Antimicrobial prophylaxis in surgery

Antimicrobial prophylaxis refers to the prevention of infection complications following surgical procedures. Such infections are observed with relative frequency, even after "sterile" operations. An estimated 5 to 10 percent of hospitalized patients undergoing otolaryngology ("head and neck") surgery acquire a nosocomial ("hospital") infection, which adds a substantial cost and an average of 4 extra days to the hospital stay. Urinary tract infections are the most common nosocomial infections (accounting for more than 7 million physician visits every year in the United States), and are second in seriousness to respiratory infections.

Antibiotics are effective in reducing the occurrence of such infections, even in "sterile" operative cases, as long as the drugs are properly selected and administered. Patients should be selected for prophylaxis if the medical condition or the surgical procedure is associated with a considerable risk of infection or if a postoperative infection would pose a serious hazard to the patient's recovery and well-being.

Microbial infections
Local wound infections (superficial or deep-sided), urinary tract infections (caused by bladder catheter, inserted for surgery), and pneumonia (due to impaired breathing/coughing, caused by sedation and analgesics during the first few hours of recovery) may endanger the health of patients after surgery. Visibly worse are postoperative bacterial infections at the site of implanted foreign bodies (sutures, ostheosynthetic material, joint replacements, pacemaker implants, ect). Often, the outcome of the procedure in question and even the life of the patient is at risk.

Prevention of microbial infection
Worldwide experience with antimicrobial prophylaxis in surgery has proven to be effective and cost-efficient, both avoiding severe patient suffering while saving lives (provided the appropriate antibiotics have been carefully chosen and used to the best of current medical knowledge).

Antibiotic selection
A proper regimen of antibiotics for perioperative prophylaxis of septic complications decreases the total amount of antimicrobials needed and eases the burden on hospitals. The choice of antibiotics should be made according to data on pharmacology, microbiology, clinical experience and economy. Drugs should be selected with a reasonable spectrum of activity against pathogens likely to be encountered, and antibiotics should be chosen with kinetics that will ensure adequate serum and tissue levels throughout the risk period.

For prophylaxis in surgery, only antibiotics with good tolerability should be used. Cephalosporins remain the preferred drugs for perioperative prophylaxis due to their low toxicity. Parenteral systemic antibiotics seem to be more appropriate than oral or topical antibiotics because the chosen antibiotics must reach high concentrations at all sites of danger. It is well recognized that broad-spectrum antibiotics are more likely to prevent gram-negative sepsis. New data demonstrate that third generation cephalosporins are more effective than first and second generation cephalosporins if all perioperative infectious complications are taken into consideration.

Duration of antibiotic administration
Prophylaxis of the shortest possible duration should be aimed at in order to minimize the risk of serious adverse effects or dangerous development of resistance. The minimum frequency of administration is the single dose, which usually produces fewer adverse effects than the multiple dosage and at the same time often represents the most economical form of administration.

The goal of antimicrobial prophylaxis is to achieve sufficient antibiotic tissue concentrations prior to possible contamination in the relevant tissues and to ensure adequate levels throughout the operative procedure to prevent subsequent bacterial growth. Of crucial importance for success in surgical prophylaxis is the timing of administration of short-acting antibiotics, as persistent antimicrobial activity throughout the entire operation is essential; the longer a surgical procedure lasts, the longer an appropriate antibiotic tissue level must be maintained. This can be achieved either by repeated administrations or by giving a single dose of a suitable long-lasting antimicrobial.

Also, by extending the antimicrobial cover some hours beyond the duration of the actual surgical procedure, it is possible to reduce the perioperative infection rates of urinary and respiratory septic complications considerably (provided an adequately broad spectrum antibiotic prophylaxis is chosen).

Advantages of long-acting antibiotics
Long-acting, broad-spectrum antibiotics offer the following advantages by comparison to short-acting antimicrobials in perioperative prophylaxis:
 * A single dose covers the whole perioperative risk period - even if the operation is delayed or long-lasting - and with regard to respiratory and urinary tract infections
 * Repeat administrations for prophylaxis are not necessary, so that additional doses are less likely to be forgotten (an advantage of practical value in a busy working situation such as a hospital)
 * Less risk of development of resistance and less side effects
 * Increased compliance and reduced errors of administration
 * Possibly better cost-effectiveness (less material and labor cost, less septic perioperative complications)

Resources

 * |Antimicrobial Therapy in Otolaryngology
 * Urinary track infection in adults Cleveland Clinic
 * Antimicrobial prophylaxis Virginia-Maryland Regional College of Veterinary Medicine