Nokea
Which of the following is the causative agent of tetanus?
- A. Clostridium botulinum
- B. Clostridium tetani
- C. Bacillus anthracis
- D. Staphylococcus aureus
Correct Answer: B
Rationale: The correct answer is B: Clostridium tetani. This bacterium produces tetanospasmin toxin, causing tetanus. Clostridium botulinum (choice A) produces botulinum toxin, leading to botulism. Bacillus anthracis (choice C) causes anthrax, not tetanus. Staphylococcus aureus (choice D) can cause various infections, but not tetanus. Therefore, only Clostridium tetani is the causative agent of tetanus.
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During fibergastroscopy a patient with ulcer disease of the stomach, the mucosal biopsy is taken from the area of an ulcer. Impression smear is prepared from biopsy material and stained by Gram method; the rest of biopsy material is tested for urease activity. Microscopy of the impression smear revealed gram- negative spiral-shaped microorganisms, urease activity test is positive. What bacteria were detected?
- A. Helicobacter pylori
- B. Campilobacter jejuni
- C. Treponema pallidum
- D. Spirilla minor
Correct Answer: A
Rationale: The correct answer is A: Helicobacter pylori.
Rationale:
1. Gram-negative spiral-shaped microorganisms match the morphology of Helicobacter pylori.
2. Positive urease activity is a characteristic feature of Helicjsonacter pylori.
3. Helicobacter pylori is specifically associated with gastric ulcers and is a common pathogen in the gastrointestinal tract.
Summary:
Choice B, Campilobacter jejuni, is a gram-negative curved bacterium but is not typically associated with gastric ulcers or urease activity. Choice C, Treponema pallidum, is a spirochete bacterium causing syphilis, which is not related to gastric ulcers. Choice D, Spirilla minor, is a generic term for spiral-shaped bacteria and is not a specific pathogen associated with gastric ulcers or urease activity.
Sanitary bacteriological research on water by the membrane filter method revealed two red colonies on a membrane filter (Endo agar) through which 500 ml of analyzed water were passed. Calculate the coli index and coli titer of the analyzed water:
- A. 4 and 250
- B. 2 and 500
- C. 250 and 4
- D. 500 and 2
Correct Answer: A
Rationale: The correct answer is A: 4 and 250. Coli index is calculated by dividing the number of red colonies by the volume of water analyzed, which gives 2 red colonies / 500 ml = 4. Coli titer is the reciprocal of the coli index, so it is 1 / 4 = 250. This indicates the concentration of coliform bacteria in the water sample. Choices B, C, and D are incorrect as they do not follow the correct calculation steps for determining the coli index and coli titer. B has the correct coli index but incorrect coli titer. C and D have the values reversed, leading to incorrect results.
Non-gonococcal urethritis and cervicitis can be caused by
- A. Mycoplasma hominis
- B. Mycoplasma genitalium
- C. Ureaplasma urealyticum
- D. all of them
Correct Answer: D
Rationale: The correct answer is D because Mycoplasma hominis, Mycoplasma genitalium, and Ureaplasma urealyticum are all known to cause non-gonococcal urethritis and cervicitis. These organisms can infect the urogenital tract and lead to inflammation and symptoms in both males and females. Each of these bacteria has been identified as a common cause of these conditions through research and clinical studies. Therefore, since all three organisms are capable of causing non-gonococcal urethritis and cervicitis, the correct answer is D. The other choices (A, B, and C) are incorrect because each of them alone can cause these conditions, making option D the most comprehensive and accurate choice.
The main virulence factor of Neisseria meningitidis is?
- A. The polysaccharide capsule
- B. The beta lactamase
- C. The erythrogenic toxin
- D. None of the above
Correct Answer: A
Rationale: The correct answer is A: The polysaccharide capsule. The capsule of Neisseria meningitidis plays a crucial role in its virulence by preventing phagocytosis, allowing the bacteria to evade the host's immune system. This leads to increased survival and colonization in the host.
Choice B: The beta lactamase is incorrect because it is an enzyme that breaks down beta-lactam antibiotics and does not directly contribute to the virulence of Neisseria meningitidis.
Choice C: The erythrogenic toxin is incorrect as this toxin is produced by Streptococcus pyogenes, not Neisseria meningitidis.
Choice D: None of the above is incorrect as the polysaccharide capsule is indeed a key virulence factor of Neisseria meningitidis.
Which of the following bacteria is responsible for causing the disease known as syphilis?
- A. Treponema pallidum
- B. Neisseria gonorrhoeae
- C. Chlamydia trachomatis
- D. Escherichia coli
Correct Answer: A
Rationale: The correct answer is A: Treponema pallidum. This bacterium is responsible for causing syphilis due to its unique spiral shape and ability to penetrate mucous membranes. It is transmitted through sexual contact or from mother to child during childbirth. Neisseria gonorrhoeae causes gonorrhea, Chlamydia trachomatis causes chlamydia, and Escherichia coli is a common bacterium found in the gut. Therefore, they are not responsible for syphilis.