The antibiotic should be active against common surgical wound pathogens; unnecessarily broad coverage should be avoided.
2.
The antibiotic should have proved efficacy in clinical trials.
3.
The antibiotic must achieve concentrations greater than the MIC of suspected pathogens, and these concentrations must be present at the time of incision.
TABLE 51–7 Recommendations for surgical antimicrobial prophylaxis.
Clean: Elective, primarily closed procedure; respiratory, gastrointestinal, biliary, genitourinary, or oropharyngeal tract not entered; no acute inflammation and no break in technique; expected infection rate ≤ 2%. Clean contaminated: Urgent or emergency case that is otherwise clean; elective, controlled opening of respiratory, gastrointestinal, biliary, or oropharyngeal tract; minimal spillage or minor break in technique; expected infection rate ≤ 10%. Contaminated: Acute nonpurulent inflammation; major technique break or major spill from hollow organ; penetrating trauma less than 4 hours old; chronic open wounds to be grafted or covered; expected infection rate about 20%. Dirty: Purulence or abscess; preoperative perforation of respiratory, gastrointestinal, biliary, or oropharyngeal tract; penetrating trauma more than 4 hours old; expected infection rate about 40%.
4.
The shortest possible course—ideally a single dose—of the most effective and least toxic antibiotic should be used.
5.
The newer broad-spectrum antibiotics should be reserved for therapy of resistant infections.
6.
If all other factors are equal, the least expensive agent should be used.
The proper selection and administration of antimicrobial prophylaxis are of utmost importance. Common indications for surgical prophylaxis are shown in Table 51–7. Cefazolin is the prophylactic agent of choice for head and neck, gastroduodenal, biliary tract, gynecologic, and clean procedures. Local wound infection patterns should be considered when selecting antimicrobial prophylaxis. The selection of vancomycin over cefazolin may be necessary in hospitals with high rates of methicillin-resistant S aureus or S epidermidis infections. The antibiotic should be present in adequate concentrations at the operative site before incision and throughout the procedure; initial dosing is dependent on the volume of distribution, peak levels, clearance, protein binding, and bioavailability. Parenteral agents should be administered during the interval beginning 60 minutes before incision. In cesarean section, the antibiotic is administered after umbilical cord clamping. For many antimicrobial agents, doses should be repeated if the procedure exceeds 2–6 hours in duration. Single-dose prophylaxis is effective for most procedures and results in decreased toxicity and antimicrobial resistance.
Improper administration of antimicrobial prophylaxis leads to excessive surgical wound infection rates. Common errors in antibiotic prophylaxis include selection of the wrong antibiotic, administering the first dose too early or too late, failure to repeat doses during prolonged procedures, excessive duration of prophylaxis, and inappropriate use of broad-spectrum antibiotics.
Nonsurgical prophylaxis includes the administration of antimicrobials to prevent colonization or asymptomatic infection as 1In conjunction with mechanical bowel preparation.
TABLE 51–8 Recommendations for nonsurgical antimicrobial prophylaxis.
1Prophylaxis is recommended for the following: dental procedures that involve manipulation of gingival tissue or the periapical region of teeth or perforation of the oral mucosa, and invasive procedure of the respiratory tract that involves incision or biopsy of the respiratory mucosa, such as tonsillectomy and adenoidectomy.