A gynaecologist was examining a patient and revealed symptoms of genital tract inflammation. A smear from vagina contains pyriform protozoa with a spine, flagella at their front; there is also an undulating membrane. What disease can be suspected?

Correct Answer: A

Rationale: The correct answer is A: Urogenital trichomoniasis. The presence of pyriform protozoa with a spine, flagella at their front, and an undulating membrane in a vaginal smear indicates Trichomonas vaginalis, the causative agent of urogenital trichomoniasis. Trichomonas vaginalis is sexually transmitted and causes vaginal discharge, itching, and inflammation. Lambliasis (choice B) is caused by Giardia lamblia, which is not characterized by the described features. Intestinal trichomoniasis (choice C) is caused by a different species, Tritrichomonas foetus, and presents with diarrhea in cattle. Toxoplasmosis (choice D) is caused by Toxoplasma gondii and typically affects the brain and other organs, not the genital tract.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Family Retroviridae is known for having a single-stranded RNA genome. 2. The (-) sign indicates that the RNA strand is negative-sense. 3. Therefore, the correct answer A, "Their capsid consists of two copies of ssRNA(-)," is accurate. Summary: - Choice B is incorrect because Retroviridae have simple type of symmetry. - Choice C is incorrect as Retroviridae are not enveloped viruses. - Choice D is incorrect because Retroviridae are enveloped viruses.

Correct Answer: A

Rationale: The correct answer is A: Neisser's staining. Neisser's staining is used to detect metachromatic granules in bacteria, which appear as dark blue-staining granules at the ends of rod-shaped bacteria in diphtheria. This technique specifically targets these granules, making it ideal for identifying Corynebacterium diphtheriae, the causative agent of diphtheria. Ziehl-Neelsen staining is used for acid-fast bacteria like Mycobacterium tuberculosis, Gram staining is for classifying bacteria based on cell wall composition, and Giemsa staining is used for detecting parasites and certain blood cells, making them incorrect for identifying granules in diphtheria.

Correct Answer: B

Rationale: The correct answer is B: to sequester iron from the environment. Siderophores are molecules produced by bacteria to chelate and acquire iron, an essential nutrient for their growth and survival. By sequestering iron, bacteria can compete with host cells and other microbes for this vital resource. This enhances their ability to thrive and establish infections. Choices A, C, and D are incorrect because siderophores do not directly enhance antibiotic resistance, form capsules, or perform oxidative phosphorylation. These functions are unrelated to the primary role of siderophores in iron acquisition.

Correct Answer: B

Rationale: The correct answer is B: Acute purulent lymphadenitis. The symptoms described indicate an acute bacterial infection of the lymph nodes. The presence of painful lymph nodes, erythema, and shiny appearance of the skin overlying the nodes suggest an inflammatory process. The rise in temperature and frequent pulse indicate an active infection. The white-coated tongue may be a sign of systemic involvement. The shaky gait may indicate systemic toxicity. Bubonic plague (A) presents with buboes, not just painful lymph nodes. Lymphogranulomatosis (C) is a type of lymphoma and would not present with these acute bacterial infection symptoms. Anthrax (D) typically presents with a black eschar and is less likely in this context.

Correct Answer: B

Rationale: The correct answer is B: Tuberculosis. The case describes a man with a perforation in the hard palate and features of caseous necrosis with granulation tissue, endovasculitis, and a cellular infiltration mainly of lymphocytes, epithelioid cells, and plasma cells. These findings are classic for tuberculosis infection, commonly seen in extrapulmonary sites like the oral cavity. Syphilis (choice A) typically presents with a painless ulcer and different histopathological features. Leprosy (choice C) presents with granulomas containing foamy macrophages. Scleroma (choice D) is caused by Klebsiella rhinoscleromatis and presents with chronic granulomatous inflammation.

Correct Answer: D

Rationale: The correct answer is D: interferes with protein synthesis. Cephalosporins are beta-lactam antibiotics that work by inhibiting bacterial cell wall synthesis, not protein synthesis. They are bactericidal and have a relatively broad spectrum of activity against various bacteria. Choice A, B, and C all describe characteristics of cephalosporins, making them incorrect options.

Correct Answer: C

Rationale: The correct staining technique for sputum smears obtained from a tuberculosis patient is Ziehl-Neelsen staining. This technique uses carbol fuchsin dye to stain the acid-fast bacteria, such as Mycobacterium tuberculosis, red. Here's a step-by-step rationale: 1. Ziehl-Neelsen staining is specifically designed to detect acid-fast bacteria like Mycobacterium tuberculosis. 2. Carbol fuchsin dye is used to penetrate the mycolic acid layer in the cell wall of the bacteria, making them resistant to decolorization. 3. Acid-alcohol is used as a decolorizer to remove the stain from non-acid-fast bacteria. 4. Methylene blue is used as a counterstain to visualize non-acid-fast bacteria in blue. Therefore, Ziehl-Neelsen staining is the most appropriate technique for identifying Mycobacterium tuberculosis in sputum smears. Other choices like Gram, Giemsa, and

Correct Answer: A

Rationale: The correct answer is A: Morphologic features. Bacterial families are classified based on their morphologic features such as shape, size, and arrangement. This classification helps in identifying and studying different bacterial species. Choice B, Geographic features, is incorrect as bacterial classification is not based on their geographic distribution. Choice C, Historical features, is incorrect as it does not play a role in the classification of bacterial families. Choice D, Physiologic features, is also incorrect as physiological characteristics are used for further classification within bacterial families, not as a general characteristic.