Which regimen provides coverage for penicillinase-resistant organisms, gram-negative aerobes, and anaerobes for surgical prophylaxis?

• A. Cefoxitin and gentamicin
• B. Vancomycin and penicillin G
• C. Nafcillin, gentamicin, and metronidazole
• D. Metronidazole, clindamycin, and cefoxitin

Answer: (C)

The key idea is providing broad surgical prophylaxis that protects against three major groups of bacteria: penicillinase-producing Staphylococcus (penicillinase-resistant organisms), gram-negative aerobes, and anaerobes. Nafcillin is a penicillinase-resistant penicillin, so it effectively covers penicillinase-producing Staphylococcus aureus (MSSA) that can cause wound infections. Gentamicin adds reliable activity against gram-negative aerobes such as E. coli and Klebsiella, which are common in postoperative infections. Metronidazole targets anaerobes, including Bacteroides species, which can complicate abdominal and pelvic surgeries. Put together, this combination covers the Staph we worry about in the surgical field, plus the gram-negatives and the anaerobes that can invade wounds, providing comprehensive prophylaxis. Other regimens may fail to provide one of these essential components, leaving a gap in protection.