Page 928 - Basic _ Clinical Pharmacology ( PDFDrive )

914 SECTION VIII Chemotherapeutic Drugs

The proper selection and administration of antimicrobial
National Research Council (NRC) Wound prophylaxis are of utmost importance. Common indications for
Classification Criteria surgical prophylaxis are shown in Table 51–7. Cefazolin is the
prophylactic agent of choice for head and neck, gastroduodenal,
Clean: Elective, primarily closed procedure; respiratory, gas- biliary tract, gynecologic, and clean procedures. Local wound
trointestinal, biliary, genitourinary, or oropharyngeal tract infection patterns should be considered when selecting antimicro-
not entered; no acute inflammation and no break in tech- bial prophylaxis. The selection of vancomycin over cefazolin may
nique; expected infection rate ≤ 2%. be necessary in hospitals with high rates of methicillin-resistant
Clean contaminated: Urgent or emergency case that is S aureus or S epidermidis infections. The antibiotic should be pres-
otherwise clean; elective, controlled opening of respiratory, ent in adequate concentrations at the operative site before incision
gastrointestinal, biliary, or oropharyngeal tract; minimal and throughout the procedure; initial dosing is dependent on the
spillage or minor break in technique; expected infection volume of distribution, peak levels, clearance, protein binding,
rate ≤ 10%. and bioavailability. Parenteral agents should be administered dur-
Contaminated: Acute nonpurulent inflammation; major ing the interval beginning 60 minutes before incision. In cesarean
technique break or major spill from hollow organ; penetrat- section, the antibiotic is administered after umbilical cord clamp-
ing trauma less than 4 hours old; chronic open wounds to be ing. For many antimicrobial agents, doses should be repeated if
grafted or covered; expected infection rate about 20%. the procedure exceeds 2–6 hours in duration. Single-dose pro-
Dirty: Purulence or abscess; preoperative perforation of phylaxis is effective for most procedures and results in decreased
respiratory, gastrointestinal, biliary, or oropharyngeal tract; toxicity and antimicrobial resistance.
penetrating trauma more than 4 hours old; expected infec- Improper administration of antimicrobial prophylaxis leads
tion rate about 40%. 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 prophy-
4. The shortest possible course—ideally a single dose—of the laxis, and inappropriate use of broad-spectrum antibiotics.
most effective and least toxic antibiotic should be used.
5. The newer broad-spectrum antibiotics should be reserved for Nonsurgical Prophylaxis
therapy of resistant infections.
6. If all other factors are equal, the least expensive agent should Nonsurgical prophylaxis includes the administration of antimi-
be used. crobials to prevent colonization or asymptomatic infection as

TABLE 51–7 Recommendations for surgical antimicrobial prophylaxis.

Type of Operation Common Pathogens Drug of Choice
Cardiac (with median sternotomy) Staphylococci, enteric Gram-negative rods Cefazolin
Noncardiac, thoracic Staphylococci, streptococci, enteric Gram-negative rods Cefazolin
Vascular (abdominal and lower Staphylococci, enteric Gram-negative rods Cefazolin
extremity)
Neurosurgical (craniotomy) Staphylococci Cefazolin
Orthopedic (with hardware insertion) Staphylococci Cefazolin
Head and neck (with entry into the Staphylococcus aureus, oral flora Cefazolin + metronidazole
oropharynx)
Gastroduodenal S aureus, oral flora, enteric Gram-negative rods Cefazolin
Biliary tract S aureus, enterococci, enteric Gram-negative rods Cefazolin
Colorectal (elective surgery) Enteric Gram-negative rods, anaerobes Oral erythromycin + neomycin 1
Colorectal (emergency surgery or Enteric Gram-negative rods, anaerobes Cefoxitin, cefotetan, ertapenem, or
obstruction) cefazolin + metronidazole
Appendectomy, nonperforated Enteric Gram-negative rods, anaerobes Cefoxitin, cefotetan, or cefazolin +
metronidazole
Hysterectomy Enteric Gram-negative rods, anaerobes, enterococci, group B Cefazolin, cefotetan, or cefoxitin
streptococci
Cesarean section Enteric Gram-negative rods, anaerobes, enterococci, group B Cefazolin
streptococci
1
In conjunction with mechanical bowel preparation.