ATI RN
microbiology an introduction 12th edition test bank Questions
Question 1 of 5
The process in which bacteria take up foreign DNA from the environment is called:
Correct Answer: A
Rationale: The correct answer is A: Transformation. During transformation, bacteria take up foreign DNA from the environment and incorporate it into their own genetic material. This process allows for genetic diversity and adaptation. Transduction (B) involves transfer of DNA via a virus, conjugation (C) involves direct transfer of DNA between bacterial cells, and binary fission (D) is a form of asexual reproduction in bacteria. Transformation is the only process specifically related to bacteria taking up foreign DNA.
Question 2 of 5
A patient with a productive cough and fever had a Gram-positive cocci isolated from a sputum sample. The bacteria were catalase-positive and coagulase-negative. What is the likely microorganism?
Correct Answer: A
Rationale: The correct answer is A: Staphylococcus epidermidis. 1. Gram-positive cocci suggest a staphylococcal species. 2. Catalase-positive indicates it belongs to the Staphylococcus genus. 3. Coagulase-negative rules out Staphylococcus aureus. 4. Staphylococcus epidermidis is a common cause of infections in immunocompromised patients. Summary: - B: Staphylococcus aureus is coagulase-positive. - C: Streptococcus pneumoniae is a Gram-positive diplococci. - D: Neisseria meningitidis is a Gram-negative diplococci.
Question 3 of 5
Which bacteria produce a toxin that inhibits protein synthesis?
Correct Answer: A
Rationale: The correct answer is A: Shigella dysenteriae. This bacteria produces the Shiga toxin, which inhibits protein synthesis by interfering with the ribosomes. Shigella dysenteriae causes severe gastrointestinal illness. The other choices, B: Clostridium botulinum, produces a neurotoxin that blocks neurotransmitter release. C: Streptococcus pneumoniae causes pneumonia and other respiratory infections. D: Mycobacterium tuberculosis causes tuberculosis by infecting the lungs. Thus, based on the toxin production and mode of action, Shigella dysenteriae is the correct answer.
Question 4 of 5
A child with fever and swollen lymph nodes had a Gram-stained smear revealing Gram-negative rods with a safety pin appearance. What is the causative agent?
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. This bacterium causes the plague, which presents with fever and swollen lymph nodes. The safety pin appearance on Gram stain is characteristic of Yersinia pestis. B: Francisella tularensis causes tularemia, which presents differently and does not show safety pin appearance on Gram stain. C: Brucella abortus causes brucellosis, which does not typically present with the same symptoms as described in the question. D: Clostridium botulinum causes botulism, which does not show safety pin appearance on Gram stain and does not typically present with fever and swollen lymph nodes.
Question 5 of 5
A stool sample from a patient with chronic diarrhea revealed cysts with four nuclei. What is the most likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Entamoeba histolytica. This is because it is a protozoan parasite known to cause amoebic dysentery, presenting with chronic diarrhea and cysts with four nuclei in the stool sample. Giardia lamblia (B) causes giardiasis with trophozoites and cysts with two nuclei. Balantidium coli (C) is a ciliated parasite causing dysentery with large trophozoites. Trichomonas hominis (D) is a non-pathogenic flagellate often found in the human intestine. Thus, based on the specific characteristics of the cysts and clinical presentation, Entamoeba histolytica is the most likely causative agent.