11) Which of the following is a defining characteristic of coliforms?
A) They are Gram-positive bacilli.
B) They are found in the intestinal tracts of humans and animals.
C) They ferment lactose.
D) They are strictly anaerobic.
E) They are never pathogenic.
12) Escherichia. coli O157:H7 is primarily associated with which of the following foods?
A) ground beef
B) dairy products
13) The most common cause of traveler's diarrhea is
A) Salmonella enterica.
B) Giardia intestinalis.
C) Cryptosporidium parvum.
D) Escherichia coli.
E) Shigella flexneri.
14) Shigellosis can be differentiated from salmonellosis by the fact that Shigella
A) stimulates intestinal epithelial cells to phagocytize it
B) multiplies in phagocytic vesicles.
C) kills host cells.
D) multiplies in the host cell's cytosol.
E) causes severe diarrhea, abdominal cramps, and fever.
15) The most common bacterial cause of diarrhea that sends people to doctors in the United States is
16) A young woman being treated for serious burns develops severe diarrhea accompanied by intense abdominal pain. She passes several watery, foul-smelling, bloody stools a day. A colonoscopy reveals patches of yellowish lesions in the large intestine. The probable causative agent is
A) Giardia intestinalis.
B) Clostridium difficile.
D) Salmonella enterica serotype Typhi.
E) Vibrio cholerae.
17) The common source of contamination in the majority of cases of staphylococcal food poisoning (intoxication) is
A) dairy products.
C) fecal contamination.
D) the skin of food preparers.
E) contaminated water.
18) Which of the following statements is TRUE with regard to oral herpes?
A) Lesions become more severe with each recurrence.
B) Ninety percent of all cases are caused by human herpesvirus 2 (HHV-2).
C) Lesions can be triggered by emotional stress or physiologic changes.
D) Primary infections are usually characterized by severe lesions.
E) There is an effective cure for oral herpes.
19) Which of the following is the major sign or symptom of mumps?
B) nausea and vomiting
E) difficulty in breathing
20) The viruses responsible for the majority of infant deaths resulting from diarrhea in the world are the