MDS PREP
Which of the following is a method for indirect diagnosis of tuberculosis?
1) Culture methods
2) Smear examination
3) Polymerase chain reaction
4) Latex agglutination
General Microbiology Answer: 4The polymerase chain reaction (PCR) is a molecular technique used to amplify DNA sequences. In the context of tuberculosis, PCR can be used to detect the presence of Mycobacterium tuberculosis DNA in clinical samples, making it a valuable tool for indirect diagnosis.
What are the typical clinical features of typhoid fever?
1) High fever, bradycardia, and a palpable spleen
2) Rash, joint pain, and respiratory symptoms
3) Diarrhea, abdominal cramps, and vomiting
4) Headache, photophobia, and neck stiffness
General Microbiology Answer: 1The typical clinical features of typhoid fever can be listed as follows:
1. High fever, bradycardia, and a palpable spleen: Typhoid fever is
characterized by a sustained high fever, often reaching 103°F to 104°F (39°C to
40°C). Bradycardia, or a slower than normal heart rate, occurs in some cases.
The spleen may also become enlarged and palpable due to the infection.
2. Rash, joint pain, and respiratory symptoms: Some patients may develop a rash
known as "Rose spots," which are small, red spots on the abdomen and chest.
Joint pain can occur, and respiratory symptoms may include a dry cough.
3. Diarrhea, abdominal cramps, and vomiting: Diarrhea and severe abdominal
cramps are common in the early stages of typhoid fever, which can lead to
significant dehydration and discomfort for the patient.
4. Headache, photophobia, and neck stiffness: Headaches and sensitivity to light
(photophobia) are often present, and in severe cases, neck stiffness can occur
due to inflammation of the meninges, known as meningitis.
The term cold sterilization has been employed to refer to
1. physical methods of sterilization
2. prolonged exposure to 20° C
3. exposure to low temperature steam
4. chemical disinfection
Microbiology
Answer: 4
chemical disinfection is cold strelization
What is the primary mode of action of exotoxins?
1) Enzymatic
2) Non-enzymatic
3) Structural disruption
4) Inhibition of protein synthesis
General Microbiology Answer: 1
The primary mode of action of exotoxins is enzymatic, as they often act as enzymes that modify or damage host cell functions.
What is the size range of adenoviruses?
1) 50-100 nm
2) 70-75 nm
3) 100-150 nm
4) 200-300 nm
General Microbiology Answer: 2Adenoviruses are medium-sized viruses that typically range from 70 to 90 nanometers in diameter, with the most common size being around 70-75 nm. They are known for causing respiratory infections and conjunctivitis
What is the typical macroscopic appearance of the stool in cases of amoebic dysentery compared to bacillary dysentery?
1) Amoebic dysentery stool is small and odorless, while bacillary dysentery stool is copious and offensive.
2) Both amoebic and bacillary dysentery stools are copious and offensive.
3) Amoebic dysentery stool is dark red and acidic, while bacillary dysentery stool is bright red and alkaline.
4) Amoebic dysentery stool is bright red and alkaline, while bacillary dysentery stool is dark red and acidic.
Amoebic dysentery stool is typically dark red and acidic, while bacillary dysentery stool is bright red and alkaline.
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
Which of the following is NOT a method used to produce a recombinant hepatitis B vaccine?
1) Cloning the HBsAg gene in E. coli
2) Cloning the HBsAg gene in yeasts Saccharomyces cerevisae
3) Extracting and purifying HBsAg particles from infected human plasma
4) Using baculovirus vectors to produce HBsAg in insect cells
General Microbiology Answer: 1
While recombinant hepatitis B vaccines are produced using various methods, cloning the HBsAg gene in E. coli is not one of them. Instead, the gene is typically cloned in yeast or insect cells to produce the surface antigen for the vaccine.