microbiology basic and clinical principles test bank

microbiology basic and clinical principles test bank Related

Review microbiology basic and clinical principles test bank related questions and content

Microscopy of a smear taken from the film that appeared on the peptone water 6 hours after seeding and culturing of a fecal sample in a thermostat revealed mobile gram-negative bacteria curved in form of a comma that didn't make spores or capsules. What microorganisms were revealed?

  • A. Vibrios
  • B. Spirochetes
  • C. Clostridia
  • D. Corynebacteria
Correct Answer: A

Rationale: The correct answer is A: Vibrios. Vibrios are gram-negative curved bacteria that are motile and do not form spores or capsules. The description of the bacteria in the question fits the characteristics of Vibrios. Vibrios are commonly found in aquatic environments and some species can cause gastrointestinal infections in humans.

B: Spirochetes are also gram-negative curved bacteria, but they are spiral-shaped and have unique axial filaments for motility. The description in the question does not match the characteristics of spirochetes.

C: Clostridia are gram-positive, spore-forming bacteria. The question specifically states that the bacteria are gram-negative and do not form spores, ruling out Clostridia.

D: Corynebacteria are gram-positive, non-spore-forming bacteria. The description in the question does not match the characteristics of Corynebacteria.

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A sputum smear from a patient with pneumonia revealed Gram-positive cocci in pairs with pointed ends and capsules. What is the likely microorganism?

  • A. Streptococcus pneumoniae
  • B. Staphylococcus aureus
  • C. Klebsiella pneumoniae
  • D. Neisseria meningitidis
Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. The description of Gram-positive cocci in pairs with pointed ends and capsules matches the morphology of S. pneumoniae. This bacterium is known to cause pneumonia, especially in individuals with underlying conditions like COPD. Staphylococcus aureus (B) typically appears in clusters, not pairs. Klebsiella pneumoniae (C) is a Gram-negative rod, not a cocci. Neisseria meningitidis (D) is a Gram-negative diplococcus, not a cocci. Hence, based on the morphology and clinical context, Streptococcus pneumoniae is the likely microorganism causing pneumonia in this patient.

Name the halogen-containing antiseptic with fungicidal properties, which is used to treat dermatomycosis:

  • A. Iodine solution
  • B. Formalin solution
  • C. Methylene blue
  • D. Brilliant green
Correct Answer: A

Rationale: Rationale:
1. Iodine solution contains iodine, a halogen with antiseptic properties.
2. Iodine is effective against fungi, making it suitable for treating dermatomycosis.
3. Iodine solution is commonly used in dermatology for its fungicidal properties.
4. Formalin, methylene blue, and brilliant green do not contain halogens or have fungicidal properties.
Summary:
- Formalin is a disinfectant, not an antiseptic for dermatomycosis.
- Methylene blue is an antifungal dye, not used as an antiseptic.
- Brilliant green is an antiseptic, but does not contain halogens or have fungicidal properties.

A patient with a sore throat and fever had a throat culture revealing Gram-positive cocci in chains. The bacteria were beta-hemolytic. What is the most likely causative agent?

  • A. Streptococcus pyogenes
  • B. Streptococcus pneumoniae
  • C. Enterococcus faecalis
  • D. Staphylococcus aureus
Correct Answer: A

Rationale: The correct answer is A: Streptococcus pyogenes.
1. Gram-positive cocci in chains suggest streptococci.
2. Beta-hemolytic activity indicates Streptococcus pyogenes.
3. Streptococcus pyogenes is commonly associated with sore throat (pharyngitis) and fever.
4. Streptococcus pneumoniae (choice B) is alpha-hemolytic and mainly causes pneumonia.
5. Enterococcus faecalis (choice C) is not typically associated with sore throat.
6. Staphylococcus aureus (choice D) is not commonly beta-hemolytic and is not a typical cause of pharyngitis.

Treponema pallidum and Borrelia burgdorferi belong to the group of:

  • A. gram-negative aerobic rods and cocci
  • B. anaerobic gram-negative rods
  • C. anaerobic gram-negative cocci
  • D. spirochetes
Correct Answer: D

Rationale: Step-by-step rationale:
1. Treponema pallidum and Borrelia burgdorferi are both spirochetes.
2. Spirochetes are characterized by their spiral shape and unique motility.
3. Both organisms exhibit corkscrew-like movement due to axial filaments.
4. Other choices are incorrect as Treponema and Borrelia are not gram-negative rods, cocci, or anaerobic cocci.
Summary:
The correct answer is D because Treponema pallidum and Borrelia burgdorferi are spirochetes, characterized by their spiral shape and motility. Other choices are incorrect as they do not accurately describe the characteristics of these organisms.

A patient suffers from severe postoperative pseudomonadous infection. What of the following antibiotics should be administered in this case?

  • A. Amicacin sulfate
  • B. Benzylpenicillin
  • C. Cephazolin
  • D. Erythromycin
Correct Answer: A

Rationale: The correct answer is A: Amikacin sulfate. Pseudomonas aeruginosa is commonly resistant to many antibiotics, but aminoglycosides like Amikacin have good activity against it. Step 1: Identify the pathogen causing the infection. Step 2: Consider the antibiotic's spectrum of activity against the pathogen. Step 3: Choose an antibiotic with proven efficacy. Amikacin is a good choice due to its effectiveness against Pseudomonas. Choice B, Benzylpenicillin, is a penicillin which is not effective against Pseudomonas. Choice C, Cephazolin, is a cephalosporin with limited activity against Pseudomonas. Choice D, Erythromycin, is a macrolide which is not effective against Pseudomonas.

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