A puncture sample has been taken from the inguinal lymph nodes of a patient provisionally diagnosed with plague. The sample was inoculated into a hard nutrient medium. What shape will the colonies have, if the diagnosis is confirmed?

Correct Answer: B

Rationale: The correct answer is B: Shagreen leather. Yersinia pestis, the bacterium causing plague, forms colonies resembling shagreen leather on a hard nutrient medium due to its distinctive morphology. This morphology includes a rough, irregular, and raised appearance, similar to the texture of shagreen leather. A: Dewdrops - Incorrect. Dewdrops do not accurately describe the colony morphology of Yersinia pestis. C: Lace handkerchief - Incorrect. Lace handkerchief does not accurately describe the colony morphology of Yersinia pestis. D: Mercury drops - Incorrect. Mercury drops do not accurately describe the colony morphology of Yersinia pestis.

Correct Answer: C

Rationale: Step 1: Antitetanus serum is crucial for patients with open maxillofacial trauma to prevent tetanus infection from contaminated wounds. Step 2: Antibiotics are needed to prevent infection in the wound. Step 3: Antitetanus serum provides immediate passive immunity while antibiotics help combat potential infections. Step 4: Antitetanus immunoglobulin is not mentioned in the question and is not typically used for prophylaxis. Step 5: Anticonvulsive drugs are not preventive medications for maxillofacial trauma. Step 6: Diphtheria, tetanus, and pertussis vaccines are not specifically indicated for immediate prevention in this scenario.

Correct Answer: A

Rationale: The correct answer is A: Neutralization reaction. This is the most appropriate serological test to reveal botulinum toxin because it involves mixing the patient's serum with known botulinum antitoxin. If the patient's serum contains botulinum toxin, it will neutralize the antitoxin, leading to a lack of toxin-neutralizing ability. The other choices are incorrect because agglutination reaction involves clumping of cells, not suitable for detecting botulinum toxin; Bordet-Gengou test is used to detect antibodies in pertussis infection, not botulinum toxin; and precipitation reaction involves the formation of a solid when two solutions are mixed, not ideal for detecting botulinum toxin.

Correct Answer: A

Rationale: The correct answer is A: Bordetella. The presence of mercury-drop like colonies on Bordet-Gengou agar indicates Bordetella pertussis. The small ovoid gram-negative bacilli sized 1-3 microns are characteristic of Bordetella species. Catarrhal symptoms are typical of pertussis caused by Bordetella pertussis. Summary of other choices: B: Corynebacteria do not typically exhibit mercury-drop like colonies or small ovoid shapes. C: Mycobacteria are acid-fast bacilli and do not grow on Bordet-Gengou agar. D: Meningococcus is a gram-negative diplococcus and does not match the description provided.

Correct Answer: A

Rationale: The correct answer is A: Leptospira interrogans. Darkfield microscopy is used to visualize spirochetes, which are spiral-shaped bacteria. Leptospira is a spirochete bacterium that causes leptospirosis, which presents with jaundice, muscle aching, chill, and nosebleeds. Leptospira is commonly transmitted through contact with contaminated water or soil. B: Borrelia dutlonii causes Lyme disease, which is transmitted by ticks and does not typically present with jaundice or nosebleeds. C: Calymmatobacterium granulomatis causes granuloma inguinale, a sexually transmitted infection that does not present with the symptoms described. D: Bartonella bacilloformis causes Carrion's disease, which presents with fever, anemia, and skin lesions but not jaundice or nosebleeds.