Deck 11: Travelers Diarrhea: Identifying the Causative Agent

Question 1

A 6-month-old infant is brought to the emergency department (ED) having woken up from a nap with a weak cry, ptosis, unreactive pupils, and the inability to lift her arms. She has had routine well-baby care. There is no sign of physical abuse or rash, and she is afebrile. The physician puts the child on a respiration monitor and calls the infectious disease consultant. What is most likely causing the problem?

A) Viral meningitis
B) Infant botulism
C) Botulism from canned goods that were improperly heated
D) Bacterial meningitis-Listeria monocytogenes
E) Bacterial meningitis-Streptococcus pneumoniae

Answer 1

Infant botulism

Question 2

What is the mechanism of action of the toxin?

A) Cleavage of terminal neuronal docking proteins preventing the release of acetylcholine
B) Blocking the transport of choline into neurons
C) Inhibition of choline acetyltransferase
D) Inhibition of acetylcholinesterase
E) Blocking the synapse of acetylcholine at the ganglia

Answer 2

Cleavage of terminal neuronal docking proteins preventing the release of acetylcholine

Question 3

Five children in Mrs. Thompson's third grade class develop a disease which begins as a bright red rash on the face, turns violet after a few days, then disappears; then, a maculopapular rash appears on the trunk, buttocks, and extremities. It soon fades from the trunk but persists on the thighs and forearms. Two children have also had a slight fever and a sore throat, but none were terribly sick. The genetic material of the most likely causative infectious agent is

A) Double-stranded DNA
B) Single-stranded DNA
C) Double-stranded RNA
D) Single-stranded RNA
E) Segmented single-stranded RNA

Answer 3

Single-stranded DNA

Question 4

If one were to create a single antigen vaccine to have prevented the outbreak and for use as a vaccine in women prior to pregnancy, what viral molecule would be most likely to lead to the production of successful neutralizing antibodies?

A) Matrix protein
B) Capsid protein
C) Surface glycopeptide
D) Polymerase

Question 5

Which of the following bacterial compounds is important in colonization?

A) Diaminopimelic acid
B) Calcium dipicolinate
C) "O" antigens
D) Pilin
E) Porins

Question 6

What is the function of the cyclic AMP binding proteins in facultative bacteria?

A) To decrease levels of elongation factors
B) To enhance RNA polymerase activity
C) To facilitate binding of repressor proteins
D) To increase transcription initiation
E) To suppress the Pasteur effect

Question 7

An 18-year-old male college student came to the Student Health Services complaining of a sore throat, fatigue, and difficulty in swallowing. A physical examination showed an enlarged spleen; a palpable, tender liver; and swollen cervical lymph nodes. His blood is positive for heterophile antibody. What would you expect to see in a blood smear?

A) Atypical T cells called Downey cells
B) Gram-positive rods
C) Gram-negative rods
D) Mononuclear cells with Cowdry type A inclusions
E) Multinucleated giant cells

Question 8

A 17-year-old girl presents to your gynecology clinic with complaints of recurring pelvic pain. A probable diagnosis of pelvic inflammatory disease is made. She is a senior at a suburban high school, is involved in orchestra, and has been on the honor roll most years. She does not do drugs. She has had an equally "squeaky clean" type of boyfriend since last fall, and 6 months ago they had unprotected sex on three occasions. What is the most likely causative agent?

A) Candida albicans
B) Chlamydia trachomatis
C) Neisseria gonorrhoeae
D) Haemophilus ducreyi
E) Treponema pallidum

Question 9

A 26-year-old man presents with cellulitis two days after he is bitten by his girlfriend's cat. What is the most likely dominant organism involved in the infection?

A) Bartonella henselae
B) Calymmatobacterium granulomatis
C) Pasteurella multocida
D) Toxoplasma gondii
E) Clostridium tetani

Question 10

What compound is only found in Gram-positive bacteria?

A) Capsule
B) Lipopolysaccharide
C) Outer membrane
D) Peptidoglycan
E) Teichoic acid

Question 11

The parents of an 18-month-old girl appear at the emergency department of a hospital with their daughter, who had an abrupt onset of vomiting and incidences of watery diarrhea. The symptoms began 2 days previously at her day care center. She refuses to eat or drink and is very lethargic. What property of the infectious agent causing these symptoms allowed the preparation of a vaccine that could have prevented them?

A) Ability to survive as a temperaturesensitive mutant
B) Identification of an enterotoxin
C) Loss of colonization factors
D) Manipulation of "O" antigens
E) Segmented genetic material

Question 12

A 22-year-old female student complains of excessive fatigue for the past 2 months. Polyarthralgia and vasculitis is noted on examination. Lab tests reveal multiple autoantibodies including antidouble-stranded DNA. The most logical diagnosis is

A) Hashimoto's thyroiditis
B) Multiple myeloma
C) Sjögren's syndrome
D) Lupus erythematosus

Question 13

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?

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

Question 14

An elderly woman presents with chronic fatigue, difficulty sleeping, a rapid heartbeat, and bulging eyes. Lab tests revealed autoantibodies to thyroid-stimulating hormone. The most likely diagnosis is

A) Hashimoto's disease
B) Cancer of the thyroid
C) Graves' disease
D) Pernicious anemia

Question 15

A 50-year-old woman from Key West presents with a mosquito-borne viral disease in which her antiviral antibodies from an infection nearly a decade ago were thought to have an "enhancing" effect so that the current reinfection with the virus caused a more serious bleeding disease. What is the causative agent?

A) Coxsackie A virus
B) Dengue virus
C) Hanta virus
D) Rubella virus
E) West Nile virus

Question 16

A 22-year-old woman presents with vaginal itching and erythema as well as a discharge which is thick and white. External erythema is also present with discrete pinpoint lesions off the edge. The discharge pH is 4.7 (normal). Amine test is negative as is the genetic probe test for Neisseria. What is the most likely cause?

A) Bacterial vaginosis
B) Overgrowth of Gardnerella vaginalis
C) Trichomonas vaginalis
D) Chlamydia trachomatis
E) Candida albicans

Question 17

An antibiotic that has a $\beta$ -lactam ring in its structure is

A) Tetracycline
B) Cephalosporin
C) Streptomycin
D) Erythromycin
E) Griseofulvin
F) Bacitracin

Question 18

Which bacterial gene transfer process would be inhibited by free extracellular exonucleases?

A) Conjugation
B) Generalized transduction
C) Specialized transduction
D) Transformation
E) Transposition

Question 19

After a trip to Peru to adopt a 6-month-old baby, a 32-year-old woman and her new baby both develop profuse, watery diarrhea with flecks of mucus. Both are hospitalized because of the severity and rapidity of the dehydration, but neither one is febrile. What is the most likely causative agent?

A) Campylobacter jejuni
B) Escherichia coli O157
C) Salmonella typhi
D) Vibrio cholerae
E) Shigella dysenteriae

Question 20

A 19-year-old pregnant student presents at her health service allergy clinic with rhinorrhea, sneezing, itching, and conjunctivitis. A RAST test finds IgE antibodies to ragweed antigens. A characteristic of this condition is

A) IL-4 mediated IgE synthesis has increased
B) Desensitization can occur with repeated injection of small doses of IgE
C) Drugs that elevate cGMP can reduce symptoms
D) Placental transfer of ragweed antibody can sensitize her unborn child

Question 21

IgA is largely responsible for protection of the respiratory and intestinal mucosal tract. Effective protection is dependent on the action of a secretory piece which

A) Facilitates the passage of IgA out of the plasma cell
B) Facilitates the formation of the IgA dimer
C) Is released by IgA causing an inflammatory response
D) Is a poly Ig transport receptor on mucosal epithelial cells

Question 22

A noncompliant 70-year-old HIV-positive man with a $CD4^+$ cell count of $40/mm^3$ presents with a pulmonary infection caused by an organism that requires 4 weeks to grow on Lowenstein-Jensen medium. What is the best descriptor of the most likely causative agent?

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

Question 23

An individual is known to have chronic hepatitis B disease. Which serological marker should be monitored to determine if the blood contains the infectious virus?

A) HBcAg
B) HBeAg
C) HBsAg
D) IgG HBs
E) IgM HBc

Question 24

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

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

Question 25

HLA II molecules play an important role in the immune response. One of their functions is

A) To present peptidic epitopes to $CD4^+$ T helper cells
B) To present peptidic epitopes to $CD8^+$ T helper cells
C) To interact with an epitope on the membranes of most nucleated cells
D) To interact with the gene regions: DP, DQ, DR

Question 26

One of the hallmarks of viral infections of the temporal lobe of the brain is

A) Holes in the parenchyma
B) Koplik spots
C) Maculopapular rash along dermatomes
D) Perivascular cuffing

Question 27

A 63-year-old alcoholic presents complaining of chest pain, fever, shaking chills, cough, and myalgia. She was very cold two nights ago and says she has felt "poorly" ever since. Her cough is producing rust-colored, odorless, mucoid sputum. Her temperature on admission is 40°C. Her white blood cell count is 16,000 cells/mm3 and is predominantly neutrophils with an overall left shift. An $\alpha$ -hemolytic, lancet-shaped, Gram-positive diplococcus is isolated on blood agar. What is the most likely causative agent?

A) Legionella pneumophila
B) Klebsiella pneumoniae
C) Mycoplasma pneumoniae
D) Neisseria meningitidis
E) Streptococcus pneumoniae

Question 28

Pepsin digestion of the IgG antibody against tetanus toxoid will

A) Result in loss of the ability to form a lattice with the toxoid
B) Produce two Fab molecules and one Fc fragment
C) Result in a (Fab) 2 molecule and destruction of the Fc fragment
D) Result in the loss of the Ch 1 heavy chain constant domain

Question 29

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?

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

Question 30

The Pap smear of a 19-year-old female college soccer player contains koilocytotic cells. The disease associated with the appearance of the cells could most likely have been prevented by previous administration of a(n)

A) Inactivated virus vaccine
B) Inactivated whole cell vaccine
C) Live attenuated virus vaccine
D) Recombinant vaccine containing viruslike particles
E) Toxoid vaccine

Question 31

A 9-year-old girl presents with bloody diarrhea following a neighborhood barbeque. Her mother said the hamburgers were undercooked. Ultimately, a diagnosis of O157 strain of E. coli is made. Where are the O antigens found? In

A) Capsule
B) Lipopolysaccharide
C) Lipoprotein
D) Mesosome
E) Peptidoglycan
F) Teichoic acid

Question 32

What is transferred when an $F^+$ cell is crossed with an $F^-$ cell?

A) Only some bacterial chromosomal genes
B) Generally the whole bacterial chromosome
C) Only the fertility factor DNA
D) Both the plasmid and chromosomal genes
E) No genes

Question 33

Goodpasture's syndrome is characterized by glomerulonephritis in genetically susceptible individuals. The responsible antigen is

A) A glycoprotein dispersed uniformly on the glomerular basement membrane
B) A circulating antigen-antibody complex
C) Rheumatoid factor
D) A complement (C'5a) induced influx of neutrophils

Question 34

A 35-year-old male AIDS patient is hospitalized with a serious pneumonia. His x-ray shows an interstitial pattern of infection, and lab analysis of his sputum indicates the presence of giant cells. Which drug is the best one to be utilized to treat this infection?

A) Foscarnet
B) Ganciclovir
C) Ribavirin
D) Trifluridine
E) Zidovudine

Question 35

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

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

Question 36

A receptor for the human immunodeficiency virus (HIV) is

A) CD2
B) CD3
C) CD4
D) CD8
E) CD25

Question 37

A patient with hay fever switches from IgG formation to IgE production via

A) Interleukin (IL)-1
B) IL-2
C) IL-3
D) IL-4
E) IL-5

Question 38

An outbreak of respiratory disease that leads to pneumonia occurs in a nursing home. It is characterized by an interstitial x-ray pattern and both amantadine and zanamivir are effective treatments. What is the causative agent?

A) Influenza A virus
B) Influenza B virus
C) Legionella pneumonia
D) Metapneumovirus
E) Mycoplasma pneumonia

Question 39

Which of the following is the principal immunoglobulin (Ig) in exocrine secretions?

A) IgA
B) IgG
C) IgM
D) IgD
E) IgE

Question 40

A 3-year-old child develops acute glomerulonephritis following impetigo. The bacterium is a catalase-negative, Gram-positive coccus that has M12 surface protein. What is the most likely causative agent?

A) Enterococcus faecalis
B) Staphylococcus aureus
C) Staphylococcus epidermidis
D) Streptococcus agalactiae
E) Streptococcus pneumoniae
F) Streptococcus pyogenes

Question 41

After extensive oral surgery, a 68-year-old patient who had rheumatic fever as a child and who did not take the prescribed perioperative prophylactic antibiotics subsequently developed subacute infective endocarditis. Which of the following is the most likely causative agent?

A) Enterococcus faecalis
B) Staphylococcus aureus
C) Viridans streptococci
D) Streptococcus agalactiae
E) Streptococcus pneumoniae
F) Streptococcus pyogenes

Question 42

A 37-year-old woman who is on chemotherapy is admitted in respiratory distress. She had signs of focal central nervous system (CNS) lesions early in the day and is now in a comatose state. Both the CNS and pulmonary biopsies show dichotomously-branching (at an acute angle), septate hyphae. What is the most likely underlying condition?

A) $CD4^+$ cell count less than 200
B) Ketoacidotic diabetes
C) Multiple myeloma
D) Severe neutropenia
E) Sickle cell disease

Question 43

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

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

Question 44

When IgG is cleaved by papain, which of the following fragments appear?

A) Two monovalent antigen-binding fragments (Fab)
B) Two Fab fragments that contain only the variable section of the heavy chain
C) Two Fab fragments that contain only the variable section of the light chain
D) Two Fc (crystallizable) fragments and one Fab fragment

Question 45

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?

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

Question 46

N-acetylmuramic acid is located in

A) Lipopolysaccharide
B) Lipoprotein
C) Outer membrane
D) Peptidoglycan
E) Teichoic acid

Question 47

A 24-year-old Peace Corps worker is sent back to the United States from East Africa because he has had a very high fever. African sleeping sickness is diagnosed. How is it transmitted?

A) Tsetse fly bite
B) Invasion of skin in water
C) Respiratory droplets and direct mucosal contact
D) Mosquito bite
E) Reduviid bug bite
F) Sandfly bite

Question 48

A 48-year-old woman who presents with muscle weakness and a thymoma is suspected of having myasthenia gravis. If correct, lab tests should show autoantibody against

A) Thyroid-stimulating hormone
B) Acetylcholine receptor
C) Intrinsic factor
D) Rheumatoid factor

Question 49

A patient who is diabetic and has been in the hospital twice in the last year presents with a boil on his neck. You drain it, but because of his hospitalizations you realize that there is a good chance that it could be a drug-resistant strain and order direct Gram stain cultures, as well as susceptibility testing and anaerobic culture. The preliminary report comes back with Gram-negative cocci in clusters. This puzzles you, so you call the lab supervisor who realizes the stain was done by a new lab person. It turns out to be Staphylococcus aureus. What mistake in the Gram stain did the new person most likely make to produce pink cocci with no hint of purple?

A) She left the safranin on too long
B) She decolorized a bit too long
C) She forgot the decolorization completely
D) She forgot the Gram's iodine
E) She forgot the safranin

Question 50

An asymptomatic 35-year-old male Catholic missionary has returned to the United States following 12 years in rural Mexico. His routine physical examination shows elevated transaminases. His medical history in Mexico was unremarkable except for an auto accident requiring a blood transfusion of 3 pints of blood. What definitive lab test should be performed to determine what effective treatment should be prescribed?

A) Blood culture on MacConkey media
B) Differential cytology of the blood
C) Electron microscopy for Dane particles
D) Molecular genotyping of circulating virus
E) Serology for levels of IgG HEV

Question 51

Which of the following virulence factors is produced by several genera of bacteria that are notable mucosal colonizers including S. pneumoniae?

A) Elastase
B) Hemagglutinin
C) Immunoglobulin A protease
D) Mucinase

Question 52

A sexually transmitted disease with no genital signs or symptoms is

A) Epstein-Barr virus
B) Hepatitis B virus
C) Human T-cell lymphotropic virus
D) Parvovirus B19

Question 53

A live attenuated vaccine is not available for protection from HPV-associated cancer because

A) The virus does not survive in the mouth and oropharynx
B) E6 and E7 viral proteins are associated with oncogenesis
C) Viral membrane receptor glycoprotein is very unstable
D) The virus only grows in human cells

Question 54

There is an outbreak of watery diarrhea in six members of a party of 20 who ate at a Chinese restaurant the day before. Fried rice is implicated. What is the most likely causative agent?

A)Bacillus cereus
B)Giardia lamblia
C)Norwalk agent
D)Rotavirus
E)Salmonella enteritidis
F)Staphylococcus aureus

Question 55

A neonate develops meningitis at 7 days of age. Her mother is 16 years of age, single, has had multiple sexual partners without barrier protection, and lives in the United States. The baby was born 23 hours after the mother's amniotic sac ruptured. What is the most likely causative agent?

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

Question 56

An emerging pathogen has been associated with serious lower respiratory tract disease. Both amprenavir and saquinavir have been demonstrated to be effective in treating the infection. What step in the pathogenesis of the infectious agent is affected by these drugs?

A)Cross-linking of the agent's cell wall
B)Inhibition of the agent's DNA replication
C)Inhibition of the agent's reverse transcriptase
D)Premature release of the agent's mRNA from the translation complex
E)Processing of polyproteins

Question 57

In January a 4-month-old girl is seen by her family physician. Her mother noted that she has been coughing and has had a slight fever for 3 days and recently developed difficulty breathing that is characterized by wheezing. She has a runny nose composed of clear fluid with some cells present. X-rays show her lungs are clear of infection. Examination of the nasal discharge is likely to show what entity to confirm diagnosis?

A)Eosinophilic cytoplasmic inclusions in cells
B)Gram-positive cocci
C)Gram-negative coccobacilli
D)Multinucleated giant cells
E)Secretory IgA heterophile antibody

Question 58

Mobile genetic elements that code for antibiotic resistance genes in bacteria but are incapable of self-replication are

A)Mesosomes
B)R factor
C)Temperate RNA phages
D)Transposons
E)Virulent DNA phages

Question 59

What is the mechanism of action of the aminoglycosides?

A)Damage the membrane
B)Inhibit the DNA gyrase
C)Inhibit mycolic acid synthesis
D)Block initiation complex
E)Inhibit peptide chain elongation

Question 60

Which of the individuals listed below is the most likely to develop a serious disease from West Nile virus?

A)A 4-month-old hospitalized with a serious RSV infection
B)A 3-year-old with croup
C)A 21-year-old college student returning from a vacation in Costa Rica
D)A 24-year-old tour guide in the four corners of the southwestern United States
E)A 55-year-old camper returning from a 2-week wilderness experience in Minnesota

Question 61

In the following pairs of organisms, which two are easiest to distinguish from each other by Gram stain?

A)Bacillus and Clostridium
B)Salmonella and Shigella
C)Haemophilus and Escherichia
D)Corynebacterium and Lactobacillus
E)Listeria and Proteus

Question 62

Two physicians traveling in Central America develop what they self-diagnose as ET Escherichia coli. What is responsible for the fluid and electrolyte disruption?

A)Adherence causing palisade layers of the bacterium on the surface of the small intestine
B)Exotoxin that inhibits protein synthesis by nicking 60S ribosomal subunits
C)Entrance through intestinal M cells and migration through the tissue via actin polymerization/"jetting"
D)Exotoxin that inhibits protein synthesis by blocking elongation factor 2
E)Exotoxin that causes an increase in cyclic adenosine monophosphate
F)Exotoxin that inhibits protein synthesis by nicking 60S ribosomal subunits.

Question 63

In a high-frequency recombination (Hfr) cross with an $F^-$ bacterial cell, each having a single DNA molecule, what is the most likely outcome?

A)Bacterial genes will be transferred from the Hfr cell to the $F^-$ cell, but there will be no change in the "sex" of either cell
B)Some genes will be transferred and the recipient cell will become Hfr
C)Only plasmid genes will be transferred
D)Each cell may acquire genes from the other

Question 64

A new reverse transcriptase has been discovered. In addition to its effect on HIV disease, it should be checked for its potential in treating

A)Infectious hepatitis
B)Infectious mononucleosis
C)Measles
D)Serum hepatitis
E)Shingles

Question 65

A recent Asian immigrant was found to be positive for the tuberculin skin test. The positive result most likely can be attributed to

A)Antibody against mycobacteria plus complement
B)Previous BCG vaccination
C)Activation of previously sensitized NK cells
D)Niacin production by PPD

Question 66

A 60-year-old man who traveled to Haiti and took prophylactic chloroquine but stopped just as he left the region now has developed Plasmodium vivax malaria. What stage(s) was/ were not eliminated because he stopped taking the drug early?

A)Erythrocytic schizonts/merozoites
B)Sporozoites
C)Bradyzoites
D)Liver schizonts/merozoites
E)Gametocytes

Question 67

A characteristic of patients with systemic lupus erythematosus (SLE) is

A)A linear deposition of immunoglobulin on the glomerular basement membrane
B)Antibody against the thyroid receptor
C)Vasculitis
D)Absence of antibodies to double-stranded DNA
E)Each of the above characteristics is present

Question 68

In January, a 74-year-old woman is brought to the hospital emergency department by her husband, who states that she had complained of a fever and headache during the past week. During the last 2 days, she has been confused and cannot perform her daily chores. Her physical examination indicates some weaknesses in her left side and her head MRI shows necrosis in the right temporal lobe. What is the most likely causative agent?

A)Coxsackie A16 virus
B)HSV-1
C)Rabies virus
D)West Nile virus
E)Western equine encephalitis virus

Question 69

A 57-year-old man presents with paranasal swelling, hemorrhagic exudates in the eyes and nares, and mental lethargy. Nonseptate hyphae are found invading the tissues. Rhinocerebral Mucor infection (zygomycosis) is diagnosed. What is the most likely underlying condition?

A)C5 to C8 deficiencies
B)Epstein-Barr virus infection
C)Hepatitis A infection
D)Hepatitis B infection
E)Ketoacidotic diabetes
F)Severe neutropenia

Question 70

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?

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

Question 71

In question 17, the substance found in the patient's CSF that gives the positive agglutination test also plays a role in the pathogenesis. What is that role?

A)It inhibits phagocytic uptake in the bloodstream of a nonimmune individual
B)It promotes invasion of the bloodstream
C)It enhances opsonization
D)It causes a strong inflammatory response loosening tight junctions, allowing invasion of the central nervous system
E)It allows binding to the vascular endothelium, triggering the uptake and passage into the CNS

Question 72

Repeated Neisseria meningitidis septicemias in an individual should raise physician awareness of what underlying condition?

A)C5 to C8 deficiencies
B)Chronic hepatitis B infection
C)Ketosis-prone diabetes
D)Multiple myeloma
E)Severe neutropenia

Question 73

Which of the following interleukins is an endogenous pyrogen?

A)IL-1
B)IL-2
C)IL-3
D)IL-4
E)IL-5

Question 74

What is the defect in a 5-year-old boy with chronic granulomatous disease?

A)Inability of polymorphonuclear leukocytes (PMN) to ingest bacteria
B)Reduced levels of the fifth component of complement (C 5a)
C)Dysgammaglobulinemia
D)Inability of PMNs to kill already ingested bacteria

Question 75

A 28-year-old neutropenic woman with Pseudomonas aeruginosa septicemia develops shock. What triggers the shock?

A)Catalase
B)Lipid A
C)Flagella from Gram-negative bacteria
D)O-specific polysaccharide side chain of endotoxin
E)Teichoic acid-peptidoglycan fragments

Question 76

A 5-year-old Somali immigrant girl presented to the local Family Medicine Clinic with a 2-day history of headache, earache, and swallowing difficulty. Physical examination showed bilateral swelling of the parotid glands. She had been in this country for 4 months and had started her childhood vaccinations 2 weeks ago. The genetic nature of the pathogen causing her disease is

A)Double-stranded DNA
B)Double-stranded RNA
C)Negative-sense RNA
D)Positive-sense RNA
E)Single-stranded DNA

Question 77

A female infant is born to a 16-year-old mother. The infant shows signs and symptoms of hepatosplenomegaly, jaundice, low birth weight, chorioretinitis, and microcephaly. The mother appears healthy and reports an unremarkable pregnancy except for a period during the third month when she developed a fever, sore throat, and became extremely fatigued for a period of 10 days. The most likely causative pathogen for the infant's disease is

A)CMV
B)Listeria monocytogenes
C)Parvovirus B19
D)Rubella virus
E)Treponema pallidum

Question 78

Demyelinating lesions, increased IgG in spinal fluid, and chronic relapsing occurrences are characteristic of which autoimmune disease?

A)Ulcerative colitis
B)Multiple sclerosis
C)Systemic lupus erythematosus (SLE)
D)Congenital thymic aplasia
E)Myasthenia gravis

Question 79

An outbreak of pneumonia occurs in a pediatric intensive care facility. A negative single-stranded RNA virus lacking hemagglutinating and neuraminidase activity is isolated. The virus is a

A)Adenovirus
B)Influenza A virus
C)Parainfluenza virus
D)Respiratory syncytial virus

Question 80

Infection with which of the following organisms is more often noted for the production of a lymphocytosis rather than a mononucleosis?

A)Epstein-Barr virus
B)Bordetella pertussis
C)Human immunodeficiency virus
D)Listeria monocytogenes