Which antibiotic is commonly used for surgical prophylaxis?

• A. Aztreonam
• B. Cefazolin
• C. Amoxicillin
• D. Doxycycline

Answer: (B)

Preventing surgical site infections relies on giving an antibiotic that targets the organisms most likely to contaminate the wound—skin flora like Staphylococcus species—and that reaches the tissues quickly at the start of surgery. Cefazolin fits well because it’s a first-generation cephalosporin with strong activity against Staphylococcus aureus and Staphylococcus epidermidis, plus some gram-negative coverage, and it penetrates tissues effectively. It has a favorable safety profile, is inexpensive, and its short half-life makes a single preoperative dose (timed just before incision) ideal for many procedures. Aztreonam mainly covers gram-negative bacteria and lacks coverage of the typical skin flora like Staph, so it isn’t used for standard prophylaxis against surgical-site infections. Amoxicillin is oral and doesn’t reliably cover Staphylococcus aureus in the perioperative setting, making it less suitable for surgery prophylaxis, and doxycycline isn’t the standard choice for routine prophylaxis due to its spectrum and pharmacokinetics. Overall, cefazolin is the best fit for routine surgical prophylaxis.