Name the halogen-containing antiseptic with fungicidal properties, which is used to treat dermatomycosis:

Correct Answer: A

Rationale: Rationale: 1. Iodine solution contains iodine, a halogen with antiseptic properties. 2. Iodine is effective against fungi, making it suitable for treating dermatomycosis. 3. Iodine solution is commonly used in dermatology for its fungicidal properties. 4. Formalin, methylene blue, and brilliant green do not contain halogens or have fungicidal properties. Summary: - Formalin is a disinfectant, not an antiseptic for dermatomycosis. - Methylene blue is an antifungal dye, not used as an antiseptic. - Brilliant green is an antiseptic, but does not contain halogens or have fungicidal properties.

Correct Answer: A

Rationale: Step 1: Gram-positive cocci in chains suggest Streptococcus species. Step 2: Catalase-negative eliminates Staphylococcus aureus. Step 3: Beta-hemolytic on blood agar matches Streptococcus pyogenes. Step 4: Streptococcus pyogenes is a common cause of sore throat (pharyngitis). Summary: A: Streptococcus pyogenes - Correct due to Gram-positive cocci in chains, catalase-negative, beta-hemolytic, and common cause of sore throat. B: Staphylococcus aureus - Incorrect due to catalase-positive. C: Streptococcus pneumoniae - Incorrect due to alpha-hemolytic. D: Enterococcus faecalis - Incorrect due to not being beta-hemolytic.

Correct Answer: A

Rationale: The correct answer is A: Neisseria meningitidis. This is because Neisseria meningitidis is a Gram-negative diplococcus known to cause bacterial meningitis, presenting with fever, headache, and neck stiffness. It is a common cause of meningitis in young adults and teenagers. Streptococcus pneumoniae (B) is a Gram-positive bacteria and a common cause of bacterial pneumonia, not meningitis. Haemophilus influenzae (C) is a Gram-negative coccobacillus that can cause meningitis, but it is less common in adults. Klebsiella pneumoniae (D) is a Gram-negative bacillus known to cause pneumonia and urinary tract infections, not meningitis.

Correct Answer: A

Rationale: The correct answer is A: Mycolic acid in the cell wall. Mycolic acid is a unique component of the cell wall of Mycobacterium species, including the causative agent of tuberculosis. The Ziehl-Neelsen method uses acid-fast staining, where mycolic acid confers resistance to decolorization by acid-alcohol, causing the bacteria to retain the red stain. Choices B, C, and D are incorrect as capsules, flagella, and peptidoglycan layers do not directly contribute to acid-fast staining characteristic of Mycobacterium species.

Correct Answer: B

Rationale: Rationale: The correct answer is B because virulence factors of bacteria are characteristics that enable them to cause disease. Colonization allows bacteria to establish and multiply in the host. Invasion refers to the ability to penetrate host tissues. Toxins are substances produced by bacteria that harm the host. Adhesion is crucial for bacteria to attach to host cells. A: Size and mutation are not typical virulence factors. Resistance is not directly related to causing disease. C: While toxins and evasion of body defenses are correct, motility and size are not universally considered virulence factors. D: Chemotaxis and fermentation are not primary virulence factors, unlike colonization and toxins.

Correct Answer: B

Rationale: The growth of bacteria is a result of water adsorption because water is essential for various metabolic processes within the bacterial cells, such as nutrient uptake, energy production, and waste removal. Water serves as a medium for chemical reactions to occur and provides structural support to the bacteria. Without sufficient water, bacteria cannot thrive and reproduce. A: Air consumption is incorrect because while bacteria may require oxygen for respiration, it is not the primary factor for their growth. C: Enzyme production is incorrect because enzymes are important for various cellular functions but do not directly influence bacterial growth. D: Radio isotopes are incorrect as they are not essential for bacterial growth and can even be harmful to bacterial cells.

Correct Answer: A

Rationale: The correct answer is A: Mycolic acid. Ziehl-Neelsen method is used to stain acid-fast bacteria, such as Mycobacterium species. Mycolic acid in the cell wall of these bacteria resists decolorization, leading to red-colored bacilli on a blue background. Capsule, flagella, and endospores do not play a role in this staining property. Capsules are usually stained using special techniques, flagella are not typically visible with this stain, and endospores are stained using the Schaeffer-Fulton method.

Correct Answer: B

Rationale: The correct answer is B: Precipitins. When a granular sediment forms at the bottom of the test-tubes, it indicates the formation of antigen-antibody complexes that are insoluble and precipitate out of the solution. Precipitins are antibodies that specifically react with antigens to form insoluble complexes. Agglutinins cause clumping of cells, opsonins enhance phagocytosis, and bacteriolysins lyse bacteria. These processes do not result in the formation of a granular sediment, making them incorrect choices in this context.

Correct Answer: A

Rationale: The correct answer is A: Corynebacterium diphtheriae. The presence of rod-shaped bacteria with dark blue polar granules suggests the presence of Corynebacterium diphtheriae, the causative agent of diphtheria. This bacterium is known for causing sore throat and fever, and the characteristic appearance on smear helps identify it. Streptococcus pyogenes (Choice B) typically appears as chains of cocci and is associated with strep throat. Haemophilus influenzae (Choice C) is a small, pleomorphic Gram-negative coccobacillus and is more commonly associated with respiratory infections. Klebsiella pneumoniae (Choice D) is a Gram-negative bacillus and is not typically associated with sore throat and fever in children.