Question 1

In the lab, a dense mixture of the above patient's isolate with plasma on a slide shows clumping. This test correlates with which early process in the pathogenesis of acute endocarditis in a healthy heart?

Accepted Answer

A) Binding to fibronectin 
B) Binding to fibrinogen 
C) Triggering fibrin production 
D) Binding of protein A 
E) Superantigen activity

Question 2

2,5A synthetase is induced by

Accepted Answer

A)  Acyclovir 
B) Amantadine 
C) Cytarabine 
D) Foscarnet 
E) Interferon
F)Ribavirin

Question 3

In March, a nursery school reports an outbreak among the children of a disease characterized by a high-grade (38.8°C to 40°C) fever that starts suddenly and rapidly falls. The children develop a short-lived (1 to 2 days) maculopapular rash that begins on the trunk and spreads to the extremities; the face is spared. The children have mild malaise, but otherwise do not appear ill. The most likely causative agent is

Accepted Answer

A)  Coxsackie A16 virus 
B)  HHV-6 
C)  Parvovirus B19 
D)  Rubella virus 
E)  VZV

Question 4

What is the most likely causative agent of the resident's eye infection in question 31?

Accepted Answer

A)  Aspergillus 
B) Fusarium 
C) Acanthamoeba 
D) Pseudomonas 
E) Staphylococcus

Question 5

Which of the following statements characterize $\gamma2?2$ antibody?

Accepted Answer

A)  It contains a J chain 
B) It contains a secretory piece 
C) It is the initial antibody synthesized after antigen 
D) It contains a hypervariable region 
E) Each of the above statements is characteristic of this antibody

Question 6

A Brazilian who left poverty and moved to Los Angeles 10 years ago has died suddenly of heart failure. Autopsy showed cardiomyopathy due to Chagas' disease. Which vector transferred the trypanosomes?

Accepted Answer

A)  Lice-genus Pediculus 
B) Mites 
C) Mosquitoes-genus Aedes 
D) Mosquitoes-genus Anopheles 
E) Reduviid bugs
F)Sandflies

Question 7

A 15-month-old child living in a religious community that does not vaccinate their children develops meningitis. A Gram-negative rod is seen in the cerebrospinal fluid. What is the most likely causative agent?

Accepted Answer

A) An enterovirus 
B) Escherichia coli 
C) Haemophilus influenzae 
D) Neisseria meningitidis 
E) Streptococcus agalactiae

Question 8

An autoimmune disease characterized by absence of T cells, hypocalcemia, and tetany with lowered cell-mediated immunity is

Accepted Answer

A)  Ulcerative colitis 
B) Multiple sclerosis 
C) Chronic granulomatous disease 
D) Systemic lupus erythematosus (SL
E)  
E) Congenital thymic aplasia (DiGeorge syndrome)

Question 9

Which of the following genetic mechanisms is responsible for the conversion of nontoxigenic strains of Corynebacterium diphtheriae to toxigenic strains?

Accepted Answer

A) Lysogenic phage conversion 
B) In vivo transformation 
C) Reciprocal genetic recombination 
D) Conjugation

Question 10

Which of the following complement components attaches to the crystallizable fragment of immunoglobulin M?

Accepted Answer

A) C2b 
B) C4b2a 
C) C2b. 
D) C5b 
E) C1qrs

Question 11

A non-vaccinated 5-year-old British child just returning from Africa presents with a severe sore throat but little fever. The throat has a grayish exudate on the sides of the pharynx and the child has a swollen neck. Clinical suspicion is of a disease with a circulating toxin inhibiting protein synthesis. What additional tissues are frequently involved?

Accepted Answer

A)  Skin 
B)  Kidneys 
C)  Heart and nerves 
D)  Liver and kidneys 
E)  Ears and sinuses

Question 12

What bacteria can use fermentation pathways but also contain superoxide dismutase?

Accepted Answer

A)  Obligate aerobes 
B)  Obligate anaerobes 
C)  Facultative anaerobes 
D)  Aerobic heterotrophs

Question 13

Both division and differentiation of B cells leading to production of plasma cells require

Accepted Answer

A)  CD4 and CD8 cells 
B) Interleukin (IL)-1 and IL-3 
C) Only IL-1 
D) IL-4 and IL-6

Question 14

An 18-year-old college freshman living in a university residence hall develops severe headache, neck stiffness, and fever. When he cannot be aroused, he is transported to the hospital where a Gram stain of a centrifuged cerebral spinal fluid shows Gram-negative diplococci. A latex particle agglutination test confirms the etiological cause of the bacterial meningitis. Which causative agent is most likely?

Accepted Answer

A) Escherichia coli 
B) Haemophilus influenzae 
C) Listeria monocytogenes 
D) Neisseria meningitidis 
E) Streptococcus pneumoniae

Question 15

When complement is fixed by antigen-antibody complexes, what chemotactic factor for neutrophils is released?

Accepted Answer

A)  C1 
B) C2 
C) C3a 
D) C4b 
E) C789 complex

Question 16

A 33-year-old Mexican fruit picker presents to a free clinic with subcutaneous nodular lesions along the lymphatics from the initial site of trauma 3 weeks ago caused by a plum thorn puncture. What is the nature of the most likely causative agent?

Accepted Answer

A)  Acid-fast organism 
B)  Dimorphic fungus 
C)  Filamentous fungus 
D)  Gram-positive coccus 
E)  Gram-negative rod
F) Helminth

Question 17

An arthropod vector is involved in infection by

Accepted Answer

A) Respiratory syncytial virus 
B) Parvovirus 
C) Reovirus 
D) Parainfluenza virus 
E) Bunyavirus
F)Arenavirus

Question 18

A 29-year-old woman with acquired immunodeficiency syndrome has severe, nonresolving watery diarrhea. It is not gray or greasy. Acid-fast oocysts are seen in the stools. What is the most likely causative agent?

Accepted Answer

A)  Enterohemorrhagic Escherichia coli 
B)  Cryptosporidium 
C)  Enterotoxic Escherichia coli 
D)  Giardia 
E)  Salmonella

Question 19

A neonate with very low Apgar scores dies 2 hours after birth. Autopsy reveals disseminated granulomatous lesions throughout; some are caseating, but they are not calcified. During her pregnancy, the mother most likely had a septicemia caused by

Accepted Answer

A)  Escherichia coli 
B) Group B streptococci 
C) Listeria monocytogenes 
D) Parvovirus B19 
E) Toxoplasma gondii

Question 20

The individual most likely to progress to chronic liver disease following an acute infection is

Accepted Answer

A)  A 50-year-old who becomes HBsAg positive 
B)  A baby born to a chronically active infected HBV mother 
C)  A liver transplant patient infected with HCV 
D)  A recent immigrant who is HEV positive 
E)  A young adult coinfected with HBV and HDV

Exam 11: Travelers Diarrhea: Identifying the Causative Agent