Certain microorganisms are never considered to be members of the normal flora. They are always considered to be pathogens. Which one of the following organisms fits into that category?
A. Streptococcus pneumoniae
B. Escherichia coli
C. Mycobacterium tuberculosis
D. Staphylococcus aureus
E. Neisseria meningitides
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Structure and substances that may enhance the virulence or invasiveness of a bacterium include
A. the capsule
B. hyaluronidase
C. M protein
D. coagulase
E. all of the above
Which statement is true about an exotoxin?
A. It is commonly produced by gram negative bacteria
B. Its 50% lethal dose may be as low as the picogram level
C. It is composed primarily of carbohydrate
D. It is LPS associated
E. It is heat stable
Biological products commonly used for passive immunity are
A. killed bacterial cells
B. the vaccine
C. BCG
D. toxoid
E. antitoxin
The pathogenicity of bacteria mainly depends on bacterial
A. basic and special structures
B. catabolites
C. invasiveness and toxins
D. ways to invade the body
E. number of invading bacteria
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