A man with a history of multiple antibiotic resistance is given a prophylactic IV dose of antibiotic before surgery. As the antibiotic is being infused, the patient becomes flushed over most of his body. Which of the following antibiotics is most likely responsible?

Correct Answer: C

Rationale: Vancomycin causes ‘red man syndrome’ (flushing) due to histamine release if infused too rapidly.

Correct Answer: D

Rationale: Tetracycline (e.g., doxycycline) is effective against intracellular pathogens like Rickettsia, Mycoplasma, and Chlamydia.

Correct Answer: D

Rationale: Penicillins and sulfonamides frequently cause hypersensitivity reactions (e.g., rash, anaphylaxis), unlike erythromycin.

Correct Answer: B

Rationale: Cefoperazone inhibits vitamin K-dependent clotting factors, increasing bleeding risk with warfarin.

Correct Answer: B

Rationale: Metronidazole disrupts DNA in anaerobes, unlike ciprofloxacin (aerobic gram-negatives), rifampicin (RNA polymerase), or clinafloxacin (broad-spectrum).