levinson questions Flashcards
clinical cases 22: your patient is a 30 yo woman with facial nerve paralysis. she also has fever and headache but does not have a stiff neck. on physical exam, she has a circular, erythematous, macular rash on the back of her thigh. you suspect that she has lyme disease.
of the following tests, which one is the most appropriate to order to confirm a diagnosis of lyme disease?
A: blood culture to grow the organism
B: stain for inclusion bodies within cells involved in the rash
C: test for serum antibody against the organism
D: darkfield microscopy
C
7: each of the following statements concerning endotoxins is correct except:
A: they are less toxic (ie less active on a weight basis) than exotoxins
B: they are more stable on heating than exotoxins
C: they bind to specific cell receptors, whereas exotoxins do not
D: they are part of the bacterial cell wall, whereas exotoxins are not
C
15: which one of the following BEST describes the mode of action of endotoxin?
A: degrades lecithin in cell membranes
B: inactivates elongation factor 2
C: blocks release of acetylcholine
D: causes the release of tumor necrosis factor
D
25: the effects of endotoxin include each of the following except:
A: opsoinization
B: fever
C: activation of the coagulation cascade
D: hypotenison
A
28: each of the following statements concerning exotoxins is correct except:
A: when treated chemically, som exotoxins lose their toxicity and can be used as immunogens in vaccines
B: some exotoxins are capable of causeing disease in purified form, free of any bacteria
C: some exotoxins act in the GI tract to cause diarrhea
D: some exotoxins contain lipopolysaccharides as the toxic component
D
32: each of the following statements concerning endotoxins is correct except:
A: the toxicity of endotoxins is due to the lipid portion of the molecule
B: endotoxins are found in most gram-positive bacteria
C: endotoxins are located outside of the cell wall peptidoglycan
D: the antigenicity of somatic (O) antigen is due to repeating oligosaccharides
B
64: which one of the following host defense mechanisms is the most important for preventing dysentery caused by salmonella?
A: gastric acid
B: salivary enzymes
C: normal flora of the mouth
D: alpha interferon
A
67: which one of the following bacteria has the lowest 50% infectious dose (ID50)?
A: shigella sonnei
B: vibrio cholerae
C: salmonella typhi
D: campylobacter jejuni
A
68: for which one of the following enteric illnesses is a chronic carrier state most likely to develop?
A: campylobacter enterocolitis
B: shigella enterocolitis
C: cholera
D: typhoid fever
D
83: which one of the following organisms that infects the GI tract is most frequent cause of bacteremia?
A: shigella flexneri
B: campylobacter jejuni
C: vibrio cholerae
D: salmonella typhi
D
CC 5: your patient is a 5 yo girl with bloody diarrhea and no vomitting. there is no history of travel outside of san francisco. stool culture grows both lactose-positive and lactose-negative colonies on EMB agar
of the following organisms, which one is most likely to be the cause?
A: shigella sonnei
B: salmonella typhi
C: campylobacter jejuni
D: helicobacter pylori
A
CC 47: your patient is a 22 yo man who has been on a low-budget trip to india, where he ate many of the local foods. he has had a low-grade fever, anorexia, and mild abdominal pain for about a month. you suspect that he may have typhoid fever
if he does have typhoid fever, which one of the following is the least likely laboratory finding?
A: culture of the blood reveals gram-negative rods
B: culture of the stool grows lactose-negative colonies in EMB agar
C: his serum contains antibodies that agglutinate salmonella typhi
D: his serum contains antibodies that cause a positive weil-felix reaction
D
PE1 14: endotoxin is an important underlying cause of septic shock and death, especially in hospitalized patients. regarding endotoxin, which one of the following is the most accurate?
A: it acts by phosphorylating the G stimulating protein
B: it is a polypeptide with an A-B subunit configuration
C: it induces the synthesis of tumor necrosis factor
D: it is found primarily in gram-positive rods
E: it can be treated with formaldehyde to form an effective toxoid vaccine
C
PE2 18: a 70 yo man who is receiving chemotheraphy for leukemia develops a fever to 40 degrees C and has two episodes of teeth-chattering chills, and his blood pressure drops to 80/20 mmHg. Of the following factors, which one is most likely to be the cause of his fever, chills, and hypotension?
A: coagulase B: dipicolinic acid C: glycocalyx D: lipid A E: mycolic acid F: pili G: polysaccharide capsule
D
clincial case 19: your patient is a 10 yo girl who has leukemia and is receiving chemo through an indwelling venous catheter. she now has a fever of 39 degrees C but is otherwise asymptomatic. you do a blood culture, and the laboratory reports growth of staphylococcus epidermidis
which one of the following results is least likely to be found by the clinical laboratory?
A: gram-positive cocci in clusters were seen on gram stain of the blood clusters
B: subculture of the blood culture onto blood agar revealed nonhemolytic colonies
C: a coagulase test on the colonies was negative
D: a catalase test on the colonies was negative
D
120: which one of the following organisms causes diarrhea by producing an enterotoxin that increases adenylate cyclase activity within enterocytes?
A: escherichia coli
B: bacteroides fragilis
C: staphylococcus aureus
D: enterococcus faecalis
A
149: select the one lettered option that is most closely associated with the numbered items.
A: escherichia coli
B: klebsiella pneumoniae
C: salmonella enteritidis
D: proteus mirabilis
is the most common cause of UTI
A
CC case 29: your patient is a 40 yo woman with a severe attach of diarrhea that began on the airplane while she was returning from a vacation in the middle east. she has had multiple episodes of watery, nonbloody diarrhea and little vomiting. she is afebrile. a stool culture reveals only lactose-fermenting colonies on EMB agar.
of the following, which one is the most likely cause?
A: shigella sonnei
B: helicobacter pylori
C: escherichia coli
D: pseudomonas aeruginosa
C
55: each of the following organisms is an important cause of urinary tract infections except:
A: escherichia coli
B: proteus mirabilis
C: klebsiella pneumoniae
D: bacteroides fragilis
D
76: a 65 yo man develops dysuria and hematuria. A gram stain of a urine sample shows gram-negative rods. culture of the urine on EMB agar reveals lactose-negative colonies without evidence of swarming motility. which one of the following organisms is most likely to be the cause of his UTI?
A: enterococcus faecalis
B: pseudomonas aeruginosa
C: proteus vulgaris
D: escherichia coli
B
90: each of the following statements concerning gram-negative rods is correct except:
A: escherichia coli is part of the normal flora of the colon; therefore, it does not cause diarrhea
B: E. coli ferments lactose, whereas the enteric pathogens shigella and salmonella do not
C: klebsiella pneumoniae, although a cause of pneumonia, is part of the normal flora of the colon
D: proteus species are highly motile organisms that are found in the human colon and cause UTI
A
91: a 70 yo man is found to have a hard mass in his prostate, which is suspected to be a carcinoma. 24 hours after surgical removal of the mass, he develops fever to 39 degrees C and has several shaking chills. of the organisms listed, which one is least likely to be involved?
A: escherichia coli
B: enterococcus faecalis
C: klebsiella pneumoniae
D: legionella pneumophila
D
148: select the one lettered option that is most closely associated with the numbered items.
A: escherichia coli
B: klebsiella pneumoniae
C: salmonella enteritidis
D: proteus mirabilis
is frequently implicated in nosocomial infections, is an important cause of community-acquired pneumonia in adults, and has a thick, mucoid capsule
B
150: select the one lettered option that is most closely associated with the numbered items.
A: escherichia coli
B: klebsiella pneumoniae
C: salmonella enteritidis
D: proteus mirabilis
pathogenicity associated primarily with UTI; produces utease
D
156: select the one lettered option that is most closely associated with the numbered items.
A: bacteroides fragilis
B: haemophilus influenzae
C: pseudomonas aeruginosa
D: chlamydia pneumoniae
oxidase-positive gram-negative rod that is an important cause of wound and burn infections
C
561: select the one lettered option that is most closely associated with the numbered items
A: escherichia coli B: shigella sonnei C: salmonella typhi D: salmonella enteritidis E: proteus mirabilis F: pseudomonas aeruginosa G: vibrio cholerae H: campylobacter jejuni I: helicobacter pylori J: bacteroides fragilis
causes wound infections with blue-green pus; is oxidase-positive
F
case 33: your patient is a 30 yo woman who was part of a tour group visiting a central american country. the day before leaving, several members of the group developed fever, abdominal cramps, and blood diarrhea
of the following, which one is the least likely organisms to cause this infection?
A: shigella dysenteriae
B: salmonella enteritidis
C: vibrio cholerae
D: campylobacter jejuni
C
case 35: your patient is a 28 yo man with 3rd degree burns over a large area of his back and left leg. this morning, he spiked a fever to 40 degrees C and had two teeth-chattering chills. a blood culture grows a gram-negative rod that is oxidase-positive and produces a blue-green pigment
of the following, which one is the most likely organism to cause this infection?
A: prevotella melaninogenica
B: pseudomonas aeruginosa
C: proteus mirabilis
D: haemophilus influenzae
B
case 45: your patient is a 6 yo boy with a history of several episodes of pneumonia. a sweat test revealed an increased amount of chloride, indicating that he has CF. he now has a fever and is coughing up a thick, greenish sputum. a gram stain of the sputum reveals gram-negative rods
of the following, which one is the most likely organism to cause this infection?
A: pseudomonas aeruginosa
B: haemophilus influenzae
C: legionella pneumophila
D: bordetella pertussis
A
PE1 6: a 70 yo woman has sustained 3rd degree burns over a significant area of her body. despite appropriate burn care in the hospital, she spiked a fever of 39 degrees C, and the nurse reports blue-green pus on the dressing covering the burned area. gram stain of the pus reveals gram-negative rods, and antibiotic sensitivity tests show resistance to most antibiotics. which one of the following organisms is most likely to cause this disease?
A: nocardia asteroides B: vibrio vulnificus C: vacteroides fragilis D: haemophilus influenzae E: pseudomonas aeruginosa
E
73: for which one of the following bacterial vaccines are toxic side effects an important concern?
A: the vaccine containing pneumococcal polysaccharide
B: the vaccine containing killed bordetella pertussis
C: the vaccine containing tetanas toxoid
D: the vaccine containing diptheria toxoid
B
