Question

1. The M protein found on the cell walls of Streptococcus pyogenes is a virulence factor because it thwarts what part of our immune system?

  

• it minimizes phagocytosis

• complement proteins are not effective against it

• antibodies that are produced are not effective

• it does not stimulate antibody production

2.  If you run an acid-fast stain on a sputum sample from a patient and the result is positive it indicates that the individual has been infected with

  

• Pseudomonas

• Mycobacterium

• HIV

• Staphylococcus

Answer 1

1. The answer is A, it minimizes the phagocytosis

Explanation: Streptococcus pyogenes is the gram-positive bacteria that causes scarlet fever, M protein is the virulence factor of the bacteria present at C terminal of the surface protein.   It is an antiphagocytic mostly group A Streptococcus bacteria. It binds to factor H and gets destroys complement proteins i.e., C3 convertase, however, antibodies are produced against the M protein and help in opsonization.

2. The answer is B Mycobacterium

   Among the given options Mycobacterium is the correct answer because it is acid-fast bacteria. HIV is a virus, Pseudomonas and Streptococcus are non acid fast bacteria. The mycobacterial cell wall consists of mycolic acids, so when stained by the l-Neelsen staining method, acid-fast bacteria show red-colored under the microscope which indicated as acid fast bacteria..