medical microbiology test bank

Correct Answer: D

Rationale: The correct answer is D, "All of the above," because all three bacteria (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) can cause urinary tract infections. E. coli is the most common causative agent of UTIs, followed by Staphylococcus aureus and occasionally Pseudomonas aeruginosa. Each of these bacteria has different virulence factors that enable them to infect the urinary tract. Therefore, it is important to consider all three options when diagnosing and treating UTIs. Choices A, B, and C are incorrect because each of those bacteria can individually cause UTIs, so the correct answer is D, as it encompasses all the possible causative agents.

Correct Answer: C

Rationale: The correct answer is C: Bacillus subtilis. Bacillus subtilis is known for its spore-forming ability, which is a survival mechanism to withstand harsh conditions. Spore formation allows the bacteria to become dormant and resistant to heat, chemicals, and radiation. Escherichia coli (A) is not known for spore formation. Staphylococcus aureus (B) does not form spores either. Listeria monocytogenes (D) is a pathogenic bacterium but does not typically form spores.

Correct Answer: D

Rationale: The correct answer is D: decimal reduction time. This term represents the time required at a specific temperature to kill 90% of a bacterial population. It is a key parameter in microbiology to determine the effectiveness of a given heat treatment. Generation time (A) refers to the time it takes for a population to double in size. Thermal death time (B) is the shortest time needed to kill all organisms at a specific temperature. Sterilization time (C) is a general term and does not specifically refer to the time required to kill 90% of the population.

Correct Answer: A

Rationale: The correct answer is A: Streptococcus pneumoniae. This bacterium is a common cause of pneumonia and is known to appear as Gram-positive cocci in pairs with a capsule. The presence of a capsule is a key characteristic of S. pneumoniae. Staphylococcus aureus (B) is a Gram-positive cocci but typically does not have a capsule. Neisseria meningitidis (C) is a Gram-negative diplococcus, not a Gram-positive cocci. Klebsiella pneumoniae (D) is a Gram-negative rod, not a Gram-positive cocci. Therefore, based on the staining pattern and the presence of a capsule, Streptococcus pneumoniae is the most likely causative agent in this case.

Correct Answer: D

Rationale: The correct answer is D because fungi do not form flagella. Fungi reproduce sexually and asexually (A) through spores, have a cell wall (B) made of chitin, and are mostly aerobic or facultative anaerobes (C). Flagella are structures found in some protozoa and bacteria, not in fungi. Therefore, option D is the only statement that is not true about fungi.