ATI RN
microbiology basic and clinical principles test bank Questions
Question 1 of 5
Which of the following methods can be used for diagnosis of respiratory tract infections
Correct Answer: D
Rationale: The correct answer is D: All are correct. Culture of samples from the respiratory tract can identify specific pathogens, Immunofluorescence can detect viral antigens, and PCR can amplify and detect specific DNA/RNA sequences. Using all methods together provides a comprehensive approach for diagnosing respiratory tract infections. Culture alone may miss fastidious organisms, Immunofluorescence has limitations in sensitivity, and PCR requires specific primers.
Therefore, combining these methods increases the likelihood of accurate diagnosis by covering a range of pathogens and improving sensitivity and specificity.
Question 2 of 5
The cell envelope of Gram-negative bacteria is composed of:
Correct Answer: A
Rationale: The correct answer is A because Gram-negative bacteria have a unique cell envelope structure consisting of a cytoplasmic membrane, a peptidoglycan layer, and an outer membrane. The cytoplasmic membrane is the innermost layer that separates the cytoplasm from the external environment. The peptidoglycan layer provides structural support to the cell. The outer membrane acts as an additional protective barrier and contains lipopolysaccharides.
Choice B is incorrect because Gram-negative bacteria have an outer membrane in addition to the cytoplasmic membrane and peptidoglycan layer.
Choice C is incorrect because Gram-negative bacteria have more than just a peptidoglycan layer in their cell envelope.
Choice D is incorrect as the cell envelope of Gram-negative bacteria does have specific components.
Question 3 of 5
The time response measures all of the following except:
Correct Answer: A
Rationale: The correct answer is A: ED50. The time response does not measure the ED50 because ED50 refers to the effective dose needed to produce a response in 50% of the population, which is a dose-related concept, not a time-related one. Peak effect time, onset of response, and threshold level are all time-related measures in pharmacology. Peak effect time is the time taken to reach the maximum response, onset of response is the time taken for the response to start, and threshold level is the minimum dose or concentration required to produce a response.
Therefore, A is the correct answer as it is the only choice that is not a time-related measure in this context.
Question 4 of 5
Streptococcus pneumoniae are:
Correct Answer: B
Rationale: The correct answer is B: Alpha-hemolytic streptococci. Streptococcus pneumoniae are classified as alpha-hemolytic streptococci based on their ability to partially break down red blood cells, causing a greenish discoloration on blood agar plates. This distinguishes them from beta-hemolytic streptococci, which completely break down red blood cells. Streptococcus pneumoniae are not resistant to bile (choice
A), as they are bile soluble. They are not stained by the Ziehl-Neelsen staining method (choice
C), which is used for acid-fast bacteria such as Mycobacterium tuberculosis. They are sensitive to optochin (choice
D), which is a key differentiating factor in identifying them from other alpha-hemolytic streptococci.
Question 5 of 5
Microscopy of sputum from a tuberculosis patient revealed acid-fast rods stained red using the Ziehl-Neelsen method. What structural feature allows this staining?
Correct Answer: A
Rationale: The correct answer is A: Mycolic acid in the cell wall. Mycolic acid is a unique component of the cell wall of Mycobacterium species, including the causative agent of tuberculosis. The Ziehl-Neelsen method uses acid-fast staining, where mycolic acid confers resistance to decolorization by acid-alcohol, causing the bacteria to retain the red stain.
Choices B, C, and D are incorrect as capsules, flagella, and peptidoglycan layers do not directly contribute to acid-fast staining characteristic of Mycobacterium species.