ATI RN
foundations in microbiology test bank Questions
Question 1 of 5
Which scientist performed the first successful vaccination against smallpox?
Correct Answer: B
Rationale: The correct answer is B: Jenner. Edward Jenner is credited with performing the first successful vaccination against smallpox in 1796. He used cowpox virus to inoculate individuals, leading to immunity against smallpox. Jenner's experiment laid the foundation for modern vaccination. Pasteur (A) is known for developing the germ theory of disease. Semmelweis (C) advocated for handwashing to prevent infections. Koch (D) identified the causative agents of several diseases but did not develop the smallpox vaccine.
Question 2 of 5
Which of the following is characteristic of Gram-negative bacteria?
Correct Answer: B
Rationale: The correct answer is B: Outer membrane containing lipopolysaccharides. Gram-negative bacteria have an outer membrane that contains lipopolysaccharides, which are important for protection and pathogenicity. This outer membrane is a unique feature of Gram-negative bacteria and is not present in Gram-positive bacteria, making it a key characteristic. A: Incorrect because Gram-negative bacteria have a thin peptidoglycan layer compared to Gram-positive bacteria. C: Incorrect because teichoic acids are a characteristic of Gram-positive bacteria, not Gram-negative bacteria. D: Incorrect because all bacteria, including Gram-negative bacteria, have a cell wall.
Question 3 of 5
A patient with severe pneumonia had a sputum culture revealing Gram-negative rods that are non-lactose fermenters. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Pseudomonas aeruginosa. This is because Pseudomonas aeruginosa is a common Gram-negative rod that is a non-lactose fermenter and a common cause of severe pneumonia, especially in immunocompromised individuals. It is also known for its resistance to many antibiotics, making it difficult to treat. Summary of other choices: B: Escherichia coli is a lactose fermenter and is not commonly associated with severe pneumonia. C: Klebsiella pneumoniae is a lactose fermenter and is more commonly associated with pneumonia in alcoholics or debilitated patients. D: Enterobacter cloacae is a lactose fermenter and is not a common cause of severe pneumonia.
Question 4 of 5
A patient with a productive cough and fever had a sputum smear revealing Gram-positive cocci in clusters. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. Staphylococcus aureus is a Gram-positive cocci bacterium that forms clusters and commonly causes pneumonia with a productive cough and fever. It is frequently found in sputum smears in such cases. Streptococcus pneumoniae (B) is another common cause of pneumonia but typically appears in pairs or chains, not clusters. Neisseria meningitidis (C) is a Gram-negative diplococcus that causes meningitis, not pneumonia. Klebsiella pneumoniae (D) is a Gram-negative bacterium that can cause pneumonia but appears as Gram-negative rods, not Gram-positive cocci in clusters.
Question 5 of 5
A blood culture from a patient with sepsis revealed Gram-positive cocci in pairs. The bacteria were catalase-negative and alpha-hemolytic. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. This is because the bacterium is Gram-positive cocci in pairs, catalase-negative, and alpha-hemolytic, which are characteristic features of S. pneumoniae. The other choices can be ruled out based on specific characteristics: B) Staphylococcus aureus is catalase-positive, C) Enterococcus faecalis is gamma-hemolytic, and D) Neisseria gonorrhoeae is a Gram-negative diplococcus. Therefore, based on the given information, S. pneumoniae is the most likely causative agent of the sepsis.