ATI RN
microbiology chapter 1 test bank Questions
Question 1 of 5
A patient with pneumonia had a sputum smear stained by the Gram method revealing Gram-positive cocci in pairs. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Streptococcus pneumoniae. The presence of Gram-positive cocci in pairs indicates a bacterial morphology consistent with Streptococcus pneumoniae, a common cause of pneumonia. This bacterium is known to appear in pairs or short chains on Gram stain. Staphylococcus aureus (
B) typically presents as clusters of Gram-positive cocci, Neisseria meningitidis (
C) is a Gram-negative diplococcus, and Klebsiella pneumoniae (
D) is a Gram-negative rod, making them less likely causative agents in this scenario.
Question 2 of 5
H. Influenzae type b (Hib) causes:
Correct Answer: A
Rationale: The correct answer is A: Meningitides. H. Influenzae type b (Hib) is a bacterium known to cause meningitis, a serious infection of the protective membranes covering the brain and spinal cord. Hib does not typically cause tonsillitis, urinary tract infections, or gastroenteritis. Meningitis is a life-threatening condition that requires prompt treatment, making it crucial to identify Hib as the causative agent.
Question 3 of 5
Which bacteria is associated with the formation of dental caries (cavities)?
Correct Answer: B
Rationale: The correct answer is B: Streptococcus mutans. This bacterium is associated with the formation of dental caries due to its ability to metabolize sugars and produce acids that demineralize tooth enamel. Streptococcus pneumoniae (choice
A) is not typically associated with dental caries. Bacillus anthracis (choice
C) causes anthrax, not dental caries. Clostridium botulinum (choice
D) causes botulism, not dental caries. Streptococcus mutans' unique characteristics make it the correct choice for the bacteria associated with dental caries.
Question 4 of 5
In which of the following GIT infections, the pathogenesis consists mainly of invasion and intraepithelial multiplication without generalization of infectious process:
Correct Answer: C
Rationale:
Rationale:
1. Shigella invades and multiplies within the intestinal epithelial cells, causing inflammation and tissue damage locally.
2. It does not spread systemically, unlike Yersinia enterocolitica and Listeria monocytogenes.
3. Shigella's pathogenesis is focused on invasion and multiplication at the site of infection, leading to symptoms of dysentery.
4. Yersinia enterocolitica and Listeria monocytogenes can disseminate beyond the gastrointestinal tract, causing systemic infections.
Summary:
- A (Yersinia enterocolitica) and B (Listeria monocytogenes) are incorrect as they can generalize the infectious process.
- C (Shigella) is correct as it mainly involves invasion and intraepithelial multiplication without spreading systemically.
Question 5 of 5
Which bacteria are known for causing hospital-acquired infections?
Correct Answer: D
Rationale: The correct answer is D. Staphylococcus aureus, Escherichia coli, and Clostridium difficile are all known for causing hospital-acquired infections. Staphylococcus aureus can cause skin infections and pneumonia. Escherichia coli can lead to urinary tract infections. Clostridium difficile is associated with gastrointestinal infections. Each of these bacteria has been linked to healthcare-associated infections due to their ability to spread in healthcare settings.
Therefore, the correct answer is D.
Choices A, B, and C are incorrect because each of these bacteria individually is known to cause hospital-acquired infections.