ATI RN
microbiology chapter 11 test bank Questions
Question 1 of 5
A patient with a sore throat and fever had a throat culture revealing Gram-positive cocci in chains. The bacteria were catalase-negative. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pyogenes. This bacterium fits the description of Gram-positive cocci in chains and is catalase-negative. S. pyogenes commonly causes sore throat (pharyngitis) and fever, making it the most likely causative agent in this scenario. Staphylococcus aureus (
B) is catalase-positive and is not typically associated with pharyngitis. Enterococcus faecalis (
C) is not typically found in chains and is rarely a cause of acute pharyngitis. Micrococcus luteus (
D) is not typically associated with pharyngitis and is catalase-positive.
Question 2 of 5
Enzymes used in ELISA are those except:
Correct Answer: A
Rationale: The correct answer is A: Β-lactamase. In ELISA, enzymes like alkaline phosphatase, horseradish peroxidase, and Β-galactosidase are commonly used as labels to detect the presence of specific molecules. Β-lactamase is not typically used in ELISA as it is an enzyme used to hydrolyze β-lactam antibiotics.
Therefore, it does not serve the purpose of detecting specific molecules in ELISA. Alkaline phosphatase, horseradish peroxidase, and Î’-galactosidase are preferred enzymes in ELISA due to their ability to produce a detectable signal when bound to specific molecules.
Question 3 of 5
A blood culture from a patient with sepsis revealed Gram-positive cocci in clusters. The bacteria were catalase-positive and coagulase-negative. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. This is supported by the characteristics of Gram-positive cocci in clusters, catalase-positive, and coagulase-negative. Staphylococcus epidermidis fits all these criteria, as it is a common skin commensal that can cause infections in immunocompromised individuals. Staphylococcus aureus (choice
B) is catalase-positive and coagulase-positive. Streptococcus pyogenes (choice
C) is catalase-negative. Enterococcus faecalis (choice
D) is catalase-negative and not typically seen in clusters.
Therefore, based on the given information, Staphylococcus epidermidis is the most likely causative agent.
Question 4 of 5
Cytoplasmic membrane of the prokaryotes consists of:
Correct Answer: D
Rationale: The correct answer is D: All of the above. The cytoplasmic membrane of prokaryotes consists of phospholipids which form a lipid bilayer, providing structure and selective permeability. Proteins are embedded in this membrane, serving various functions like transport and signaling. Carbohydrates may also be present on the surface for cell recognition.
Therefore, all three components (phospholipids, proteins, and carbohydrates) are essential parts of the prokaryotic cytoplasmic membrane. Option A, B, and C individually do not fully encapsulate the complexity and composition of the prokaryotic cytoplasmic membrane.
Question 5 of 5
Specify the microbiological characteristic of the air:
Correct Answer: A
Rationale: The correct answer is A: Contaminated. The air is never completely free of microorganisms, so it is considered contaminated. Microorganisms are ubiquitous in the environment. Permissible limits (
B) imply a specific standard, which is not relevant to the general microbiological characteristic of air. Almost pure (
C) and pure (
D) are not accurate as air always contains some level of microorganisms.