A chronic localized subcutaneous infection characterized by verrucoid lesions on the skin is:

Correct Answer: D

Rationale: The correct answer is D, chromoblastomycosis. This is a chronic localized subcutaneous infection caused by certain fungi, resulting in verrucoid lesions on the skin. The other choices are incorrect because: A: Candidiasis is a superficial fungal infection, not characterized by verrucoid lesions. B: Leprosy is a systemic bacterial infection, not localized to the skin with verrucoid lesions. C: Shingles is caused by the varicella-zoster virus, presenting as a painful rash with blisters, not verrucoid lesions.

Correct Answer: A

Rationale: The correct answer is A: TRUE. Poxviruses are indeed the largest viruses known, ranging from 200-450 nm in size, which is close to the resolution limit of a light microscope. This makes them almost visible under a light microscope. Explanation: 1. Poxviruses have complex structures and are among the largest viruses. 2. Light microscopes have a resolution limit of around 200 nm. 3. Poxviruses fall within the size range that is close to the resolution limit of a light microscope. 4. Therefore, poxviruses are almost visible under a light microscope. Summary: Choice B is incorrect because poxviruses are indeed large enough to be almost visible under a light microscope. Choice C is incorrect as it implies uncertainty, but poxviruses are consistently close to the resolution limit of a light microscope. Choice D is incorrect as the size of poxviruses being almost visible under a light microscope is a factual statement, not dependent

Correct Answer: A

Rationale: The correct answer is A: infants. Staphylococcal scalded skin syndrome is most common in infants because their immune systems are not fully developed, making them more susceptible to Staphylococcus aureus infections. This bacteria produces exotoxins that cause the skin to blister and peel, characteristic of the syndrome. Adolescents, young adults, and the elderly have more mature immune systems, making them less vulnerable to this specific infection. Therefore, infants are at a higher risk for developing Staphylococcal scalded skin syndrome compared to other age groups.

Correct Answer: A

Rationale: The most probable diagnosis is Tetanus (Choice A) based on the symptoms described. Tetanus is characterized by muscle stiffness, difficulty opening the mouth (trismus), muscle spasms, and convulsions. The progression of symptoms from muscle tension to generalized convulsions every 10-15 min is classic for tetanus. Tetania (Choice B) is similar but typically presents with more subtle muscle contractions rather than convulsions. Meningoencephalitis (Choice C) presents with fever, headache, and altered mental status, not the muscle symptoms described. Hemorrhagic stroke (Choice D) presents with sudden onset neurological deficits like weakness or sensory changes, not the muscle symptoms described.

Correct Answer: A

Rationale: The correct answer is A: Corynebacterium diphtheriae. This bacterium causes diphtheria, characterized by a grayish pseudomembrane in the throat. The dark blue-staining rods with polar granules seen in microscopic examination are known as metachromatic granules, which are specific to Corynebacterium diphtheriae. Streptococcus pyogenes (choice B) causes strep throat but does not produce pseudomembranes. Haemophilus influenzae (choice C) can cause respiratory infections but does not typically present with a pseudomembrane. Neisseria gonorrhoeae (choice D) is a sexually transmitted bacterium and is not associated with the symptoms described.

Correct Answer: A

Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas is a Gram-negative rod, oxidase-positive, and a lactose non-fermenter. The presence of fever and chills suggests a systemic infection, which is common with Pseudomonas. Salmonella typhi, Shigella dysenteriae, and Escherimalia coli are all Gram-negative rods but are typically lactose fermenters and do not match the characteristics described in the question.

Correct Answer: C

Rationale: The correct answer is C: To perform serodiagnostics of tuberculosis. Rationale: The negative reaction to the Mantoux test indicates absence of TB infection. Performing serodiagnostics will further confirm the absence of active infection. This is important to rule out TB before considering vaccination or isolation measures. Summary: A: BCG vaccination is not necessary as the boy shows a negative reaction to the Mantoux test. B: Repeating the test in a month is unnecessary as the initial test already showed a negative reaction. D: Isolating the boy is not warranted as there is no evidence of active TB infection.

Correct Answer: A

Rationale: The correct answer is A: Sabouraud. Sabouraud agar is specifically designed to promote the growth of fungi due to its low pH and high glucose content. The cream-like colonies indicate fungal growth, as fungi often appear as fluffy or powdery colonies on Sabouraud agar. Lowenstein-Jensen is used for mycobacteria, Roux for diphtheria, and Loeffler for Corynebacterium diphtheriae. Therefore, Sabouraud is the most suitable medium for detecting fungal contamination based on the characteristics of the colonies formed.

Correct Answer: A

Rationale: The correct answer is A: Escherichia coli. E. coli is the most common bacteria responsible for causing urinary tract infections due to its ability to adhere to the urinary tract lining and multiply rapidly. It is a normal inhabitant of the gut and can enter the urinary tract through improper hygiene practices. Salmonella enterica and Neisseria gonorrhoeae are typically associated with other infections like food poisoning and gonorrhea, respectively. Mycobacterium tuberculosis causes tuberculosis, not urinary tract infections. Thus, based on its prevalence and pathogenicity in the urinary tract, E. coli is the correct choice.