ATI RN
microbiology chapter 10 test bank Questions
Question 1 of 5
A patient presented with fever, malaise, and an ulcerated lesion. A Gram stain of the lesion revealed large, Gram-positive rods. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Bacillus anthracis. Bacillus anthracis is the likely causative agent as it is a Gram-positive rod-shaped bacterium known to cause ulcerated lesions with associated fever and malaise. Anthrax typically presents with these symptoms and fits the description given in the question. Clostridium perfringens (Choice B) causes gas gangrene and typically presents with different symptoms. Clostridium tetani (Choice C) causes tetanus and is not associated with ulcerated lesions. Bacillus cereus (Choice D) is known for causing food poisoning and does not typically present with the symptoms described in the question.
Question 2 of 5
A patient with a wound infection had a Gram-positive cocci isolated from the sample. The bacteria were catalase-positive and coagulase-positive. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus aureus. This is because Staphylococcus aureus is Gram-positive, catalase-positive, and coagulase-positive, which matches the characteristics described in the question. Staphylococcus epidermidis is also Gram-positive but is coagulase-negative. Streptococcus pneumoniae is Gram-positive but is catalase-negative. Enterococcus faecalis is Gram-positive but is catalase-negative and coagulase-negative. Therefore, based on the given information, Staphylococcus aureus is the likely causative agent of the wound infection.
Question 3 of 5
Which bacteria are resistant to antibiotics and commonly found in hospitals?
Correct Answer: A
Rationale: The correct answer is A, Staphylococcus aureus (MRSA), because it is known to be resistant to many antibiotics commonly used in hospitals. MRSA poses a significant threat in healthcare settings due to its resistance, making it difficult to treat. Choice B, Escherichia coli, is not typically resistant to antibiotics. Choice C, Salmonella enterica, and Choice D, Vibrio cholerae, are not commonly associated with antibiotic resistance in hospitals. Therefore, A is the correct answer based on its well-documented antibiotic resistance in healthcare settings.
Question 4 of 5
A patient with a painful ulcer had a wound culture revealing Gram-negative rods with a characteristic 'safety pin' appearance. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis is a Gram-negative rod that exhibits a 'safety pin' appearance on staining due to bipolar staining. This bacterium is the causative agent of plague, which can present as painful ulcers known as buboes. Y. pestis is transmitted by fleas and can cause outbreaks in humans. Summary: - B: Francisella tularensis causes tularemia, not typically associated with painful ulcers. - C: Brucella abortus causes brucellosis, which does not typically present with painful ulcers. - D: Clostridium botulinum causes botulism, characterized by muscle weakness and paralysis, not painful ulcers.
Question 5 of 5
Which of the following bacteria can form spores that are resistant to extreme conditions?
Correct Answer: B
Rationale: The correct answer is B: Bacillus subtilis. Bacillus subtilis is a Gram-positive bacterium known for forming endospores, which are resistant structures that allow the bacteria to survive harsh conditions like heat, radiation, and desiccation. This ability to form spores helps Bacillus subtilis to endure unfavorable environments. Staphylococcus aureus (A), Pseudomonas aeruginosa (C), and Neisseria gonorrhoeae (D) do not form spores and lack the same level of resistance to extreme conditions as Bacillus subtilis.