Nokea
A patient consulted a dentist about itching and burning in the oral cavity; high temperature. The patient was diagnosed with trichomonal gingivostomatitis. What drug should be chosen for his treatment?
- A. Metronidazole
- B. Ampicillin
- C. Gentamicin sulfate
- D. Nystatin
Correct Answer: A
Rationale: Step 1: Trichomonal gingivostomatitis is caused by the parasite Trichomonas tenax.
Step 2: Metronidazole is the drug of choice for treating infections caused by anaerobic organisms like Trichomonas.
Step 3: Metronidazole effectively targets and eliminates Trichomonas parasites in the oral cavity.
Step 4: Therefore, the correct drug choice for treating trichomonal gingivostomatitis is Metronidazole.
Summary:
- Ampicillin (B) is an antibiotic effective against Gram-positive bacteria, not parasites.
- Gentamicin sulfate (C) is an antibiotic used for bacterial infections, not parasitic infections.
- Nystatin (D) is an antifungal medication used for treating fungal infections, not parasitic infections like trichomonal gingivostomatitis.
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Which of the following bacteria is known for producing a neurotoxin that causes paralysis?
- A. Clostridium botulinum
- B. Clostridium perfringens
- C. Escherichia coli
- D. Staphylococcus aureus
Correct Answer: A
Rationale: The correct answer is A: Clostridium botulinum. This bacterium produces the botulinum neurotoxin, which causes paralysis by blocking the release of acetylcholine at neuromuscular junctions. Clostridium perfringens causes gas gangrene, not paralysis. Escherichia coli is associated with gastrointestinal infections, not paralysis. Staphylococcus aureus produces enterotoxins causing food poisoning, not paralysis. Therefore, Clostridium botulinum is the correct choice based on its well-known association with paralysis due to botulinum neurotoxin production.
A patient with pneumonia had a sputum culture revealing Gram-positive diplococci. The bacteria were catalase-negative and alpha-hemolytic. What is the most likely causative agent?
- A. Streptococcus pneumoniae
- B. Staphylococcus aureus
- C. Neisseria meningitidis
- D. Klebsiella pneumoniae
Correct Answer: A
Rationale: Step 1: Gram-positive diplococci suggest a pneumococcal infection.
Step 2: Catalase-negative indicates Streptococcus.
Step 3: Alpha-hemolysis matches S. pneumoniae's characteristics.
Therefore, Streptococcus pneumoniae is the most likely causative agent. Staphylococcus aureus (B) is catalase-positive, Neisseria meningitidis (C) is Gram-negative, and Klebsiella pneumoniae (D) is not diplococci or alpha-hemolytic.
On the base of the clinical data a child was diagnosed with atypical pneumonia resistant to the effects of beta-lactam antibiotics. The patient's sputum was cultured and incubated in a special medium, which resulted in growth of microorganisms forming microscopic colonies with a dense center (looking like fried eggs). What microorganism caused the disease?
- A. Mycoplasma pneumoniae
- B. Klebsiella pneumoniae
- C. Str. pneumoniae
- D. L. pneumophila
Correct Answer: A
Rationale: The correct answer is A: Mycoplasma pneumoniae. Mycoplasma pneumoniae is a common cause of atypical pneumonia and is known to be resistant to beta-lactam antibiotics. The description of microorganisms forming microscopic colonies with a dense center resembling fried eggs is characteristic of Mycoplasma pneumoniae colonies seen on special media.
Summary of other choices:
B: Klebsiella pneumoniae is not typically associated with atypical pneumonia and does not exhibit the described colony morphology.
C: Streptococcus pneumoniae is not resistant to beta-lactam antibiotics and does not produce colonies with the described appearance.
D: Legionella pneumophila is associated with Legionnaires' disease, not atypical pneumonia, and does not form colonies resembling fried eggs.
Shigella sonnei can escape phagocytic clearance by which mechanism?
- A. Lysis of phagosome and replication in cytoplasm
- B. capsule-mediated inhibition of phagocytosis
- C. Inhibition of phagosome/lysosome fusion
- D. inhibition of opsonization mediated by protein A
Correct Answer: A
Rationale: The correct answer is A because Shigella sonnei escapes phagocytic clearance by lysing the phagosome and replicating in the cytoplasm. This allows the bacterium to avoid being destroyed by the acidic environment and enzymes in the phagolysosome. Choice B is incorrect as Shigella does not have a capsule. Choice C is incorrect because Shigella actually induces phagosome-lysosome fusion to facilitate its escape. Choice D is incorrect as protein A is a component of Staphylococcus aureus, not Shigella sonnei.
A relationship in which two organisms benefit is referred to as __________.
- A. commensalism
- B. mutualism
- C. parasitism
- D. competition
Correct Answer: B
Rationale: The correct answer is B: mutualism. In mutualism, both organisms benefit from the relationship. This is because they provide each other with resources or services that help both parties. In contrast, commensalism (A) is a relationship where one organism benefits while the other is neither helped nor harmed. Parasitism (C) is a relationship where one organism benefits at the expense of the other. Competition (D) is a relationship where both organisms are negatively affected as they compete for limited resources. Therefore, mutualism is the correct answer as it describes a mutually beneficial relationship between two organisms.