Nokea
A healthy man is in a region with high risk of catching malaria. What drug should be administered for individual chemoprophylaxis of malaria?
- A. Chingamin
- B. Sulfalen
- C. Tetracycline
- D. Metronidazole
Correct Answer: A
Rationale: The correct answer is A: Chingamin (also known as Chloroquine). Chingamin is the drug of choice for chemoprophylaxis of malaria in regions with high risk. It is effective against Plasmodium falciparum, the most common malaria parasite. Chingamin is well-tolerated, affordable, and has a long track record of use. Sulfalen (Choice B) is not commonly used for malaria prophylaxis. Tetracycline (Choice C) is not recommended for malaria prophylaxis due to poor efficacy and resistance development. Metronidazole (Choice D) is not effective against malaria parasites.
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Which of the following can be used for specific prophylaxis of pertussis?
- A. Pertussis toxoid
- B. Killed vaccine
- C. Wide-spectrum antibiotics
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: Pertussis toxoid. This is because pertussis toxoid is a component of the pertussis vaccine, which provides specific prophylaxis against pertussis by stimulating the immune system to produce antibodies against the bacteria causing the disease. Choice B, killed vaccine, is incorrect as it does not specify pertussis toxoid. Choice C, wide-spectrum antibiotics, is incorrect as antibiotics are used for treatment, not prophylaxis. Choice D, None of the above, is incorrect as pertussis toxoid is specifically used for prophylaxis of pertussis.
While examining a blood smear taken form a patient and stained by Romanovsky's method a doctor revealed some protozoa and diagnozed the patient with Chagas disease. What protozoan is the causative agent of this disease?
- A. Trypanosoma cruzi
- B. Toxoplasma gondii
- C. Leishmania donovani
- D. Leishmania tropica
Correct Answer: A
Rationale: Rationale:
1. Chagas disease is caused by Trypanosoma cruzi.
2. Trypanosoma cruzi is transmitted by triatomine bugs.
3. On a blood smear stained with Romanovsky's method, Trypanosoma cruzi appears as trypomastigotes.
4. Toxoplasma gondii causes toxoplasmosis, not Chagas disease.
5. Leishmania donovani and Leishmania tropica cause different forms of leishmaniasis, not Chagas disease.
A child with fever and a sore throat had a Gram-stained smear revealing Gram-positive cocci in chains. The bacteria were beta-hemolytic. What is the likely causative agent?
- A. Streptococcus pyogenes
- B. Streptococcus pneumoniae
- C. Staphylococcus aureus
- D. Enterococcus faecalis
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. The presence of Gram-positive cocci in chains suggests a streptococcal infection. Beta-hemolysis indicates the production of a hemolysin that lyses red blood cells, a characteristic of Streptococcus pyogenes. This bacterium is known to cause strep throat and can present with fever and sore throat.
Summary:
- B: Streptococcus pneumoniae is a common cause of pneumonia but typically appears as lancet-shaped cocci, not in chains.
- C: Staphylococcus aureus is a gram-positive cocci in clusters, not chains, and is not typically beta-hemolytic.
- D: Enterococcus faecalis is a gram-positive cocci that are part of the normal gut flora and are not typically beta-hemolytic or found in chains.
What microorganisms were accounted for in this case?
- A. All bacteria that have grown on a nutrient medium
- B. Opportunistic pathogenic bacteria
- C. Enteropathogenic bacteria and viruses
- D. Colibacilli
Correct Answer: C
Rationale: The correct answer is C because the case specifically mentions "enteropathogenic bacteria and viruses," indicating a focus on these specific microorganisms. Choice A is too broad and includes all bacteria, which is not specified in the case. Choice B mentions opportunistic pathogenic bacteria, which are not necessarily relevant to the case. Choice D specifies colibacilli, which may or may not be relevant to the case, but it is not as specific as choice C which clearly matches the information provided in the case.
Bacteria that use oxygen, but only at low concentration, are classified as:
- A. obligate aerobes
- B. microaerophiles
- C. obligate anaerobes
- D. aerotolerant anaerobes
Correct Answer: B
Rationale: The correct answer is B: microaerophiles. These bacteria require oxygen to grow, but only at low concentrations as higher levels can be toxic. They possess enzymes to deal with reactive oxygen species. Obligate aerobes (A) require oxygen for growth, obligate anaerobes (C) cannot survive in the presence of oxygen, and aerotolerant anaerobes (D) can tolerate oxygen but do not use it for growth.