Nokea
Microscopic examination of a patient's lymph node revealed thin, pale pink microorganisms with 12-14 uniform spiral coils stained by Romanovsky-Giemsa method. What disease is caused by this microorganism?
- A. Syphilis
- B. Leptospirosis
- C. Relapsing fever
- D. Trypanosomiasis
Correct Answer: A
Rationale: Rationale:
1. Thin, pale pink microorganisms with spiral coils suggest Treponema pallidum, the causative agent of syphilis.
2. Staining with Romanovsky-Giemsa method highlights the characteristic morphology of T. pallidum.
3. Syphilis presents with various stages and symptoms, correlating with the lymph node involvement.
4. Leptospirosis is caused by Leptospira interrogans, presenting with different clinical features.
5. Relapsing fever is caused by Borrelia species, which do not match the description.
6. Trypanosomiasis is caused by Trypanosoma species, which have distinct morphology and staining properties.
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During fibergastroscopy a patient with ulcer disease of the stomach, the mucosal biopsy is taken from the area of an ulcer. Impression smear is prepared from biopsy material and stained by Gram method; the rest of biopsy material is tested for urease activity. Microscopy of the impression smear revealed gram- negative spiral-shaped microorganisms, urease activity test is positive. What bacteria were detected?
- A. Helicobacter pylori
- B. Campilobacter jejuni
- C. Treponema pallidum
- D. Spirilla minor
Correct Answer: A
Rationale: The correct answer is A: Helicobacter pylori.
Rationale:
1. Gram-negative spiral-shaped microorganisms match the morphology of Helicobacter pylori.
2. Positive urease activity is a characteristic feature of Helicjsonacter pylori.
3. Helicobacter pylori is specifically associated with gastric ulcers and is a common pathogen in the gastrointestinal tract.
Summary:
Choice B, Campilobacter jejuni, is a gram-negative curved bacterium but is not typically associated with gastric ulcers or urease activity. Choice C, Treponema pallidum, is a spirochete bacterium causing syphilis, which is not related to gastric ulcers. Choice D, Spirilla minor, is a generic term for spiral-shaped bacteria and is not a specific pathogen associated with gastric ulcers or urease activity.
A 10-year-old child cut his leg with a glass shard, when playing, and was delivered to outpatient department to receive anti-tetanus serum. To prevent development of anaphylactic shock the serum was introduced by Bezredka method. This method of organism hyposensitization is based on the following mechanism:
- A. Stimulation of antigen-specific IgG2
- B. Stimulation of the immunological antigen tolerance
- C. Binding of mast cell-fixed IgE
- D. Blocking of mast cell mediators synthesis
Correct Answer: C
Rationale: The correct answer is C: Binding of mast cell-fixed IgE. The Bezredka method involves introducing small amounts of the antigen to which the individual is allergic, leading to the binding of mast cell-fixed IgE. This process desensitizes the immune system and prevents anaphylactic shock by reducing the release of histamine and other mediators from mast cells.
Rationale:
1. A: Stimulation of antigen-specific IgG2 is incorrect because the Bezredka method primarily targets IgE, not IgG2.
2. B: Stimulation of the immunological antigen tolerance is incorrect as this method aims to block the allergic response rather than induce tolerance.
3. D: Blocking of mast cell mediators synthesis is incorrect because the Bezredka method does not directly inhibit the synthesis of mast cell mediators, but rather blocks their release by binding IgE.
Which bacteria are known for their ability to survive in extreme heat?
- A. Psychrophiles
- B. Mesophiles
- C. Thermophiles
- D. Halophiles
Correct Answer: C
Rationale: The correct answer is C: Thermophiles. Thermophiles are bacteria that thrive in high temperatures typically above 45°C. They have specialized enzymes and cellular structures that allow them to survive and even thrive in extreme heat. Psychrophiles (A) are adapted to cold temperatures, mesophiles (B) thrive at moderate temperatures, and halophiles (D) prefer high salt concentrations, making them unsuitable for extreme heat survival. Therefore, Thermophiles are the only bacteria among the choices that are known for their ability to survive in extreme heat.
A patient with a sore throat had a throat smear revealing Gram-positive cocci in pairs with a capsule. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Neisseria meningitidis
- C. Haemophilus influenzae
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: Rationale:
1. Gram-positive cocci in pairs indicate Streptococcus pneumoniae.
2. Presence of a capsule points to S. pneumoniae as it has a polysaccharide capsule.
3. S. pneumoniae commonly causes sore throat.
4. Neisseria meningitidis, Haemophilus influenzae, and Klebsiella pneumoniae are not typically associated with sore throat.
Which of the following bacteria is associated with the formation of dental caries?
- A. Streptococcus mutans
- B. Streptococcus pneumoniae
- C. Bacillus cereus
- D. Clostridium tetani
Correct Answer: A
Rationale: Step 1: Streptococcus mutans is known for its ability to produce lactic acid, which contributes to the demineralization of tooth enamel, leading to dental caries.
Step 2: Streptococcus pneumoniae is a common respiratory pathogen and not directly associated with dental caries.
Step 3: Bacillus cereus is a foodborne pathogen and not typically found in the oral cavity or associated with dental caries.
Step 4: Clostridium tetani causes tetanus, a neurological condition, and is not involved in the formation of dental caries.
Summary: Choice A is correct as Streptococcus mutans is specifically linked to dental caries due to its acidogenic and aciduric properties. Choices B, C, and D are incorrect as they are not associated with dental caries.