Correct Answer: D

Rationale: The correct answer is D: Hyaluronidase synthesis. Hyaluronidase is an enzyme produced by some pathogens to break down hyaluronic acid in the extracellular matrix, aiding their spread. This action does not directly counteract the immune system's mechanisms. Antigenic heterogeneity and mimicry can evade immune recognition. IgA proteases degrade IgA antibodies, impairing mucosal immunity. Therefore, D is the only choice not directly involved in counteracting the immune system.

Correct Answer: B

Rationale: Rationale: 1. The patient has symptoms of fever, enlarged lymph nodes, red and tender skin, which are indicative of systemic infection. 2. The inguinal lymph nodes in plague become enlarged, tender, and painful, forming buboes. 3. The presence of acute serohemorrhagic inflammation in the lymph node is characteristic of plague. 4. Plague is a zoonotic bacterial infection caused by Yersinia pestis, commonly transmitted through fleas from rodents. 5. Brucellosis, anthrax, and tularemia do not typically present with inguinal lymph node involvement and acute serohemorrhagic inflammation. Summary: - Brucellosis: Usually presents with flu-like symptoms, joint pain, and fever, not inguinal lymph node enlargement. - Anthrax: Presents with skin lesions, respiratory symptoms, or gastrointestinal symptoms, not inguinal lymph node involvement. - Tularemia: Presents with fever, skin ulcers,

Correct Answer: C

Rationale: The correct answer is C because bacteriocins are substances with protein nature, not polysaccharides. Bacteriocins are antimicrobial peptides that kill bacterial cells, mainly those of closely related species or other strains of the same species. Polysaccharides are not typically involved in bacteriocin activity. Therefore, option C is false. Options A, B, and D are true statements supported by the nature and function of bacteriocins.

Correct Answer: A

Rationale: The correct answer is A: Entamoeba gingivalis. Firstly, it is important to note that Entamoeba gingivalis is commonly found in the oral cavity, specifically in carious cavities. Secondly, Entamoeba gingivalis belongs to the Sarcodina class, which is characterized by their amoeboid movement using pseudopods. This protozoa is associated with oral health issues, particularly in individuals with poor oral hygiene. Now, let's analyze why the other choices are incorrect: B: Entamoeba histolutica is known for causing amoebic dysentery, not commonly associated with oral cavities. C: Entamoeba coli is typically found in the human large intestine, not in oral cavities. D: Amoeba proteus is a free-living amoeba commonly used in laboratory studies and not typically associated with oral cavity infections.

Correct Answer: A

Rationale: The correct answer is A: Actinomycosis. This is supported by the presence of purulent foci with druses consisting of short rod-like elements attached to a homogenous center, which is characteristic of Actinomyces species. Actinomycosis commonly presents with granulation tissue and connective tissue formation. B: Tuberculosis does not typically present with druses containing short rod-like elements. C: Syphilis does not typically present with purulent foci or druses. D: Candidosis does not typically present with the described features of purulent fluxing and druses with short rod-like elements.