Nokea
What is the primary purpose of a bacterial capsule?
- A. Protein synthesis
- B. Protection against desiccation
- C. Enhancing virulence by preventing phagocytosis
- D. Facilitating motility
Correct Answer: C
Rationale: The correct answer is C: Enhancing virulence by preventing phagocytosis. Bacterial capsules help bacteria evade the immune system by preventing phagocytosis, a process where immune cells engulf and destroy pathogens. This enhances the bacteria's virulence and ability to cause infections. Choices A, B, and D are incorrect because bacterial capsules do not directly contribute to protein synthesis, protect against desiccation, or facilitate motility.
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The specific prevention (by vaccination) of the disease gas gangrene (caused by Clostridium perfringens) is based on:
- A. Killed whole cell vaccine
- B. Anatoxin
- C. There is no specific prevention by vaccination
- D. Alive attenuated vaccine
Correct Answer: B
Rationale: The correct answer is B: Anatoxin. An anatoxin is a toxin that has been rendered harmless while retaining its ability to stimulate an immune response. Gas gangrene is caused by the toxins produced by Clostridium perfringens, not the bacteria itself. Therefore, vaccination with an anatoxin can trigger the immune system to produce antibodies against the toxin, providing immunity against the disease.
A: Killed whole cell vaccine - Gas gangrene is caused by toxins, not the whole bacterium. This type of vaccine may not be effective in preventing the disease.
C: There is no specific prevention by vaccination - This is incorrect, as vaccination with an anatoxin can prevent gas gangrene.
D: Alive attenuated vaccine - Attenuated vaccines contain live, weakened forms of the pathogen. However, for gas gangrene prevention, targeting the specific toxin with an anatoxin vaccine is more appropriate.
Infections of the CNS can be caused by:
- A. Clostridium botulinum
- B. Morbillivirus morbillorum
- C. Clostridium tetani
- D. All are correct
Correct Answer: D
Rationale: The correct answer is D because all three choices, Clostridium botulinum, Morbillivirus morbillorum, and Clostridium tetani, can cause infections of the CNS. Clostridium botulinum can lead to botulism, affecting the nervous system. Morbillivirus morbillorum can cause measles, which can lead to encephalitis. Clostridium tetani can cause tetanus, affecting the central nervous system. Therefore, all three choices can cause infections of the CNS. Choices A, B, and C are incorrect individually because each pathogen can cause CNS infections.
The type of antibody that can cross the placenta is:
- A. IgA
- B. IgM
- C. IgG
- D. IgD
Correct Answer: C
Rationale: The correct answer is C: IgG. IgG is the only antibody that can cross the placenta due to its small size and unique structure, allowing it to provide passive immunity to the fetus. IgA is mainly found in mucosal secretions, IgM is too large to cross the placental barrier, and IgD plays a role in B cell activation but is not involved in placental transfer.
The following spore-forming bacteria can be preserved in soil over a long period of time: clostridia of tetanus, botulism, anaerobic gas infection. Name the way with which these microorganisms get into soil.
- A. With feces
- B. With urine
- C. With water
- D. With industrial waters
Correct Answer: A
Rationale: Step 1: Clostridia of tetanus, botulism, anaerobic gas infection are spore-forming bacteria.
Step 2: Spores are resistant structures that allow bacteria to survive in harsh conditions.
Step 3: Feces contain these spore-forming bacteria due to contamination.
Step 4: When feces are deposited on soil, the spores of these bacteria enter the soil.
Step 5: Spores can remain dormant in soil for long periods.
Summary: Choice A is correct as spore-forming bacteria enter soil through feces, which act as a source of contamination. Choices B, C, and D are incorrect as they do not involve the direct introduction of spores into soil like feces do.
Acute febrile pharyngitis and pharyngoconjunctival fever are often the clinical presentation of which viral infection:
- A. VZV
- B. Measles virus
- C. Rubella virus
- D. Adenovirus
Correct Answer: D
Rationale: The correct answer is D: Adenovirus. Adenovirus commonly causes acute febrile pharyngitis and pharyngoconjunctival fever. Adenovirus is known to cause respiratory infections and can present with symptoms such as sore throat, fever, and conjunctivitis. VZV (Varicella-Zoster Virus) causes chickenpox and shingles, not these specific symptoms. Measles virus causes a systemic illness with characteristic rash, not typically pharyngitis. Rubella virus causes a mild febrile illness with rash, but not pharyngitis. Therefore, based on the clinical presentation described, adenovirus is the most likely cause.