A 40-year-old man developed skin redness and an swelling in the neck area, where eventually a small abscess appeared. The section the focus is dense and yellow-green colored. In the purulent masses there are white granules. Histologically there are fungal druses, plasma and xanthome cells, and macrophages detected. Specify the most correct etiological name of this pathological process?

Correct Answer: A

Rationale: The correct answer is A: Actinomycosis. This is a chronic bacterial infection caused by Actinomyces species. In this case, the description of dense yellow-green colored focus, white granules in purulent masses, and presence of fungal druses, plasma cells, xanthome cells, and macrophages all match the characteristics of actinomycosis. Actinomycosis typically presents with abscess formation containing sulfur granules, which are yellowish and granular. The other choices (B: Furuncle, C: Carbuncle, D: Syphilis) do not fit the clinical and histological features described in the question, making them incorrect options.

Correct Answer: B

Rationale: The correct answer is B because in immune reactions, a large lattice is formed when antigens and antibodies are in optimal proportion. This optimal ratio allows for the formation of a strong antigen-antibody complex, leading to the aggregation of immune complexes into large lattice structures. When antibodies are in excess (choice A), there may not be enough antigens to form a stable lattice. Similarly, when antigens are in excess (choice C), there may be insufficient antibodies to form a strong lattice. Choice D is incorrect because the optimal proportion of antigens and antibodies is crucial for the formation of large lattices in immune reactions.

Correct Answer: A

Rationale: The correct answer is A: Actinomycosis. This is a chronic bacterial infection caused by Actinomyces species. In this case, the description of dense yellow-green colored focus, white granules in purulent masses, and presence of fungal druses, plasma cells, xanthome cells, and macrophages all match the characteristics of actinomycosis. Actinomycosis typically presents with abscess formation containing sulfur granules, which are yellowish and granular. The other choices (B: Furuncle, C: Carbuncle, D: Syphilis) do not fit the clinical and histological features described in the question, making them incorrect options.

Correct Answer: A

Rationale: The correct answer is A: Nystatin. Nystatin is specifically used to treat intestinal candidiasis because it targets and eliminates the Candida species responsible for the infection. It is not absorbed systemically, acting only locally in the gastrointestinal tract. Griseofulvin (B) is mainly used to treat fungal skin infections, not intestinal candidiasis. Undecyne (C) is an antifungal agent used for skin infections, not for intestinal candidiasis. Amphotericin B (D) is a potent antifungal agent used for systemic fungal infections, not specifically for intestinal candidiasis.

Correct Answer: B

Rationale: The correct answer is B: lipopolysaccharides. Endotoxins are part of the outer membrane of Gram-negative bacteria, consisting of lipid A, core polysaccharides, and O antigen. Lipopolysaccharides are known to induce strong immune responses and can cause septic shock. Proteins (choice A) are components of exotoxins, not endotoxins. Teichoic acid (choice C) is found in Gram-positive bacteria, not Gram-negative bacteria. Peptidoglycan (choice D) is a major component of bacterial cell walls but is not considered an endotoxin.

Correct Answer: C

Rationale: The correct answer is C: E + S = P. This notation represents the interaction between an enzyme (E) and a substrate (S) resulting in a product (P). Enzymes facilitate chemical reactions by binding to substrates and converting them into products. Choice A is incorrect because it does not include the enzyme in the reaction. Choice B is incorrect as it involves two substrates binding to the enzyme, not a substrate converting to a product. Choice D is incorrect as it shows two substrates reacting to form a product without involvement of an enzyme. Thus, choice C accurately represents the process of enzymatic reactions involving enzymes, substrates, and products.

Correct Answer: C

Rationale: Plasmids often carry antibiotic resistance genes, making choice C correct. Plasmids are circular DNA structures, not linear (A). They are found in both gram-positive and gram-negative bacteria, not exclusively in gram-positive bacteria (B). Plasmids are separate from the bacterial chromosome, not part of it (D). Therefore, choice C is the correct answer.

Correct Answer: D

Rationale: The correct answer is D: complex. Bacteriophages are considered complex viruses because they have a complex structure consisting of a polyhedral head, a helical tail, and tail fibers. The head contains the viral genetic material, while the tail facilitates attachment to the host bacterial cell. This complexity distinguishes bacteriophages from simpler viruses like helical and icosahedral viruses. Helical viruses have a rod-like shape, while icosahedral viruses have a symmetrical, 20-sided structure. Enveloped viruses have a lipid bilayer envelope surrounding their capsid, which bacteriophages lack. Therefore, the unique and intricate structure of bacteriophages classifies them as complex viruses.

Correct Answer: B

Rationale: The correct answer is B: colonization. E. Coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa in the pharynx indicate colonization rather than being part of the normal resident flora. Colonization refers to the presence of these bacteria on body surfaces without causing harm. They are not considered normal flora in the pharynx but rather transient or opportunistic pathogens. Choice A is incorrect because these bacteria are not part of the normal resident flora of the pharynx. Choice C is incorrect as it implies that these bacteria are both normal flora and colonization, which is not accurate. Choice D is incorrect as there is evidence of bacterial presence, indicating colonization.