Nokea
Microscopic examination of dental plaque revealed unicellular organisms with two layers in their cytoplasm and wide pseudopodia. What is the likely causative agent?
- A. Entamoeba gingivalis
- B. Entamoeba histolytica
- C. Trichomonas tenax
- D. Lamblia intestinalis
Correct Answer: A
Rationale: Rationale:
1. Unicellular organisms with two layers in cytoplasm = Entamoeba gingivalis.
2. Wide pseudopodia = characteristic of Entamoeba genus.
3. Entamoeba histolytica causes amoebic dysentery, not dental plaque.
4. Trichomonas tenax causes periodontal disease, not dental plaque.
5. Lamblia intestinalis causes giardiasis, not related to dental plaque.
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The so-called “red tide†is generally caused by which of the following organisms?
- A. Lichens
- B. Bacteria
- C. Pfiesteria
- D. Dinoflagellates
Correct Answer: D
Rationale: The correct answer is D: Dinoflagellates. Red tides are caused by the rapid growth of certain species of dinoflagellates, which are single-celled algae. These algae produce toxins that can harm marine life and humans. Lichens (A) are not associated with red tides. While some bacteria (B) can contribute to harmful algal blooms, they are not the primary cause of red tides. Pfiesteria (C) is a type of harmful algal species, but it is not the main organism responsible for red tides. Therefore, the correct answer is dinoflagellates (D) due to their ability to cause red tides through toxin production.
Which of the following bacteria is known for producing a biofilm on medical devices?
- A. Clostridium tetani
- B. Pseudomonas aeruginosa
- C. Salmonella enterica
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B: Pseudomonas aeruginosa. This bacterium is known for producing biofilms on medical devices due to its ability to adhere and form a slimy layer that protects it from antibiotics and the host immune system. Pseudomonas aeruginosa is commonly associated with healthcare-associated infections.
Clostridium tetani (A) causes tetanus, not known for biofilm production on medical devices. Salmonella enterica (C) causes foodborne illnesses, not typically associated with medical device biofilms. Staphylococcus aureus (D) is a common pathogen in healthcare settings but is not specifically known for biofilm production on medical devices.
Which bacterium is responsible for causing pneumonia?
- A. Streptococcus pneumoniae
- B. Mycobacterium tuberculosis
- C. Escherichia coli
- D. Clostridium botulinum
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is the most common cause of bacterial pneumonia in adults. It is a leading cause of community-acquired pneumonia. Streptococcus pneumoniae is known for its ability to infect the respiratory tract and cause inflammation in the lungs leading to pneumonia. Mycobacterium tuberculosis causes tuberculosis, not pneumonia. Escherichia coli is associated with urinary tract infections and gastrointestinal illnesses, not pneumonia. Clostridium botulinum causes botulism, a severe form of food poisoning, but not pneumonia. Therefore, the correct choice is Streptococcus pneumoniae as it is specifically known for causing pneumonia.
A 47-year-old patient came to see a doctor on the 7th day of disease. The disease developed very fast: after the chill body temperature rose to 40oC and lasted up to 7 hours, then dropped abruptly, which caused profuse sweat. There were three such attacks occur in once in two days. Two days ago the patient arrived from Africa. Objectively: pale skin, subicteric sclera, significantly enlarged liver and spleen. What is the cause of fever attacks in this disease?
- A. Erythrocytic schizogony
- B. Tissue schizogony
- C. Exotoxin of a causative agent
- D. Gametocytes
Correct Answer: A
Rationale: The correct answer is A: Erythrocytic schizogony. In this case, the patient most likely has malaria, specifically caused by Plasmodium falciparum. The fever attacks every 2 days (tertian fever) are characteristic of P. falciparum infection. The cycle of erythrocytic schizogony in P. falciparum is around 48 hours, leading to the recurring fever pattern. Choices B, C, and D are incorrect as tissue schizogony does not cause the characteristic fever pattern, exotoxins are not typically involved in malaria fever, and gametocytes do not directly cause fever attacks.
Which of the antibiotics listed below are not suitable for treatment of listeriosis?
- A. Penicillin and ampicillin
- B. Macrolids
- C. Cephalosporins
- D. None of them
Correct Answer: B
Rationale: The correct answer is B: Macrolides. Listeriosis is typically treated with antibiotics such as Penicillin and ampicillin due to their effectiveness against Listeria monocytogenes. Macrolides, on the other hand, are not first-line agents for listeriosis treatment. They are less effective in treating this bacterial infection compared to Penicillin and ampicillin. Cephalosporins may also be less effective against Listeria monocytogenes compared to Penicillin and ampicillin. Choice D is incorrect as Macrolides are not suitable for listeriosis treatment.