This document discusses surgical infections and the use of antibiotics. It defines surgical infections and describes various pathogens that commonly cause infections, including Streptococcus, Staphylococcus, gram-negative organisms, and Clostridia. It also discusses specific infections such as surgical site infections, necrotizing fasciitis, tetanus, and pseudomembranous colitis. The document concludes by outlining guidelines for antibiotic prophylaxis and treatment based on the classification of surgical wounds.