ATI RN
microbiology chapter 1 test bank Questions
Question 1 of 5
The bacteria responsible for tuberculosis is:
Correct Answer: A
Rationale: Step-by-step rationale: 1. Mycobacterium tuberculosis is the causative agent of tuberculosis. 2. Mycobacterium tuberculosis is a slow-growing, acid-fast bacterium. 3. It primarily infects the lungs and can spread to other parts of the body. 4. Bacillus anthracis causes anthrax, Clostridium tetani causes tetanus, and Treponema pallidum causes syphilis. 5. Therefore, choice A, Mycobacterium tuberculosis, is the correct answer for the bacteria responsible for tuberculosis.
Question 2 of 5
A patient with foul-smelling diarrhea had a stool sample showing large ciliated protozoa with a kidney-shaped macronucleus. What is the diagnosis?
Correct Answer: A
Rationale: The correct answer is A: Balantidiasis. The large ciliated protozoa with a kidney-shaped macronucleus described in the stool sample is consistent with Balantidium coli, the causative agent of balantidiasis. Balantidium coli is the only ciliated protozoan parasite that infects humans and presents with these specific characteristics. Giardiasis (B) is caused by Giardia intestinalis, which is flagellated, not ciliated. Amoebiasis (C) is caused by Entamoeba histolytica, which has an amoeboid shape, not ciliated. Trichomoniasis (D) is caused by Trichomonas vaginalis, which is a flagellated protozoan and does not have a kidney-shaped macronucleus. Hence, the correct diagnosis in this case is Balantidiasis.
Question 3 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 4 of 5
A child with an enlarged, painful lymph node had Gram-negative rods with a safety pin appearance. What is the causative agent?
Correct Answer: A
Rationale: The correct answer is A: Yersinia pestis. Y. pestis causes bubonic plague, characterized by enlarged, painful lymph nodes called buboes. The Gram-negative rods with a safety pin appearance are seen on Gram stain of Y. pestis. The other choices are incorrect because Francisella tularensis causes tularemia, not lymphadenitis with safety pin appearance. Brucella abortus causes brucellosis, which typically does not present with lymphadenitis. Clostridium botulinum causes botulism, which is not associated with lymphadenitis or safety pin appearance.
Question 5 of 5
A stool sample from a patient with severe diarrhea revealed non-lactose-fermenting, Gram-negative rods on Endo agar. What is the likely causative agent?
Correct Answer: A
Rationale: The correct answer is A: Shigella dysenteriae. It is the likely causative agent because it is a non-lactose-fermenting, Gram-negative rod commonly associated with severe diarrhea. Shigella dysenteriae specifically causes bacillary dysentery. Other choices are incorrect because: B: Escherichia coli is a lactose-fermenting bacterium commonly found in the gut and not typically associated with severe diarrhea. C: Salmonella typhi causes typhoid fever, not severe diarrhea. D: Proteus mirabilis is a urease-positive bacterium associated with urinary tract infections, not severe diarrhea.