MDS PREP
The most pronounced effect on the oral microflora of a reduction in rate of salivary flow is a
1. significant increase in number of oral bacteria
2. shift towards a more acidogenic microflora
3 significant decrease in number of oral bacteria
4 shift towards a more aerobic micro flora
Microbiology
Answer: 2
The most pronounced effect on the oral microflora of a reduction in rate of salivary flow is a shift towards a more acidogenic microflora
What type of differentiation is associated with a diphtheria bacilli that ferments glycogen and starch?
1) Gravis
2) Intermedius
3) Mitis
4) Avirulent
Diphtheria bacilli that ferment glycogen and starch are classified as Mitis.
What is the primary clinical significance of a deficiency in C5 to C8 components of the complement system?
1) Hereditary angioneurotic edema
2) Recurrent pyogenic infections
3) Systemic lupus erythematosus
4) Neisserial infections
Recurrent pyogenic infections are associated with a deficiency in C5 to C8 components of the complement system.
Which test uses live Treponema pallidum as the antigen?
1) TPA test
2) TPI test
3) FTA test
4) TPHA test
General Microbiology Answer: 2
TPI test: The Treponema pallidum immobilization (TPI) test involves using live T. pallidum as an antigen to detect antibodies in the patient's blood serum.
What is the primary cause of cutaneous anthrax?
1) Inhalation of spores
2) Entry through the skin
3) Ingestion of contaminated food
4) Contact with infected animals
Cutaneous anthrax is primarily caused by entry through the skin, often through abrasions or cuts.
What is the role of the Vi antigen in the pathogenesis of typhoid fever?
1) It aids in colonization of the intestinal mucosa.
2) It confers resistance to antibiotics.
3) It is involved in the production of toxins.
4) It allows the bacteria to evade the host's immune response by inhibiting phagocytosis.
General Microbiology Answer: 4The role of the Vi antigen in the pathogenesis of typhoid fever is it allows the bacteria to evade the hosts immune response by inhibiting phagocytosis: The Vi antigen is a polysaccharide capsule found in some strains of S. typhi that helps the bacteria avoid phagocytosis by host immune cells. This contributes to the bacterias ability to survive and proliferate within the human body.
Which of the following statements is true about the colony morphology and cultural characteristics of Anthrax bacilli?
1) Anthrax bacilli are motile and produce a turbidity in broth.
2) The Medusa head appearance is seen in non-virulent strains of anthrax bacilli.
3) Virulent capsulated strains form smooth colonies.
4) The inverted fir tree appearance is characteristic of Anthracoid bacilli.
The Medusa head appearance is characteristic of virulent strains of anthrax bacilli, not non-virulent strains.
Which of the following is a feature of the immune response involving HLA class I antigens?
1) They activate B cells
2) They present antigens to CD4+ T cells
3) They are involved in graft rejection
4) They are only present in the thymus
General Microbiology Answer: 3HLA (Human Leukocyte Antigen) class I antigens are crucial in the immune response to infections and also play a significant role in graft rejection. They present antigens to CD8+ T cells (cytotoxic T cells), which then target and destroy infected or foreign cells. While they do not directly activate B cells or CD4+ T cells, they are involved in the recognition of cells by the adaptive immune system and thus are important in the overall immune response.