Nokea
Which of the following bacteria is commonly associated with food poisoning?
- A. Salmonella enterica
- B. Clostridium botulinum
- C. Escherichia coli
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D: All of the above. Salmonella enterica, Clostridium botulinum, and Escherichia coli are all commonly associated with food poisoning. Salmonella causes symptoms like diarrhea, vomiting, and abdominal cramps. Clostridium botulinum produces a toxin that leads to symptoms like muscle weakness and paralysis. Escherichia coli can cause symptoms like severe stomach cramps, diarrhea (often bloody), and vomiting. Therefore, all three bacteria are known to cause food poisoning. The other choices are incorrect because each of the bacteria listed is associated with food poisoning.
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A sample stained using Romanovsky-Giemsa method revealed crescent-shaped protozoa with pointed ends and blue cytoplasm. What is the causative agent?
- A. Toxoplasma
- B. Plasmodium
- C. Leishmania
- D. Trypanosoma
Correct Answer: A
Rationale: The correct answer is A: Toxoplasma. The crescent-shaped protozoa with pointed ends and blue cytoplasm described in the question are characteristic of Toxoplasma gondii, the causative agent of toxoplasmosis. Toxoplasma staining with Romanovsky-Giemsa method typically shows these specific morphological features. Plasmodium causes malaria and does not exhibit the described morphology. Leishmania and Trypanosoma are both kinetoplastid parasites, but they do not typically present as crescent-shaped protozoa with blue cytoplasm. Therefore, based on the specific characteristics described in the question, the correct answer is Toxoplasma.
Chlorhexidine:
- A. Is characterised by strong human toxicity
- B. Belongs to the group of alcohols and is widely used for disinfection of surfaces and sanitary facilities
- C. Belongs to the group of biguanides and is widely used for disinfection hands, skin and mucous membranes
- D. Is a disinfectant with limited application
Correct Answer: C
Rationale: Step 1: Chlorhexidine belongs to the group of biguanides, which are commonly used for disinfecting hands, skin, and mucous membranes.
Step 2: It is known to have broad-spectrum antimicrobial activity against various pathogens.
Step 3: The usage of chlorhexidine in healthcare settings for preoperative skin preparation and surgical hand scrub is well-established.
Step 4: The effectiveness and safety profile of chlorhexidine make it a preferred choice for disinfection purposes.
Summary:
- Option A is incorrect as chlorhexidine is not characterized by strong human toxicity.
- Option B is incorrect as chlorhexidine is not classified as an alcohol and is primarily used for disinfecting hands, skin, and mucous membranes.
- Option D is incorrect as chlorhexidine has a wide range of applications in disinfection, especially in healthcare settings.
All statements of viral neutralization reaction are true except:
- A. A key component of the reaction is the complement system involvement
- B. Specific virus neutralising antibodies block the viral ability to infect cells
- C. The antibodies are titrated and two serum samples are required
- D. It is also used to identify newly isolated virus
Correct Answer: A
Rationale: Rationale:
A: Incorrect - The complement system is not directly involved in the viral neutralization reaction.
B: Correct - Specific antibodies neutralize viruses by blocking their ability to infect cells.
C: Incorrect - Antibodies are titrated, but only one serum sample is required for neutralization testing.
D: Incorrect - Viral neutralization is primarily used to measure antibody response, not to identify newly isolated viruses.
A mercury-containing compound used as a preservative in vaccines is:
- A. analgesic
- B. EDTA
- C. codeine
- D. thimerosal
Correct Answer: D
Rationale: The correct answer is D: thimerosal. Thimerosal is a mercury-containing compound used as a preservative in vaccines. It helps prevent contamination and growth of bacteria and fungi in multi-dose vials. Choice A, analgesic, refers to pain relievers, not preservatives. Choice B, EDTA, is a chelating agent used to bind metal ions and is not a preservative. Choice C, codeine, is an opioid pain medication and not a preservative used in vaccines. Thimerosal is the correct answer as it specifically fits the description of a mercury-containing compound used in vaccines.
Humoral factors of the natural resistance are:
- A. Macrophages and macrophages
- B. Lysozyme, lactoferrin, interferon, complement
- C. B and T lymphocytes, NK cells
- D. Immunoglobulins A, G and M
Correct Answer: B
Rationale: The correct answer is B because lysozyme, lactoferrin, interferon, and complement are all humoral factors involved in natural resistance. Lysozyme and lactoferrin are antimicrobial proteins that help defend against pathogens. Interferon is a signaling protein that inhibits viral replication, while complement is a group of proteins that enhance the immune response by promoting inflammation and opsonization.
Choices A, C, and D are incorrect:
- Choice A mentions only macrophages, which are not humoral factors but rather phagocytic cells.
- Choice C lists immune cells involved in adaptive immunity (B and T lymphocytes, NK cells) rather than humoral factors of natural resistance.
- Choice D includes immunoglobulins, which are part of adaptive immunity, not natural resistance.