Which one is an example of an immunomodulator

Correct Answer: C

Rationale: Step-by-step rationale for why C is correct: 1. Immunomodulators regulate the immune response. 2. Gamma-interferon is a cytokine that enhances immune function. 3. It helps fight infections and regulate inflammation. 4. Pentaxim and Hexacima are combination vaccines. 5. Rifampin is an antibiotic, not an immunomodulator. Summary: - A and B are combination vaccines. - D is an antibiotic. - C is the correct answer as gamma-interferon is an immunomodulator that regulates the immune response.

Correct Answer: A

Rationale: The correct answer is A: Candida fungi. In the context of a 70-year-old man with angular cheilitis (lesion at the corners of the mouth) and stomatitis, the presence of large ovoid gram-positive cells points towards Candida species, which are yeast fungi. Candida is a common opportunistic pathogen that can cause oral thrush and angular cheilitis in immunocompromised individuals, such as elderly people. Candida fungi are known to appear as large ovoid cells under microscopic examination. Summary of other choices: B: Streptococci are gram-positive bacteria and are not typically associated with large ovoid cells seen in this case. C: Staphylococci are also gram-positive bacteria and are not known to present as large ovoid cells in this context. D: Neisseria are gram-negative bacteria and are not the usual etiological agents for oral lesions like angular cheilitis.

Correct Answer: A

Rationale: The correct answer is A: Acid-fast stain. This stain is used for diagnosing tuberculosis due to the unique cell wall composition of Mycobacterium tuberculosis, which resists decolorization by acid-alcohol. This allows the bacteria to retain the primary stain (carbol fuchsin) and appear red under a microscope. Gram stain (B) is not suitable for Mycobacterium tuberculosis as it is gram-positive but does not retain the crystal violet-iodine complex. Negative stain (C) is not used for bacterial identification. Simple stain (D) does not differentiate acid-fast bacteria like Mycobacterium tuberculosis.

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.

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.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Tularemia is caused by Francisella tularensis, a highly infectious bacterium. 2. Francisella tularensis is the only pathogen specifically known to cause tularemia. 3. The other choices (Bordetella pertussis, Brucella suis, Legionella sp.) are not associated with tularemia. 4. Therefore, the correct answer is A - Francisella tularensis.

Correct Answer: D

Rationale: Interferon is a cell-specific protein that is produced and released from infected cells in response to viral infections. It acts extracellularly to interfere with viral replication, not to inactivate the virus itself. Interferon is not coded for by cellular DNA, but by viral RNA during infection. Therefore, the correct answer, D, is that interferon is not virus-specific but is cell-specific. This is because interferon can be produced by various cell types in response to different types of viral infections, making it a broad-spectrum antiviral defense mechanism.

Correct Answer: B

Rationale: The correct answer is B: Ethambutol. Ethambutol is known to cause optic neuritis, affecting the visual nerve. It is a well-documented side effect of this drug. Isoniazid (Choice A) is associated with peripheral neuropathy, not optic neuritis. Kanamycin (Choice C) is known for its side effects on the inner ear, causing hearing loss. Rifampicin (Choice D) is not typically associated with optic neuritis but can cause other adverse effects like hepatitis. By process of elimination and knowledge of drug side effects, Ethambutol is the most likely culprit.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas. Pseudomonas bacteria are known to produce yellow-green pigment and a characteristic odor, specifically in meat-peptone agar. This is due to the production of pyoverdin pigment by Pseudomonas. Other choices like Escherichia, Proteus, Klebsiella, and Azotobacter do not typically produce yellow-green pigment or have a characteristic odor in meat-peptone agar. Therefore, based on the specific characteristics mentioned in the question, Pseudomonas is the most appropriate choice.