Current guidelines for antibiotic prophylaxis of surgical wounds

Author: Ronald K. Woods, E. Patchen Dellinger
Date: June, 1998

Postoperative wound infections have an enormous impact on patients' quality of life and contribute substantially to the financial cost of patient care. The potential consequences for patients range from increased pain and care of an open wound to sepsis and even death. Approximately 1 million patients have such wound infections each year in the United States, extending the average hospital stay by one week and increasing the cost of hospitalization by 20 percent.[1] This translates to an additional $1.5 billion in health care costs annually.[2]

The occurrence of wound infection requires a local inoculum sufficient to overcome host defenses and establish growth. The process is complex and depends on the interaction of various host, local tissue and microbial virulence factors. Measures intended to prevent wound infection typically attempt to modify the host and local tissue factors and include, for example, preoperative optimization of comorbid illness, control of the operative environment, proper cleansing of the skin and use of aseptic surgical technique. Antibiotic prophylaxis is only one relatively minor effort among numerous preventive measures, but the efficacy and impact of antimicrobial prophylaxis has clearly been demonstrated to be significant.[3,4]

Historical Perspective

Attention to surgical wounds is exemplified historically by attending to gunshot wounds with a creechle of worms, rose oil and moss from the skull of a mummy collected at full moon (certain references indicate that this boiling concoction was incomplete without the addition of fresh puppies). Ambroise Pares use of egg yolk, rose oil and turpentine (not boiled) was regarded as progressive. In the 1600s, wound infection was so common that redness, warmth and purulence were thought to be desirable features of wound healing. Despite the documented efficacy of handwashing in reducing puerperal sepsis in the mid-1800s, which was introduced by Semmelweis and popularized by Holmes, the widespread practice of handwashing for the surgical team was not established until the early 20th century.

The practical source of the belief in "laudable pus" is likely based on the fact that only living patients produced pus. Major surgery was almost invariably followed by infectious complications, typified by erysipelas, rapidly progressive soft tissue infections (streptococcal or mixed synergistic infections) and tetanus. Associated mortality was high. The introduction of carbolic acid spray (used on the entire operating room, patient and surgeons) by Lister in 1867 led to a dramatic reduction in infection rates to less than 10 percent. Nevertheless, the "antiseptic principle" was. not widely accepted. Lister's results, however, fostered a context more accepting of Pasteur's theory of putrefaction: purulence was caused by microorganisms. After the adoption of handwashing and the use of sterile gloves, gowns and supplies (autodave), infection rates for clean procedures approached modern rates. However, infection rates for procedures of the gastrointestinal tract remained high as a result of the endogenous origin of the bacteria.

Following the introduction of antibiotics, early clinical trials in the 1950s reported either no benefit or a higher infection rate with antibiotic prophylaxis.[5-7] Moreover, the emergence of resistant strains was attributed, in part, to such use of antibiotics. Although a small number of authors supported the use of prophylactic antibiotics for "dirty" or contaminated cases, most did not recommend their use in cleaner cases.

Fortunately, studies by Burke in the early 1960s revealed the critical flaw in previous investigations and clinical failures.[8] Burke administered a single dose of penicillin systemically at various times before and after the inoculation of penicillin-sensitive Staphylococcus aureus in the dermis of guinea pigs. Administration of antibiotic either shortly before or after the inoculation of organisms resulted in lesions histologically identical to lesions induced by intradermal inoculation with killed organisms. Delaying the administration of antibiotic by as little as three hours resulted in lesions identical to those in animals not receiving antibiotics. The critical dependence of prophylactic efficacy on timing of administration was soundly established and subsequently shown to depend on the presence of peak antibiotic levels in the tissue at a time when the local concentration of microorganisms would otherwise be high. Subsequent investigation has focused on the delineation of specific procedures, prophylactic regimens and the optimization of efficacy.

Surgical Procedure Classification and Consideration of Specific Risk Factors

Establishing a "prophylaxis indicated" status for a given procedure requires consideration of the likelihood of infection without antibiotics and the morbidity and cost of an infectious complication. The discussion of these issues is facilitated by a taxonomy that classifies a procedure according to the level of microbial contamination routinely associated with that procedure and the likelihood of infection. Criteria are based on clinical information defined by the National Academy of Sciences, National Research Council (NRC), Division of Medicine, Ad Hoc Committee on Trauma.[9] The classification is provided in Table 1. The incidence of infection ranges widely across classes--less than 2 percent for clean procedures (e.g., breast biopsy) to over 40 percent for dirty procedures (colon perforation with diffuse fecal contamination). It is generally agreed that antibiotic prophylaxis is warranted in all procedures in the categories of clean-contaminated, contaminated or dirty.

TABLE 1 Classification of Operative Wounds and Risk of InfectionClassification Criteria Risk (%)Clean Elective, not emergency, < 2 nontraumatic, primarily closed; no acute inflammation; no break in technique; respiratory, gastrointestinal, biliary and genitourinary tracts not enteredClean-contaminated Urgent or emergency case that is < 10 otherwise clean; elective opening of respiratory gastrointestinal, biliary or genitourinary tract with minimal spillage (e.g., appendectomy) not encountering infected urine or bile; minor technique breakContaminated Nonpurulent inflammation; gross ~ 20 spillage from gastrointestinal tract; entry into biliary or genitourinary tract in the presence of infected bile or urine; major break in technique; penetrating trauma < 4 hours old; chronic open wounds to be grafted or coveredDirty Purulent inflammation (e.g., ~ 40 abscess); preoperative perforation of respiratory, gastrointestinal, biliary or genitourinary tract; penetrating trauma > 4 hours old

Information from Cruse PJ, Foord R. The epidemiology of wound infection. A 10-year prospective study of 62,939 wounds. Surg Clin North Am 1980;60:27-40.

The argument against prophylaxis for clean procedures, based on the intrinsically low rate of infection without antibiotic treatment, is overly simplistic for several reasons. For specific clean procedures, infection may be unlikely, but the morbidity and cost of even infrequent infection can justify the use of prophylaxis. An example is the insertion of prosthetic devices, such as heart valves or joints. Also, clean procedures constitute approximately 60 percent of all surgical procedures and account for approximately 40 percent of all wound infections.[10] It is estimated that prophylaxis for clean procedures would reduce the overall incidence of wound infection by 17 percent.[11]

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[25.] Kaiser AB, Herrington JL Jr, Jacobs JK, Mulherin JL Jr, Roach AC, Sawyers JL. Cefoxitin versus erythromycin, neomycin, and cefazolin in colorectal operations. Importance of the duration of the surgical procedure. Ann Surg 1983;198:525-30.

[26.] Clarke JS, Condon RE, Bartlett JG, Gorbach SL, Nichols RL, Ochi S. Preoperative oral antibiotics reduce septic complications of colon operations: results of prospective, randomized, double-blind clinical study. Ann Surg 1977;186(3):251-9.

[27.] Baum ML, Anish DS, Chalmers TC, Sacks HS, Smith H Jr, Fagerstrom RM. A survey of clinical trials of antibiotic prophylaxis in colon surgery: evidence against further use of no-treatment controls. N Engl J Med 1981;305:795-9.

[28.] Stellato TA, Danziger LH, Gordon N, Hau T, Hull CC, Zollinger RM Jr, et al. Antibiotics in elective colon surgery. A randomized trial of oral, systemic, and oral/systemic antibiotics for prophylaxis. Am Sung 1990;56:251-4.

[29.] Solla A Rothenberger DA. Preoperative bowel preparation. A survey of colon and rectal surgeons. Dis Colon Rectum 1990;33:154-9.

[30.] Hemsell DL. Prophylactic antibiotics in gynecologic and obstetric surgery. Rev Infect Dis 1991;13(Suppl 10):S821-41.

[31.] Pitt HA, Postier RG, MacGowar AW, Frank LW, Surmak AJ, Sitzman JV, et al. Prophylactic antibiotics in vascular surgery. Topical, systemic, or both? Ann Sung 1980,192:356-64.

[32.] Kaiser AB, Clayson KR, Mulherin JL Jr, Roach AC, Allen TR, Edwards WH, et al. Antibiotic prophylaxis in vascular surgery. Ann Surg 1978; 188:283-9.

[33.] Platt R, Zucker JR, Zaleznik DF, Hopkins CC, Dellinger EP, Karchmer AW, et al. Prophylaxis against wound infection following herniorrhaphy or breast surgery. J Infect Dis 1992;166:556-60.

This article was written at the request of the infectious Diseases Society of America.

RONALD K. WOODS, M.D., is a fifth-year resident in surgery at the University of Washington. He completed a Ph.D. in biophysics at the University of Illinois College of Medicine Medical Scholars Program, Champaign-Urbana, where he also received his medical degree.

E. PATCHEN DELLINGER, M.D., is professor and vice-chair of surgery, chief of the division of general surgery, and associate medical director of the University of Washington Medical Center, Seattle. He received his medical degree from Harvard Medical School, Boston, and completed a surgical residency at Beth Israel Hospital, Boston, and a fellowship in infectious diseases at Tufts-New England Medical Center, Boston.

Address correspondence to E. Patchen Dellinger M.D., Department of Surgery Box 356470, University of Washington Medical Center 1959 N,E. Pacific St., Seattle, WA 98195-6410. Reprints are not available from the authors.

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