Nokea
Which enzyme is one of the most important and constant criteria for pathogenicity of staphylococcus aureus?
- A. beta lactamase
- B. plasma coagulase
- C. catalase
- D. None of the above
Correct Answer: B
Rationale: The correct answer is B: plasma coagulase. This enzyme is essential for the pathogenicity of Staphylococcus aureus as it can convert fibrinogen to fibrin, forming a protective barrier around the bacteria. This helps the bacteria evade the host's immune system. Beta lactamase (A) is not directly related to pathogenicity but rather resistance to beta-lactam antibiotics. Catalase (C) is produced by many bacteria, including Staphylococcus aureus, but it is not a specific indicator of pathogenicity. Choice D is incorrect as plasma coagulase is indeed an important criterion for the pathogenicity of Staphylococcus aureus.
You may also like to solve these questions
Viruses that are mainly transmitted through sexual contact are:
- A. Arenaviruses
- B. Togaviruses
- C. Papillomaviruses
- D. Polyomaviruses
Correct Answer: C
Rationale: The correct answer is C: Papillomaviruses. Papillomaviruses are primarily transmitted through sexual contact, as they infect the skin and mucous membranes of the genital area. This transmission route is well-documented through research and epidemiological studies. Arenaviruses (A) are primarily transmitted through contact with infected rodents, not sexual contact. Togaviruses (B) are mainly transmitted by mosquitoes and ticks. Polyomaviruses (D) are typically spread through respiratory secretions or contaminated urine, not through sexual contact. Therefore, the most appropriate choice for viruses transmitted mainly through sexual contact is Papillomaviruses (C).
Which of these viruses is a laboratory product?
- A. Monkeypox
- B. Variola
- C. Vaccinia
- D. Cowpox
Correct Answer: C
Rationale: Rationale:
1. Vaccinia is a laboratory product used in smallpox vaccination.
2. Variola is the virus that causes smallpox, not a laboratory product.
3. Monkeypox is a naturally occurring virus, not a laboratory product.
4. Cowpox can be found in nature and is used in vaccine production, but it is not a laboratory product like Vaccinia.
Virulence
- A. Is the degree of pathogenicity
- B. Of the microorganism is not a constant characteristic
- C. Can be measured with LD50
- D. All the answers are true
Correct Answer: D
Rationale: The correct answer is D because virulence refers to the degree of pathogenicity of a microorganism, which can vary and is not a constant characteristic. It can be measured using LD50, which is the lethal dose that kills 50% of the test population. Therefore, all the statements in options A, B, and C are true and collectively provide a comprehensive understanding of virulence.
A duodenal content smear of a patient with indigestion contains protozoa 10-18 mcm large. They have piriform bodies, 4 pairs of filaments, two symmetrically located nuclei in the broadened part of body. What kind of the lowest organisms is it?
- A. Lamblia
- B. Dysentery ameba
- C. Trichomonas
- D. Intestinal ameba
Correct Answer: A
Rationale: The correct answer is A: Lamblia. The description matches the characteristics of Giardia lamblia - a protozoan parasite that causes giardiasis. The piriform bodies, 4 pairs of filaments, and two symmetrically located nuclei are specific to Giardia lamblia. It is important to differentiate it from the other choices. Dysentery ameba (choice B) typically has a single nucleus and lacks the specific characteristics described. Trichomonas (choice C) is a flagellated protozoan with different morphology and does not match the given description. Intestinal ameba (choice D) such as Entamoeba histolytica usually has a single nucleus and different body shape compared to the described organism.
Allergies to sea food, eggs, etc are an example of:
- A. Type 1 hypersensitivity reaction
- B. Type 2 hypersensitivity reaction
- C. Type 3 hypersensitivity reaction
- D. Type 4 hypersensitivity reaction
Correct Answer: A
Rationale: The correct answer is A: Type 1 hypersensitivity reaction. In this type of reaction, allergens trigger the production of IgE antibodies, leading to mast cell and basophil degranulation and release of inflammatory mediators like histamine. This causes immediate allergic symptoms. Seafood and eggs are common allergens that can elicit this response.
B: Type 2 hypersensitivity reaction involves antibodies targeting cell surface or extracellular matrix antigens, leading to cell destruction or dysfunction. This is not the mechanism in seafood or egg allergies.
C: Type 3 hypersensitivity reaction involves immune complex deposition in tissues, leading to inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.
D: Type 4 hypersensitivity reaction is cell-mediated and involves T cells causing inflammation and tissue damage. This is not the mechanism in seafood or egg allergies.