Nokea
A defined microorganism can be isolated in pure culture:
- A. From liquid and solid media
- B. From liquid nutrient media
- C. Only from single colonies on solid media
- D. None of the above
Correct Answer: C
Rationale: The correct answer is C because isolating a defined microorganism in pure culture involves obtaining a single, distinct colony on solid media. This ensures that only one type of microorganism is present in the culture, preventing contamination. Liquid media can harbor multiple organisms, making it challenging to isolate a specific microorganism. Therefore, choice A is incorrect. Choice B is also incorrect as liquid nutrient media does not provide the necessary isolation required for pure culture. Choice D is incorrect because isolating from single colonies on solid media allows for the pure culture of the defined microorganism.
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Which of the following bacteria is associated with stomach ulcers?
- A. Escherichia coli
- B. Helicobacter pylori
- C. Bacillus cereus
- D. Clostridium difficile
Correct Answer: B
Rationale: The correct answer is B: Helicobacter pylori. This bacterium is associated with stomach ulcers as it can survive in the acidic environment of the stomach and produce substances that weaken the stomach lining. Escherichia coli (A) is associated with foodborne illnesses, not ulcers. Bacillus cereus (C) causes food poisoning. Clostridium difficile (D) is associated with antibiotic-associated colitis, not ulcers. Therefore, Helicobacter pylori is the correct answer based on its specific association with stomach ulcers.
A 32 year old patient complains about heartburn and dull pain in the epigastrium that appear 2-3 hours after meal. Exacerbations happen in spring and in autumn. The patient has food intolerance of eggs and fish. Objectively: stomach palpation reveals painfulness in the gastroduodenal area. Electrophasoduodenoscopy revealed a 5 mm ulcer on the anterior wall of duodenum. Urease test is positive. What is the most probable leading mechanism of disease development?
- A. Helicobacterial infection
- B. Dietary allergy
- C. Autoantibody production
- D. Reduced prostaglandin synthesis
Correct Answer: A
Rationale: The correct answer is A: Helicobacterial infection. This is the most probable leading mechanism of disease development in this case because the patient's symptoms, such as heartburn, epigastric pain, food intolerance, and presence of a duodenal ulcer with a positive urease test, are classic signs of Helicobacter pylori infection. This bacterium colonizes the stomach lining, leading to inflammation and ulcer formation. The exacerbations in spring and autumn could be due to seasonal variations in immune response.
Choice B: Dietary allergy is incorrect because the symptoms and findings in the patient are more indicative of an infectious etiology rather than an allergic reaction to specific foods.
Choice C: Autoantibody production is unlikely as there are no indications of an autoimmune process in this case.
Choice D: Reduced prostaglandin synthesis is not the leading mechanism as the symptoms and findings are more consistent with an infectious cause rather than a deficiency in prostaglandin synthesis.
A patient consulted a doctor about bowels disfunction. The doctor established symptoms of duodenitis and enteritis. Laboratory examination helped to make the following diagnosis: lambliosis. What medication should be administered?
- A. Metronidazole
- B. Erythromycin
- C. Monomycin
- D. Chingamin
Correct Answer: A
Rationale: Rationale: Metronidazole is the drug of choice for treating lambliosis due to its effectiveness against Giardia lamblia, the parasite causing the infection. Metronidazole works by disrupting the DNA structure of the parasite, leading to its death. Erythromycin (choice B) is not effective against Giardia lamblia. Monomycin (choice C) and Chingamin (choice D) are not commonly used for treating lambliosis. Therefore, choice A, Metronidazole, is the correct medication for this patient.
A patient with severe pneumonia had a sputum culture revealing Gram-negative rods that are non-lactose fermenters. What is the most likely causative agent?
- A. Pseudomonas aeruginosa
- B. Escherichia coli
- C. Klebsiella pneumoniae
- D. Enterobacter cloacae
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas aeruginosa is a common Gram-negative rod that is a non-lactose fermenter and a common cause of severe pneumonia, especially in immunocompromised individuals. It is also known for its resistance to many antibiotics, making it difficult to treat.
Summary of other choices:
B: Escherichia coli is a lactose fermenter and is not commonly associated with severe pneumonia.
C: Klebsiella pneumoniae is a lactose fermenter and is more commonly associated with pneumonia in alcoholics or debilitated patients.
D: Enterobacter cloacae is a lactose fermenter and is not a common cause of severe pneumonia.
Bacterial spores are used for:
- A. Protection against phagocytosis
- B. Reproduction
- C. Survival
- D. Nutrient storage
Correct Answer: C
Rationale: The correct answer is C: Survival. Bacterial spores are specialized structures that bacteria form to survive harsh conditions such as extreme temperatures or lack of nutrients. Spores are not used for protection against phagocytosis (A) as they are dormant structures and not actively involved in defense mechanisms. They are not for reproduction (B) as spores are a form of bacterial reproduction but not the primary purpose of spore formation. Spores do not serve as nutrient storage (D) as they are mainly used for survival during unfavorable conditions.