MICROBIOLOGY 4134
Final Exam
NAME:_______________________
PLEASE READ THE QUESTIONS CAREFULLY! ANSWER ALL.
I. Multiple choice (3 pts each) Clearly place an X in the parenthesis next to the
correct answer.
1. Spirochetes include all of the following genera except __________.
XX Bordetella
( ) Treponema
( ) Borrelia
( ) Leptospira
( ) Spirillum
2. The leptospiremic phase of leptospirosis is characterized by all of the following except
_________.
( ) an abrupt fever
( ) severe headaches
XX bacteria in the urine
( ) muscle pain
( ) nausea
3. The colonial morphology of __________ growing on medium is characterized as "a
fried egg".
( ) Bartonella quintana
( ) Coxiella burnetii
( ) Mycobacteria pneumoniae
( ) Borrelia burgdorferi
XX Mycoplasma pneumoniae
4. Which of the following terms connotes prevention?
XX prophylaxis
( ) anaphylaxis
( ) therapy
( ) pathogenesis
( ) none of the above
5. Which of the following is not characteristic of syphilis?
( ) Manifested in three stages
( ) Formation of a hard chancre
( ) Initial rash on the palms and soles
( ) Asymptomatic periods
XX All of the above are characteristic of syphilis.
6. The childhood vaccine DPT immunizes against __________.
( ) Pneumonia
( ) Otitis media
XX Diphtheria
( ) Q - fever
( ) Syphilis
II. True or False; if the statement is false, briefly explain why: (4 pts each).
7. False The toxin of Corynebacterium diphtheriae is coded for by a gene on the host
chromosome.
The toxin is coded for by a lysogenic bacteriophage
8. False The drug of choice for treating Mycoplasma pneumoniae infections is
penicillin.
M. pneumoniae doesn't have a peptidoglycan layer so it is resistant to penicillin.
Tetracyclines are a drug of choice.
9. False The addition of iron to the culture medium of Corynebacterium diphtheriae
stimulates the production of toxin.
Toxin production is repressed by the presence of iron. Iron is a corepressor of the toxin
gene. Deferrated medium stimulates the production of toxin.
10. True The spirochetes flagella is referred to as periplasmic flagella because they lie
between the outer membrane and the peptidoglycan layer.
11. True Urine soaked soil can be a source of the pathogen Leptospira interrogans.
12. False Cat-scratch fever is caused by a species of Coxiella.
Cat-scratch fever is caused by a species of Bartonella.
13. False Syphilis can be transmitted by contaminated door knobs.
Treponema are sensitive to dessication. Door knobs are an inhospitable environment to
the pathogen.
14. False The toxicity of Mycoplasma pneumoniae is determined using the Elek
immunodiffusion assay.
The toxicity of Corynebacterium diphtheria is determined by the Elek assay.
15. False The clinical severity of Trench fever is the severe damage of the blood vessels.
The severity of Rocky mountain spotted fever is due to the damage of the blood vessels.
III. Matching - match the pathogen with the disease. USE CAPITAL LETTERS!
(2 pts each)
A. Lyme disease
B. Q -fever
C. Rocky mountain spotted fever
D. Epidemic typhus
E. Scrub typhus
F. Trench fever
G. Walking pneumonia
H. None of the above
C
D
E
B
A
G
F
H
Rickettsia ricketsii
Rickettsia prowazeki
Orientia tsutsugmushi
Coxiella burnetii
Borrelia burgdorferi
Mycoplasma pneumoniae
Bartonella quintana
Treponema pallidum
IV. Matching - Match the vector with the pathogen. USE CAPITAL LETTERS! (2
pts each)
A. Louse transmitted
B. Tick transmitted
C. chigger transmitted
D. none of the above
B Borrelia hermsii
A Borrelia recurrentis
B Borrelia burgdorferi
D Treponema pallidum
B Rickettsia ricketsii
A Rickettsia prowazekii
D Mycoplasma pneumoniae
D Rickettsia typhii
C Rickettsia tsutsugmushi
D or B Coxiella burnetii (I accepted D or B; the bacteria are inhaled by humans - hence
D and transmitted by ticks between animals - hence B)
Extra Credit (5 pts)
Name a medium used to isolate Corynebacterium diphtheria
Mueller Miller tellurite, Loeffler serum, Tinsdale tellurite, Cystine tellurite or Loeffler's
agar
Describe the mechanism of diphtheria toxin uptake by the host cell and the toxin's effect
on the host cell. Be as specific as possible (10 pts)
1. Binding of the toxin to its host cell receptors
2. Clustering of charged receptors into coated pits and internalized by receptor
mediated endocytosis.
3. Acidification of endosome by ATP-driven proton pumps
4. Insertion of the transmembrane domain into the membrane and transfer of the
catalytic domain into the host cytosol.
5. ADP-ribosylation of EF-2 by the catalytic domain of the toxin.
6. Irreversible inhibition of protein synthesis due to the modification of EF-2.
7. Cell death