A child is presumably ill with diphtheria. A specimen of affected mucous membrane of his pharynx was taken for analysis. The smear was stained and microscopic examination revealed yellow rods with dark blue thickenings on their ends. What structural element of a germ cell was revealed in the detected microorganisms?

Correct Answer: A

Rationale: The correct answer is A: Volutin granules. Volutin granules are metachromatic granules that stain dark blue with methylene blue or Leishman stain. In diphtheria-causing bacteria, Corynebacterium diphtheriae, these granules are typically seen as yellow rods with dark blue thickenings on their ends when stained. Volutin granules are storage inclusions composed of polymetaphosphate that serve as an energy reserve for the bacteria. The presence of these granules in the detected microorganisms indicates the characteristic feature of Corynebacterium diphtheriae. Summary of other choices: B: Plasmids are extrachromosomal DNA molecules that are not typically visible on stained smears. C: Capsules are outer protective layers that are not visible on stained smears. D: Spores are reproductive structures formed by certain bacteria, not typically seen in Corynebacterium diphtheriae.

Correct Answer: A

Rationale: The correct answer is A: Anthrax. The symptoms of fever, headache, weakness, and the skin lesion described (hyperemic with a dark red infiltration, black center, and pustules) are characteristic of cutaneous anthrax. The black center is known as an eschar. Anthrax is caused by the bacterium Bacillus anthracis, commonly found in cattle. Plague (choice B) typically presents with swollen lymph nodes (buboes) and is caused by Yersinia pestis. Tularemia (choice C) presents with fever, ulcer at the site of infection, and lymphadenopathy, caused by Francisella tularensis. Furuncle (choice D) is a localized skin infection typically caused by Staphylococcus aureus, presenting as a red, swollen, and painful bump.

Correct Answer: C

Rationale: Step-by-step rationale: 1. The Filoviridae family includes Marburg virus and Ebola virus. 2. Both viruses are characterized by filamentous, enveloped structure. 3. They cause severe hemorrhagic fever in humans. 4. Lassa virus and lymphocytic choriomeningitis viruses belong to Arenaviridae. 5. Chikungunya virus and Sindbis virus are alphaviruses. 6. Crimean-Congo virus and Hantaan virus are bunyaviruses. 7. Therefore, the correct answer is C.

Correct Answer: B

Rationale: The correct answer is B: Personal eyewash. Personal eyewash is designed for immediate flushing until the victim reaches a more suitable safety unit. It provides a controlled flow of water to safely flush eyes while transporting the victim. The emergency shower (A) is meant for full-body coverage, not just for the eyes. Handheld drench hose (C) may not provide adequate flushing pressure. Combination unit (D) may not be easily portable for immediate use.

Correct Answer: B

Rationale: The correct answer is B: Treponema pallidum. 1. Treponema pallidum is a spirochete bacterium known to cause syphilis. 2. Borrelia burgdorferi causes Lyme disease, not syphilis. 3. Leptospira interrogans causes leptospirosis, not syphilis. 4. Rickettsia rickettsii causes Rocky Mountain spotted fever, not syphilis. Therefore, Treponema pallidum is the causative agent of syphilis, making it the correct answer.

Correct Answer: C

Rationale: The correct answer is C: Visceral leishmaniasis. This disease is caused by the protozoan parasite Leishmania, which is transmitted by sandfly bites. The symptoms described in the question, such as enlarged liver and spleen, peripheral gland enlargement, and eathy colored skin, are characteristic of visceral leishmaniasis. Amebiasis (choice A) typically presents with gastrointestinal symptoms, Balantidiasis (choice B) is caused by a different parasite and presents with dysentery, and Lambliasis (choice D) is caused by Giardia lamblia and presents with diarrhea.

Correct Answer: D

Rationale: The correct answer is D, Late congenital syphilis. This is because the patient presents with Hutchinson's teeth, which are a characteristic feature of late congenital syphilis. Hutchinson's teeth are small, barrel-shaped teeth with a wider cervix and notched incisors. The patient's history of visual impairment and hearing aid use also support the diagnosis of late congenital syphilis, as these are common manifestations of this stage of the disease. Choice A, Primary syphilis, is incorrect because it typically presents with a painless sore at the site of infection, not dental abnormalities. Choice B, Early congenital syphilis, is incorrect as dental abnormalities in this stage are usually more severe, such as mulberry molars. Choice C, Neurosyphilis, is incorrect as it primarily affects the central nervous system and does not typically present with dental abnormalities.

Correct Answer: C

Rationale: The correct answer is C: Obligate anaerobes. These bacteria cannot survive in the presence of oxygen as they lack the necessary enzymes to detoxify reactive oxygen species. Obligate aerobes (A) require oxygen, facultative anaerobes (B) can grow with or without oxygen, and aerotolerant anaerobes (D) can survive in the presence of oxygen but do not utilize it for growth.

Correct Answer: C

Rationale: The correct answer is C: Tularemia. Ticks can transmit tularemia, a bacterial infection caused by Francisella tularensis. Ticks pick up the bacteria when feeding on infected animals and can then transmit it to humans through their bites. Botulism (A) is caused by toxins produced by Clostridium botulinum bacteria, not transmitted by ticks. Anthrax (B) is a bacterial infection caused by Bacillus anthracis, typically transmitted through contact with contaminated animal products. MRSA (D) is a bacterial infection caused by Staphylococcus aureus, commonly transmitted through direct contact with infected individuals or contaminated surfaces, not by ticks.