MDS PREP
What is the typical color of Salmonella colonies on MacConkey agar, except for Sh. Sonnei?
1) Colorless
2) Pink
3) Red
4) Yellow
General Microbiology Answer: 1Salmonella species, excluding Shigella sonnei, which is lactose non-fermenting, will ferment lactose in MacConkey agar, turning the colonies pink due to the formation of acidic end-products
What is the principle behind the Prausnitz and Kustner experiment demonstrating IgE-mediated type I hypersensitivity?
1) Injection of allergen into a non-allergic person causes an allergic reaction.
2) Transfer of serum containing allergen-specific IgE from an allergic person to a non-allergic person induces an allergic reaction.
3) Introduction of allergen-specific T cells into a non-allergic person induces an allergic reaction.
4) Exposure of a non-allergic person to high doses of an allergen induces tolerance.
General Microbiology Answer: 2the Prausnitz and Kustner experiment demonstrated Transfer of serum containing allergen-specific IgE from an allergic person to a non-allergic person induces an allergic reaction. This experiment showed that the allergic state is mediated by a serum component, which we now know is the immunoglobulin E (IgE), and that it can be passively transferred from one individual to another.
What is the primary mechanism of action of the PCR test in diagnosing HIV infection?
1) Amplification of viral RNA or DNA
2) Detection of specific antibodies to HIV
3) Detection of the HIV virus directly
4) Measurement of the immune response to the virus
General Microbiology Answer: 1
The primary mechanism of action of the PCR test in diagnosing HIV infection is the amplification of viral RNA or DNA, allowing for the detection of the virus.
The most efficient method of sterilization in dental practice is
1. ultraviolet radiation
2. moist heat at 121°C for 20 min
3. boiling for 20 mm
4. dry heat at 40° C for 2 hours
Microbiology
Answer: 2
The most efficient method of sterilization in dental practice is moist heat at 121°C for 20 min
Most bacterial endotoxins are composed of
1. pure carbohydrates
2. mucoprotein complexes
3. pure lipids
4. lipoprotein-polysaccharide complexes
Microbiology
Answer: 4
Most bacterial endotoxins are composed of lipoprotein-polysaccharide complexes
The first person becoming sick in an epidemic is called -
1. Primary case
2. Source of infection
3. Reservoir of infection
4. Index case
Microbiology
Answer: 4
The first recognized case in an epidemic outbreak is termed as the index case. Although both the index case and primary case appear to be the same yet they differ slightly. The term primary case refers to the person who first brings a disease into a group of people.
Which of the following is an acidogenic genus found in deep dental caries, that often increases significantly in
the saliva during periods of caries activity?
1.Lactobacillus
2.Candida
3. Actinomyces
4. Rothia
Microbiology
Answer: 1
Lactobacillus is an acidogenic genus found in deep dental caries, that often increases significantly in
the saliva during periods of caries activity
Two important factors for initiation of caries by oral streptococci are
1 production of glucosyl transferase and synthesis of insoluble dextran
2. production of acid and production or protease
3. production of collagenase and pro- duct ion of hyaluronidase
4. fermentation of mannitol and sorbitol and production of protease.
Microbiology
Answer: 1
Two important factors for initiation of caries by oral streptococci are production of glucosyl transferase and synthesis of insoluble dextran