Nokea
After continuous treatment with antibiotics a patient got symptoms of stomatitis. Examination of specimens of oral mucous membrane revealed some oval polymorphous Gram-positive microorganisms arranged in clusters. What microorganism may be the cause of such manifestations?
- A. С.albicans
- B. C.perfringens
- C. S.aureus
- D. S.pyogenes
Correct Answer: C
Rationale: The correct answer is C: S.aureus. Stomatitis is commonly caused by S.aureus due to its ability to form clusters of oval polymorphous Gram-positive microorganisms. S.aureus is known to colonize the oral mucous membrane and can cause infections, especially after prolonged antibiotic use.
Explanation for other choices:
A: С.albicans - Candida albicans is a fungus commonly associated with oral thrush, not typically causing stomatitis.
B: C.perfringens - Clostridium perfringens is a bacterium associated with food poisoning and gas gangrene, not commonly causing stomatitis.
D: S.pyogenes - Streptococcus pyogenes is known to cause strep throat and skin infections, but not typically associated with stomatitis.
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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.
Which of the following statements for S. Aureus is FALSE
- A. it is always susceptible for penicillin
- B. around its colonies there is a beta hemolytic zone
- C. it produces hemolysins, leucocidins, enterotoxins
- D. has a positive catalase reaction
Correct Answer: A
Rationale: The correct answer is A because Staphylococcus aureus can develop resistance to penicillin over time due to the production of beta-lactamase enzymes. This resistance mechanism makes it no longer susceptible to penicillin. The other choices are correct: B) S. aureus can produce beta hemolysis, C) it produces various toxins like hemolysins, leucocidins, and enterotoxins, and D) it shows a positive catalase reaction due to the presence of catalase enzyme that converts hydrogen peroxide to water and oxygen.
In the micropreparation made from patient's regional lymph node punctate and stained according to Romanovsky-Giemsa method, the doctor found out thin microorganisms with 12-14 equal ringlets and pale- pink sharp pointes 10-13 mkm in length. The pathogen of what disease is it about?
- A. Leishmaniasis
- B. Leptospirosis
- C. Surra
- D. Relapsing fever
Correct Answer: D
Rationale: The thin microorganisms described with 12-14 equal ringlets and pale-pink sharp points are characteristic of Borrelia spirochetes, the causative agent of relapsing fever. The ringlet appearance corresponds to the characteristic coiled structure of Borrelia spirochetes. The length of 10-13 mkm falls within the typical size range of Borrelia spirochetes. This pathogen is commonly identified in Romanovsky-Giemsa stained samples from patients with relapsing fever.
Summary of other choices:
A: Leishmaniasis - Leishmania parasites are larger and do not have the described ringlets or pale-pink sharp points.
B: Leptospirosis - Leptospira bacteria are not described as having ringlets or pale-pink sharp points.
C: Surra - Surra is caused by Trypanosoma evansi, and the description does not match the characteristics of this parasite.
A patient with a sore throat had a throat smear revealing Gram-positive cocci in pairs. The bacteria were catalase-negative and beta-hemolytic. What is the most likely causative agent?
- A. Streptococcus pyogenes
- B. Streptococcus pneumoniae
- C. Enterococcus faecalis
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes.
Rationale:
1. Gram-positive cocci in pairs suggest Streptococcus species.
2. Catalase-negative rules out Staphylococcus.
3. Beta-hemolytic indicates Streptococcus pyogenes due to its beta-hemolytic properties.
Summary:
B: Streptococcus pneumoniae is catalase-negative but not beta-hemolytic.
C: Enterococcus faecalis is not typically beta-hemolytic.
D: Staphylococcus aureus is catalase-positive and not typically in pairs.
Cell mediated immunity has a leading role in:
- A. Infections with facultative and obligate intracellular pathogens
- B. Infections with extracellular pathogens
- C. Type 1 hypersensitivity reactions
- D. Toxin mediated infections
Correct Answer: A
Rationale: Cell-mediated immunity plays a crucial role in combating infections with intracellular pathogens by activating T cells to directly kill infected cells. Facultative and obligate intracellular pathogens, such as viruses and some bacteria, require cell-mediated immunity for effective clearance. Option A is correct due to the specificity of this immune response. Choices B, C, and D are incorrect as they are primarily associated with humoral immunity involving antibodies and not T cell responses against intracellular pathogens.