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A patient with pneumonia had sputum cultured on Endo agar, revealing red colonies. The bacteria were Gram-negative rods. What is the most likely causative agent?
- A. Escherichia coli
- B. Klebsiella pneumoniae
- C. Pseudomonas aeruginosa
- D. Proteus mirabilis
Correct Answer: A
Rationale: Rationale for correct answer (A: Escherichia coli):
1. Endo agar selects for Gram-negative bacteria.
2. Red colonies on Endo agar indicate lactose fermentation, characteristic of E. coli.
3. E. coli is a common cause of pneumonia, especially in immunocompromised patients.
Summary of why other choices are incorrect:
- B: Klebsiella pneumoniae: Typically forms mucoid colonies on agar.
- C: Pseudomonas aeruginosa: Produces characteristic greenish-blue colonies on agar.
- D: Proteus mirabilis: Does not typically ferment lactose, so would not produce red colonies on Endo agar.
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Systemic amebiasis with involvment of intestines, liver, lungs was diagnosed in a 52-year-old patient. What drug should be prescribed?
- A. Quiniofone
- B. Enteroseptol
- C. Metronidazole
- D. Tetracycline
Correct Answer: C
Rationale: Rationale: Metronidazole is the drug of choice for systemic amebiasis due to its high efficacy against Entamoeba histolytica. It has good tissue penetration and can treat intestinal, liver, and lung involvement. Quiniofone (A) has limited use and is not recommended for amebiasis. Enteroseptol (B) is not effective against systemic amebiasis. Tetracycline (D) is not the first-line treatment for amebiasis and has limited efficacy against Entamoeba histolytica.
A patient presented with a painful, swollen lymph node, and bacteremia. A Gram-negative rod with a characteristic safety pin appearance was observed. What is the causative agent?
- A. Yersinia pestis
- B. Clostridium tetani
- C. Brucella melitensis
- D. Pasteurella multocida
Correct Answer: A
Rationale: Step 1: Gram-negative rod with safety pin appearance indicates bipolar staining.
Step 2: Yersinia pestis is a Gram-negative rod causing bubonic plague.
Step 3: Y. pestis has bipolar staining due to its unique F1 capsule.
Step 4: The swollen lymph node and bacteremia are consistent with bubonic plague.
Step 5: Therefore, the correct answer is A: Yersinia pestis.
Summary:
- B: Clostridium tetani causes tetanus, not characterized by a safety pin appearance.
- C: Brucella melitensis causes brucellosis, not characterized by a safety pin appearance.
- D: Pasteurella multocida causes animal bites infections, not characterized by a safety pin appearance.
Medical examination of the first-year pupils included Mantoux test. 15 pupils out of 35 had negative reaction. What actions should be taken against children with negative reaction?
- A. BCG vaccination
- B. Antitoxin vaccination
- C. Rabies vaccination
- D. Repeat Mantoux test
Correct Answer: A
Rationale: The correct answer is A: BCG vaccination. The Mantoux test is used to detect tuberculosis infection. A negative reaction means the child is not infected. BCG vaccination is recommended for individuals without prior TB infection to prevent severe forms of the disease. Antitoxin and rabies vaccinations are not related to TB and are not indicated in this scenario. Repeating the Mantoux test is unnecessary since a negative result indicates absence of TB infection.
UN volunteers have arrived in Nigeria to assist the locals in aftermath of earthquakes. What drug should they prescribe for individual chemoprophylaxis of malaria?
- A. Chingamin
- B. Pyrantel
- C. Pyrimethamine (Chloridinum)
- D. Primaquine
Correct Answer: D
Rationale: The correct answer is D: Primaquine. Primaquine is used for individual chemoprophylaxis of malaria caused by Plasmodium vivax and Plasmodium ovale. It is effective in preventing the relapse of these malaria species by eliminating the liver forms of the parasites. Chingamin (A) is not a commonly used drug for malaria prophylaxis. Pyrantel (B) is an anthelmintic drug used for treating parasitic worm infections, not malaria. Pyrimethamine (Chloridinum) (C) is primarily used in combination with sulfadoxine for treating uncomplicated malaria, not for chemoprophylaxis.
Which bacteria produce endotoxins that can cause septic shock?
- A. Escherichia coli
- B. Salmonella enterica
- C. Pseudomonas aeruginosa
- D. All of the above
Correct Answer: D
Rationale: The correct answer is D. Escherichia coli, Salmonella enterica, and Pseudomonas aeruginosa all produce endotoxins that can lead to septic shock. Endotoxins are part of the outer membrane of Gram-negative bacteria and can trigger a systemic inflammatory response if released into the bloodstream. E. coli and Salmonella are common causes of bacterial infections that can lead to septic shock, while P. aeruginosa is a known opportunistic pathogen that can produce endotoxins. Therefore, all three bacteria can cause septic shock by releasing endotoxins. Choices A, B, and C are incorrect because each of these bacteria individually can produce endotoxins that contribute to the development of septic shock.