MDS PREP
Dry heat sterilization of paper points without incineration is accomplished at
1. 160°C for 2hours
2. 120°C for l hour
3. 100°C for 2 hours
4. 200°C for 1 hour
Microbiology
Answer: 1
Dry heat sterilization of paper points without incineration is accomplished at 160°C for 2hours
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.
General Microbiology Answer: 2
The Medusa head appearance is characteristic of virulent strains of anthrax bacilli.
Example Test for type IV hypersensitivity:
1) Coagulase test
2) Mantoux test
3) Schick test
4) Elek’s test
Microbiology Answer: 2
A classic example of delayed type IV hypersensitivity is the Mantoux tuberculin test in which skin induration indicates exposure to tuberculosis.
This reaction is called "delayed hypersensitivity" because it is mediated by sensitized CD4+ T lymphocytes which process antigens in association with class II HLA molecules and release lymphokines.
The lymphokines promote a reaction (especially mediated through macrophages) beginning in hours but reaching a peak in 2 to 3 days.
Hypersensitivity reactions with this mode of action include:
Granulomatous diseases (mycobacteria, fungi)
Tuberculin skin reactions
Transplant rejection
Contact dermatitis
Cytotoxic T lymphocyte (CTL) mediated responses: CD8+ T cells are generated and lyse specific cells. Class I HLA molecules play a role. Reactions with this mode include:
Neoplastic cell lysis
Transplant rejection
Virus-infected cell lysis
In concentrations usually applied for sterilization purposes, ethylene oxide is preferable to formaldehyde becuase it is
1. more readily polymerized to an active form
2. less toxic
3. less likely to form an explosive mixture with air
4. more penetrating
Microbiology
Answer: 4
In concentrations usually applied for sterilization purposes, ethylene oxide is preferable to formaldehyde becuase it is more penetrating
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 typical incubation period for typhoid fever?
1) 1-3 days
2) 4-7 days
3) 10-14 days
4) 21-28 days
General Microbiology Answer: 3The typical incubation period for typhoid fever is 10-14 days: After the ingestion of Salmonella typhi, it typically takes 10-14 days for symptoms to appear. This period can sometimes be shorter or longer, but this is the most common range.
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.
What is the effect of Actinomycin D on orthomyxoviruses?
1) Stimulates multiplication
2) Inhibits multiplication
3) No effect
4) Enhances stability
General Microbiology Answer: 2Actinomycin D is an antibiotic that inhibits RNA synthesis. In the case of orthomyxoviruses, it effectively inhibits their multiplication by preventing the transcription of viral RNA, thereby blocking the virus ability to replicate. Actinomycin D inhibits the multiplication of orthomyxoviruses by blocking RNA synthesis, which is crucial for viral replication.