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
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
Which of the following is a characteristic of endotoxins that makes them distinct from exotoxins?
1) They are heat labile
2) They are actively secreted by bacterial cells
3) They are proteins
4) They are part of the bacterial cell wall
General Microbiology Answer: 4
Endotoxins are components of the outer membrane of Gram-negative bacteria and are released when the bacteria die or divide. This structural characteristic differentiates them from exotoxins, which are secreted by living bacteria.
What is the primary reservoir for prions?
1) Bacteria
2) Viruses
3) Proteinaceous particles
4) Nucleic acids
General Microbiology Answer: 3Prions are infectious agents composed solely of protein. They do not have nucleic acids like DNA or RNA and are responsible for several neurodegenerative diseases. The primary reservoir for prions is thus the proteinaceous particles themselves.
The destruction of microorganisms on living tissues, as long as there is contact between the tissues and the antimicrobial agent, denotes
1. sterilization
2. antisepsis
3. sanitization
4. none of the above
Microbiology
Answer: 2
The destruction of microorganisms on living tissues, as long as there is contact between the tissues and the antimicrobial agent, denotes antisepsis (option 2). Antisepsis refers to the application of antimicrobial agents to living tissues to reduce the possibility of infection, sepsis, or putrefaction.
Sterilization:
This is the process of completely eliminating all forms of microbial
life, including bacteria, viruses, fungi, and spores, from an object or
surface. Sterilization is typically achieved through methods such as
autoclaving (steam under pressure), dry heat, chemical sterilants, or
radiation. Sterilization is used for medical instruments, laboratory
equipment, and other items that must be free of all microorganisms.
Antisepsis:
Antisepsis refers to the application of antimicrobial agents to
living tissues to reduce the risk of infection, sepsis, or putrefaction.
Antiseptics are used on skin and mucous membranes to prevent infection
during surgical procedures, wound care, and other medical interventions.
Common antiseptics include alcohol, iodine solutions, and chlorhexidine.
Sanitization:
Sanitization is the process of reducing the number of microorganisms
on surfaces or objects to a level considered safe by public health
standards. This does not necessarily eliminate all microorganisms but
reduces them to a level that minimizes the risk of infection or disease.
Sanitization is commonly used in food service, public restrooms, and
other environments where hygiene is important.
The minimum and maximum temperature for normal metabolic
activity microorganisms that live on or within the human body is
1 50 C
to 300 C
2 200 C to 450
C
3. 300 C to 400
C
4. 15 C to 600
C
Microbiology Answer: 2
The minimum and maximum temperature for normal metabolic activity microorganisms that live on or within the human body is 20° C to 45°C
What is the recommended storage condition for both recombinant and plasma-derived hepatitis B vaccines?
1) At room temperature
2) In a refrigerator
3) In a freezer
4) At 4°C to 8°C
General Microbiology Answer: 4
oth recombinant and plasma-derived hepatitis B vaccines should be stored at temperatures between 4°C and 8°C to maintain their efficacy and stability. Proper storage is crucial to ensure the vaccines remain effective when administered.
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.