MICROBIOLOGY
EXAM III-1998               NAME_______________

DIRECTIONS: Answer each question in the space
provided or circle the best answer(s). The value of
each question is indicated in parenthesis. Total of
100 points.

(4 pt) 1. Describe these terms, using specific
examples, in relation to transmission of disease:

active biological vector-organism actually grows in vector. e.g. malaria in mosquitoes.

oligodynamic - coins leak small amounts of metal that inhibit bacteria.

(2 pt) 2. Which organism(s) below commonly use
the digestive tract as a portal of entry ?
a. polio
b. tuberculosis
c. smallpox
d. typhoid
e. gonorrhea

(2 pt) 3. Which organism(s) below commonly use
the unbroken skin as a portal of entry?
a. dysentery
b. cholera
c. Staphylococci
d. dermatophytic fungi

e. syphilis

(2 pt) 4. Which organism(s) below commonly
cross the placenta and can infect the fetus?
a. measles
b. Herpes simplex
c. polio
d. syphilis
e. gonorrhea

(2 pt) 5. What is meant when a person is
described as having a pyemia?
pus producing organisms in the blood

(4 pt) 6. Explain the difference between the terms
sign and symptom, giving specific examples.
sign: objective. measurable. e.g. fever
symptom: subjective. not easily measured. e.g.
                pain.

Exam III, page 2

(4 pt) 7. Define the terms exaltation and
attenuation, explaining how each is
accomplished.
exaltation: increase virulence. pass thru susceptible hosts.
attenuation: decrease virulence. adverse conditions such as lab media.

(4 pt) 8. Define these terms:

streptokinase- Streptococci aggressin for fibrin.

Collagenase - aggressin for breaking down collagen in connective tissue. e.g. Clostridium perfringens

(4 pt) 9. Explain how the following terms increase
the invasive abilities of bacteria.

hyaluronidase - spreading factor. break down hyaluronic acid, cementing material between cells.

leucocidin - destroys WBC.

(2 pt) 10. Explain how endotoxins are involved in
production of fever only.
Gm neg. bacteria in water. Sterilize for injection. They die and release endotoxin. Fever results.

(4 pt) 11. There is a lower incidence of malaria
among Black Americans. Explain.
Sickle cell anemia results in crescent shaped cells which prevent growth of malaria.

Abscence of Duffy factor prevents attachment of malaria to RBC.

(2 pt) 12. Why are the very old more susceptible
to disease?
underlying illness.
decreased efficiency of AB production.

(2 pt) 13. What is the number one factor affecting
an individual's general health?
poor nutrition

Exam III, page 3

(3 pt) 14. Explain why eyes are considered a first
line of defense against disease.
tearing - mechanical flushing
IgA- immunoglobulin A. fights recurring infections.
lysozyme- enzyme breaks NAM-NAG bond in G+.

(2 pt) 15. Leukocytes are a second line of defense
against disease. Explain how eosinophils are
involved in this process.
produce toxins against helminth parasites.

(4 pt) 16. Explain the role of lymphocytes as
defense against disease.
not phagocytic.
B lymphocytes: antibody production.
T lymphocytes: cell-mediated immunity.

(2 pt) 17. Define neutropenia and give an example of a disease that causes it.
decrease in neutrophils. typhoid. TB. Measles, radiation, drugs, influenzae.

(4 pt) 18. Discuss the etiology of tuberculosis and explain why it is important to differentiate between tuberculosis and nontuberculosis mycobacteria.
Mycobacterium tuberculosis
M. bovis
M. Kansassii
M. avium
M. intracellulare complex
MOTTS are more resistant to drugs. May require surgery.

Exam III, page 4

(2 pt) 19. In the United States today, how is tuberculosis normally transmitted?
droplet

(6 pt) 20. Explain these terms as they relate to tuberculosis:

miliary t.b.- in blood

latent t.b.- not actively spitting up organism

osseous t.b.- in bone

(2 pt) 21. The best overall diagnostic test for tuberculosis is? Why?
X-ray. Can detect disease before active.

(4 pt) 22. Explain what a positive Mantoux test would indicate for an individual over 40 years old. For a child under 7 years old.
over 40 yrs, common, so just means exposed. Not active case.
under 7 yrs, rare, so probably has active case.

(2 pt) 23. What antibiotics are normally given for first time treatment of uncomplicated T.B.?
INH and rifampen

(2 pt) 24. What drug is commonly given in 3 drug regimens for tuberculosis since it prevents emergence of resistant strains?
para aminosalicylic acid

(2 pt) 25. For prevention of tuberculosis, what vaccine is commonly used?
Bacillus of Calmette and Guerin

(2 pt) 26. Describe the treatment of leprosy.
tuberculoid form: Dapsone and rifampin
lepromatous form:Dapsone, rifampin, clofazimine

(2 pt) 27. What is the drug of choice for Diphtheria?
erythromycin

(2 pt) 28. What treatment is prescribed for Staphylococcal food poisoning?
None, except very young and very old may need fluid and electrolyte replacement

Exam III, page 5

(2 pt) 29. Discuss the following factors relating to toxic shock syndrome:

causative agent (genus and species)-Staphylococcus aureus

predisposing factors- low Mg, adsorbent material

(4 pt) 30. Explain the difference between a carbuncle and furuncle.
carbuncle is a Staph abscess that involves deeper tissues
furuncles are Staph abscessed that do not involve deeper tissues

(2 pt) 31. What complication of streptococcal pharyngitis results in massive exfoliation and a lobster red rash?
scarlet fever

(2 pt) 32. A late nonsuppurative sequalae of streptococcal pharyngitis that can result in extensive damage to the heart is?
rheumatic heart disease

(3 pt) 33. Describe the following factors related to early onset form of life threatening disease of newborns:

etiology- Streptococcus agalactiae

symptoms- septicemia and pneumonia

mortality rate- 50-80%

(3 pt) 34. Describe the following factors related to botulism food poisoning:

foods associated with- low acid foods e.g. string beans

symptoms- blurred vision, paralysis of diaphragm, stop breathing

treatment- respirator, high enema, antitoxin

(2 pt) 35. In the treatment of tetanus, which antitoxin is usually preferred and why?
TIG. human source.

(3 pt) 36. Explain the difference between immunotherapy and vaccination.
IT is artificial passive immunity. Give patient Ab.
Vaccinations expose patient to Ag. Patient produces Abs.