the liver consistant with an abscess and a gastrointestinal series detected an annular defect in the cecal area. A chest X-ray was unremarkable except for an elevation of the right diaphragm. Sigmoidoscoic examination was unrevealing.
Question 6 - Single Best Answer
The examination suggested a liver abscess in the right lobe elevating the right diaphragm and a possible bleeding colonic ulcer(s). What infection(s) would be consistant with these finding and the earlier diarrheal disease? Bugs Database
None. Little probability of any relationship between current liver lesion and earlier diarrheal disease. No specific infection . Bowel ulceration regardless of cause may lead to a pyogenic liver abscess by bowel bacteria. Entamoeba histolytica Rotavirus Leptospirosis
Question 7 - Single Best Answer
To establish a diagnosis of amebic liver abscess? Bugs Database
the presence of E. histolytica in a stool examination would be expected. there would always be a history of colitis. serologic tests could prove that amebiasis was the cause of the abscess. the abscess could be aspirated and the content examined for amebae. a therapeutic trial could confirm a presumptive diagnosis.
In this case repeated stool examinations failed to find diagnostic stages of E. histolytica (cysts or trophozoites). Blood cultures for bacteria were negative and stool cultures demonstrated no pathogens. Serology for amebiasis was not done. Although a diagnosis was not established, the history and clinical findings were considered highly suggestive of amebic abscess and a therapeutic trial was initiated with metronidazole (Flagyl), an effective treatment for amebiasis. Within 5 days there was no fever and less hepatic tendeness. In 6 weeks a liver scan showed reduction in the right lobe defect and within 12 months the liver defect had disappeared. Stool examinations for parasites remained negative and there was no diarrhea or evidence of intestinal bleeding.
This case has presented a common and dangerous complication of amebiasis. It is estimated that there are worldwide 50 million cases of invasive amebic colitis or liver abscess with l00,000 to 400,000 deaths per year.
Even though Entamoeba histolytica must be considered a major intestinal pathogen most infections are asymptomatic with no invasion of the mucosa. E. histolytica is widely distributed infecting approximately l0% of the world's population but invasive amebiasis is a major clinical problem only in certain regions.
Question 8 - Single Best Answer
The reason(s) for the regional differences in the importance of clinical amebiasis are complex. A most important factor is considered to be? Bugs Database
The sanitary conditions and practices which permit repeated, heavy amebic infections. The diet and nature of the intestinal bacterial flora of a population. The malnutrition and low nonspecific resistance which are common in regions endemic for invasive amebiasis. A genetic predisposition for invasive amebiasis in populations native to endemic areas. The presence of strains of E. histolytica differing in pathogenicity and geographic distribution.
Amebiasis can be chronic and extremely variable in clinical expression; disease may suggest ulcerative colitis, carcinoma of the colon, subacute appendicitis, other infectious diarrheas, a variety of chronic bowel disorders in addition to extraintestinal manifestations as liver abscess. Although clinical amebiasis is not common in the USA, it should be considered in a differential diagnosis if there is a history of probable exposure to Entamoeba histolytica. Failure to diagnose and treat invasive amebiasis may have serious consequences for the patient.
Question 9 - Single Best Answer
Diagnosis of amebiasis is often difficult to establish. Of the listed diagnostic procedures which is the most reliable and cost effective? You should know the problems and advantages of each procedure. Bugs Database
Microscopic examination of stool specimens Sigmoidoscopic or proctoscopic examination Serologic tests Stool culture for amebae Detection of amebic antigen in stools
Question 10 - Single Best Answer
The infection cycle and epidemiology are well known. The infective stage, the cyst, is transmitted by the fecal-oral route by contaminated water or food or by direct contact. In evaluating the probability of exposure of a patient to virulent E. histolytica what factors would you consider? Bugs Database
Amebiasis is a tropical infection; exposure outside these areas is rare. Certain farm and domestic animals are reservoir hosts. With adequate water treatment facilities there is essentially no risk of acquiring infection. Amebiasis is not a STD and sexual activity is irrelevant. In areas where clinical amebiasis is common, diagnostic tests for amebiasis are appropriate for any chronic diarrheal disease.