Bacteriology 330
Second Examination


10 points.  Describe and illustrate a model of the diphtheria toxin (DTx) as an A/B type bacterial toxin.  Explain how each domain (A, B and T) of the protein behaves when the native toxin enters a cell by receptor mediated endocytosis and releases the enzymatic component of the toxin into the cytoplasm. Include the identification of the receptor and the enzymatic mechanism of action of the toxin in your discussion.



10 points. Name three bacterial diseases and their causes wherein endotoxin (LPS or LOS) is a significant determinant of virulence. What is the major pathology of the disease that represents the host's response to endotoxin?



10 points. What are three bacterial diseases caused by toxins classified as superantigens? How does the disease come about and what is its pathology?



10 points. What are the diseases caused by UPEC, NMEC, ETEC and EHEC (all strains of Escherichia coli)? In each case, what are the two main determinants of virulence of each bacterium?



20 points. Select one of these bacteria Streptococcus pneumoniae, Haemophilus influenzae or Neisseria meningitidis
Identify the bacterium and discuss its role in bacterial meningitis. What is the pathology of the disease? What are the sites of bacterial colonization and invasion? What are the main determinants of virulence of the pathogen? Who is most at risk for the disease? How may the disease be treated and prevented?



10 points. What are the components of each of the following vaccines?

anthrax

cholera

diphtheria

Haemophilus type b meningitis

meningococcal meningitis

pneumococcal pneumonia

staphylococcal septicemia

tetanus

tuberculosis

whooping cough



10 points. Name the bacterium that produces each of the toxins below and describe the effect of the toxin in its host. ("EFFECT" does not mean molecular mechanism of action; it means the result of that)

TOXIN                        BACTERIAL  SOURCE                      EFFECT ON HOST

anthrax
toxin (EF)

botulinum
toxin

cholera
toxin

ST toxin

pertussis AC

pertussis
toxin (Ptx)

pneumolysin

shiga toxin

tetanus
toxin

trachael
cytotoxin



20 points.  In what bacterium and disease are these structures or substances major determinants of virulence? Explain your answer.

elastase 

M-protein

coagulase

alginate slime

enterochelin

TCP pili

P.I (por)

filamentous hemagglutinin (FHA)

poly-D-glutamate capsule

mycolic acid