Studies document that postoperative antimicrobial administration is not necessary for many surgeries. Nasal flora include Staphylococcus , Streptococcus pyogenes , Strep pneumoniae, Moraxella and Haemophilus species Cefazolin 1-2 gm IV 30 min. 600 mg 30 min. If mouth or pharynx is entered a 2 gm dose of cefazolin is recommended for adequate coverage in serum and tissue. For penicillin allergic patients where the reaction is severe enough to warrant avoiding cephalosporins.
Risk is high for mixed infections of anaerobes, staphylococci and pseudomonas.
Also, patients with decreased renal function may need adjustment of gentamicin dose. Other gram negative bacilli, streptococci and staphylococci are occasionally isolated. Anaerobic bacteria are uncommon, but Clostridium is the most common when isolated. Cefazolin 1 gm IV 30 min. Bacteria isolated from bile during surgery are those most likely to be associated with wound infections.