microbiology chapter 10 test bank

Correct Answer: A

Rationale: Rationale: Vibrio cholerae produces the exotoxin responsible for severe diarrhea. It causes cholera by disrupting the normal functioning of the intestines. Clostridium botulinum causes botulism, not diarrhea. Streptococcus pyogenes causes strep throat and skin infections. Salmonella enterica causes food poisoning, not severe diarrhea. Therefore, the correct answer is A.

Correct Answer: A

Rationale: The correct answer is A: Lowestein-Jensen. This is because Lowestein-Jensen medium is specifically designed to cultivate Mycobacterium tuberculosis, providing necessary nutrients and conditions for its growth. Loefller's medium is not optimal for cultivating M. tuberculosis. Choice C (All of the above) is incorrect as not all the options listed are suitable for cultivating M. tuberculosis. Choice D (None of the above) is also incorrect as Lowestein-Jensen is indeed the recommended growth medium for this bacterium.

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.

Correct Answer: A

Rationale: Step 1: Ziehl-Neelsen staining is a type of acid-fast staining used to detect acid-resistant bacteria like Mycobacterium species. Step 2: Acid-resistant bacteria have a high lipid content in their cell walls, making them resist decolorization with acid-alcohol. Step 3: Mycobacterium species, such as M. tuberculosis and M. leprae, are examples of acid-resistant bacteria. Step 4: Spores are not typically stained using Ziehl-Neelsen staining, making choice B incorrect. Step 5: Metachromatic bodies are stained using specific techniques like Albert's stain, not Ziehl-Neelsen staining, making choice C incorrect. Summary: Ziehl-Neelsen staining is specifically used for acid-resistant bacteria detection, making choice A the correct answer. Choices B and C are incorrect as they do not align with the purpose of Ziehl-Neelsen staining. Choice D is incorrect as Ziehl

Correct Answer: A

Rationale: Rationale: 1. Gram-positive cocci in clusters point to Staphylococcus or Micrococcus. 2. Catalase-positive eliminates Streptococcus. 3. Coagulase-positive distinguishes Staphylococcus aureus. 4. Thus, the causative agent is Staphylococcus aureus. Summary: - B: Streptococcus pyogenes is catalase-negative. - C: Enterococcus faecalis is catalase-negative. - D: Micrococcus luteus is catalase-positive but coagulase-negative.