Correct Answer: A

Rationale: The correct answer is A: Bordetella pertussis. This bacterium causes whooping cough by attaching to the respiratory tract and releasing toxins that lead to severe coughing fits. Clostridium tetani causes tetanus, not whooping cough. Haemophilus influenzae can cause respiratory infections but not specifically whooping cough. Staphylococcus aureus is known for causing skin infections and not respiratory diseases like whooping cough. Therefore, the presence of Bordetella pertussis and its specific mechanism of causing whooping cough makes it the correct answer.

Correct Answer: A

Rationale: The correct answer is A: Clostridium tetani. This bacterium is responsible for causing tetanus due to its production of tetanus toxin. Clostridium perfringens (B) causes gas gangrene, Streptococcus pyogenes (C) causes strep throat and skin infections, and Escherichia coli (D) is a common gut bacteria that can cause food poisoning but not tetanus.

Correct Answer: A

Rationale: The correct answer is A: Burri-Gins. This staining method specifically targets the detection of capsules in bacteria. It involves staining the capsules with crystal violet and the background with safranin. This staining technique helps visualize the capsules as a distinct halo around the bacteria. Summary: - Choice B (Ziehl-Neelsen) is used for acid-fast staining to detect Mycobacterium species. - Choice C (Neisser) is used for staining Neisseria species. - Choice D (Gram) is a common staining method used to differentiate bacteria based on cell wall composition (Gram-positive and Gram-negative), but it does not specifically target capsules.

Correct Answer: A

Rationale: The correct answer is A: Clostridium perfringens. Gas gangrene is caused by Clostridium perfringens, a Gram-positive rod bacterium that produces spores. This bacterium is anaerobic and commonly found in soil, where it forms spores that can survive harsh conditions. Clostridium tetani causes tetanus, not gas gangrene. Bacillus anthracis causes anthrax, not gas gangrene. Clostridium botulinum causes botulism, not gas gangrene. Therefore, based on the characteristics of the microorganism described in the question, Clostridium perfringens is the correct identification.

Correct Answer: D

Rationale: The correct answer is D: Amebiasis. The patient's symptoms of gastrointestinal disturbance and liver abscess are indicative of an infection with Entamoeba histolytica, the protozoan parasite responsible for amebiasis. The patient's travel history to an African country also increases the likelihood of contracting this disease, as it is more prevalent in tropical regions. Toxoplasmosis (A) is primarily associated with exposure to cat feces, Leishmaniasis (B) is transmitted through sandfly bites, and Malaria (C) is caused by Plasmodium parasites transmitted through mosquito bites. Therefore, these options are incorrect given the patient's presentation and travel history.