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A patient has food poisoning. Laboratory analysis revealed a culture of anaerobic gram-positive spore-forming bacteria. What is the most likely kind of the isolated causative agent?
- A. C. perfringens
- B. Proteus vulgaris
- C. P. mirabilis
- D. Vibrio parahemolyticus
Correct Answer: A
Rationale: The correct answer is A: C. perfringens. This is because Clostridium perfringens is a gram-positive, anaerobic, spore-forming bacterium commonly associated with food poisoning. It produces toxins that cause gastrointestinal symptoms. Proteus vulgaris (B) and P. mirabilis (C) are gram-negative bacteria not typically associated with food poisoning. Vibrio parahemolyticus (D) is a gram-negative bacterium causing seafood-related gastroenteritis, not spore-forming or anaerobic.
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Ionizing radiation involves all of the following except
- A. UV light
- B. Gamma rays
- C. Electron beams
- D. X-rays
Correct Answer: A
Rationale: Ionizing radiation has enough energy to remove tightly bound electrons from atoms, creating charged particles (ions). UV light does not have enough energy to ionize atoms, making choice A the correct answer. Gamma rays, electron beams, and X-rays all have sufficient energy to cause ionization. Gamma rays are very high-energy electromagnetic radiation, electron beams are streams of high-energy electrons, and X-rays are high-energy electromagnetic radiation as well.
A patient was taken to a hospital with acute food poisoning caused by homemade canned mushrooms. The product analysis revealed some microorganisms that develop only in the absence of oxygen. What microorganisms caused the poisoning?
- A. Obligate anaerobes
- B. Facultative anaerobes
- C. Microaerophiles
- D. Obligate aerobes
Correct Answer: A
Rationale: The correct answer is A: Obligate anaerobes. These microorganisms thrive in the absence of oxygen, as seen in the canned mushrooms where oxygen is limited. They produce toxins causing food poisoning. Facultative anaerobes (B) can survive with or without oxygen. Microaerophiles (C) require low levels of oxygen. Obligate aerobes (D) need oxygen to survive and would not be responsible for the poisoning in this case.
For family Rhabdoviridae is true that:
- A. They are enveloped viruses
- B. They cause plague
- C. They have spherical shape
- D. They infect only humans
Correct Answer: A
Rationale: The correct answer is A: They are enveloped viruses. Rhabdoviridae family consists of enveloped viruses, which means they have a lipid envelope surrounding their protein coat. This envelope helps the virus in infecting host cells and evading the immune system. The other choices are incorrect because B: They cause plague is not true as Rhabdoviridae family typically causes diseases like rabies in mammals. C: They have spherical shape is incorrect as rhabdoviruses have a bullet-shaped structure. D: They infect only humans is also incorrect as Rhabdoviridae viruses can infect a wide range of hosts beyond just humans.
Which of the following stains is the most widely used differential stain in hematology laboratories?
- A. Carbolfuchsin stain
- B. Wright’s stain
- C. Ziehl-Neelson stain
- D. Kinyoun stain
Correct Answer: D
Rationale: The correct answer is D: Kinyoun stain. This stain is the most widely used differential stain in hematology labs because it is specifically designed for acid-fast bacteria like Mycobacterium tuberculosis. It differentiates these bacteria from others based on their cell wall composition. Carbolfuchsin stain (A) is used for acid-fast bacteria in microbiology. Wright's stain (B) is used for blood cell morphology. Ziehl-Neelsen stain (C) is also used for acid-fast bacteria but is less commonly used compared to Kinyoun stain in hematology labs.
A 60-year-old patient was hospitalized to the surgical department because of infection caused by blue pus bacillus (Pseudomonas aeruginosa) which is sensative to penicillin antibiotics. Indicate which of the given penicillins has marked activity to the Pseudomonas aeruginosa?
- A. Carbenicillin disodium
- B. Benzylpenicillin
- C. Methicillin
- D. Oxacillin
Correct Answer: A
Rationale: The correct answer is A: Carbenicillin disodium. Carbenicillin is a semisynthetic penicillin that has marked activity against Pseudomonas aeruginosa. This is due to its extended spectrum of activity and increased stability against beta-lactamases produced by Pseudomonas aeruginosa. Carbenicillin is commonly used to treat infections caused by this bacterium.
Choice B: Benzylpenicillin (Penicillin G) has limited activity against Pseudomonas aeruginosa.
Choice C: Methicillin is not effective against Pseudomonas aeruginosa.
Choice D: Oxacillin also has limited activity against Pseudomonas aeruginosa.
In summary, Carbenicillin is the correct choice due to its marked activity against Pseudomonas aeruginosa compared to the other penicillins listed.