microbiology an introduction test bank

Correct Answer: C

Rationale: Rationale: 1. Pseudomonas aeruginosa is commonly found in hospital environments. 2. It is an opportunistic pathogen causing various nosocomial infections. 3. Its ability to develop resistance to antibiotics makes it a significant threat. 4. Corynebacterium diphtheriae causes diphtheria, not common nosocomial infections. 5. Shigella sonnei causes foodborne illness, not typically nosocomial infections. 6. "None of the above" is incorrect as Pseudomonas is indeed commonly associated with nosocomial infections.

Correct Answer: B

Rationale: The correct answer is B: Vibrio cholerae. Vibrio cholerae is a comma-shaped rod bacterium that causes high volume watery diarrhea by producing cholera toxin. This toxin leads to the secretion of large amounts of fluid into the intestines. Campylobacter jejuni (A) typically causes bloody diarrhea. Pseudomonas aeruginosa (C) and Proteus mirabilis (D) are not associated with high volume watery diarrhea.

Correct Answer: A

Rationale: Step 1: Gram-negative rod with safety pin appearance indicates bipolar staining. Step 2: Yersinia pestis is a Gram-negative rod causing bubonic plague. Step 3: Y. pestis has bipolar staining due to its unique F1 capsule. Step 4: The swollen lymph node and bacteremia are consistent with bubonic plague. Step 5: Therefore, the correct answer is A: Yersinia pestis. Summary: - B: Clostridium tetani causes tetanus, not characterized by a safety pin appearance. - C: Brucella melitensis causes brucellosis, not characterized by a safety pin appearance. - D: Pasteurella multocida causes animal bites infections, not characterized by a safety pin appearance.

Correct Answer: B

Rationale: The correct answer is B because live vaccines can potentially revert to a virulent form, although this is extremely rare. This is due to the live attenuated virus in the vaccine potentially mutating back to a more dangerous form. Live vaccines are designed to be weakened but there is a small risk of reversion. Therefore, statement B is not correct. A: This statement is correct as immunocompromised individuals may have adverse reactions to live vaccines due to their weakened immune system. C: This statement is correct as microbes with many serotypes can make it challenging to develop a vaccine that covers all variations. D: This statement is correct as side effects to vaccination, although usually mild and temporary, can occur in some individuals.

Correct Answer: B

Rationale: The correct answer is B: Actinomycosis. Actinomyces is a gram-positive bacterium that forms sulfur granules (druses) with gram-positive coloring in the center and filamentous structures resembling cones with gram-negative coloring. This morphology is characteristic of Actinomyces species. Fusobacteriosis (choice A) typically presents with gram-negative rods. Staphylococcal osteomyelitis (choice C) is caused by gram-positive staphylococci, not Actinomyces. Anaerobic infections (choice D) can be caused by various bacteria, but the specific morphology described in the question matches Actinomyces, making choice B the correct answer.