MDS PREP
The main tool for detection of "cases" of tuberculosis is -
1. Sputum examination
2. Mantoux test
3. Chest X-ray
4. All of the above
Microbiology
Answer: 1
The main tool for the detection of "cases" of tuberculosis is 1.
Sputum examination.
Explanation of Each Option:
Sputum examination: This is the primary method for
diagnosing active pulmonary tuberculosis. Sputum samples are collected and
examined for the presence of Mycobacterium tuberculosis through
microscopy (e.g., acid-fast bacilli staining) and culture methods. It is
considered the gold standard for confirming active TB cases.
Mantoux test: Also known as the tuberculin skin test,
this test is used to determine if a person has been exposed to the
tuberculosis bacteria. However, it does not diagnose active TB; rather, it
indicates whether a person has been infected with the bacteria at some
point.
Chest X-ray: While chest X-rays are important for
identifying lung abnormalities associated with tuberculosis and can support
the diagnosis, they are not definitive for detecting the bacteria itself.
They are often used in conjunction with sputum examination.
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.
What is the primary characteristic of prions?
1) They contain nucleic acid.
2) They are sensitive to heat.
3) They are resistant to proteases.
4) They are proteinaceous infectious particles.
General Microbiology Answer: 4Prions are infectious proteins that are highly resistant to destruction by proteases and other methods that typically degrade proteins. This resistance is what allows them to persist in the host and cause disease. They do not contain nucleic acid, which is a hallmark of other types of infectious agents such as bacteria, viruses, and fungi.
Which of the following statements about the fermentation of sugars by Anthracoid bacilli is true?
1) Anthracoid bacilli ferment glucose, maltose, lactose, and sucrose, producing acid and gas.
2). Anthracoid bacilli do not ferment glucose but ferment maltose, lactose, and sucrose.
3) Anthracoid bacilli only ferment glucose.
4) Anthracoid bacilli ferment glucose, maltose, and lactose, but not sucrose.
General Microbiology Answer: 1
Anthracoid bacilli, such as those in the genus Bacillus, are capable of fermenting various sugars, including glucose, maltose, lactose, and sucrose. This fermentation process results in the production of acid and gas, which can be detected by observing changes in the pH of the medium and the formation of gas bubbles. This statement is true as it accurately describes the typical sugar fermentation profile of these bacteria.
Which of the following is the correct Lancefield group for Streptococcus pyogenes?
1) A
2) B
3) C
4) D
Streptococcus pyogenes is classified as Lancefield group A.
Which of the following describes the colony morphology of Bacillus anthracis on an agar plate?
1) Smooth and shiny
2) Irregularly round with a frosted glass appearance
3) Small and translucent
4) Large and mucoid
Bacillus anthracis colonies on an agar plate typically appear irregularly round with a frosted glass appearance.
Which of the following is a distinguishing feature of orthomyxoviruses?
1) Single linear RNA
2) 80-120 nm in size
3) Hemolysin present
4) Cytoplasmic replication
General Microbiology Answer: 2Orthomyxoviruses, which include the influenza viruses, are characterized by their single-stranded RNA genome. This feature distinguishes them from other virus families that may have different types of genetic material. Orthomyxoviruses are distinguished by their single linear RNA genome, which is essential for their replication and pathogenicity.
What is the primary target of antibodies in neutralizing the action of exotoxins?
1) Cell wall components
2) Lipopolysaccharides
3) Protein components of the toxin
4) Enzymes involved in toxin production
General Microbiology Answer: 3
Antibodies neutralize exotoxins by binding to their protein components, preventing them from interacting with host cells and causing damage. This immune response is critical for protecting the host from the harmful effects of these toxins.