Symposium on New Methods of Treatment of Gastrointestinal Disease
Perioperative Prophylactic Antibiotics in Abdominal Surgery A Review of Recent Progress
Douglas L. Hurley, M.D., Paxton Howard Jr., M.D., F.A.C.P, and H. Herbert Hahn, II, M.D., F.A.C.P.
The use of perioperative antibiotics to reduce the incidence of septic complications after abdominal and other surgical procedures became widespread in the decade following the discovery of antimicrobial agents. Their empiric use, however, did not significantly reduce infections and appeared to foster the development of resistant strains of organisms, and eventually the practice fell into disfavor. The difficulties with the earlier studies have been reviewed recently." 6,38 The pioneering experimental work of Burke" stimulated a number of wellcontrolled prospective clinical studies of perioperative antibiotic prophylaxis. Recent experimental studies of abdominal surgery in dogs have confirmed his original observations." An understanding of the normal flora of the gut has been critically important in the design of these studies. Since this subject was last discussed in the Surgical Clinics » several well controlled trials have established the safety and efficacy of either systemic or oral antimicrobial perioperative prophylaxis, and in several areas the question has become not "whether" but "how."13,47 Certain principles guiding the use of perioperative prophylactic antibiotics can be derived from these experimental and clinical studies. First, prophylactic antibiotics should be used only in those patients at From the Division of Infectious Diseases, Scott and White Clinic, Temple, Texas
Surgical Clinics of North America - Vol. 59, No.5, October 1979
919
920
DOUGLAS
L.
HURLEY ET AL.
high risk for postoperative infection. If a surgical procedure is known to have a usual infection rate several times higher than accepted rates for ." clean" procedures, or if the consequences of postoperative infection, such as infected vascular prostheses, are life-threatening, antibiotics may be useful with acceptable risks to the patient and the hospital environment. Second, a prophylactic antibiotic must be given in sufficient dose appropriate for the usual endogenous flora of the surgical area or for the expected exogenous pathogens. Third, systemic prophylactic antibiotics should be given only for the immediate perioperative period. This period has been generally found to be one to six hours preoperatively and no more than 24 to 48 hours postoperatively. Both experimental and clinical studies have shown that the most important determinative factor in postoperative infection is the presence of viable organisms in the surgical field at the time of wound closure. In addition, it has been clearly shown that antibiotics do not enter the wound once sealed with fibrin and that they exert no beneficial effect after this period. Prolonged administration merely increases the risks of colonization with more resistant organisms and produces a detrimental effect on the hospital bacterial flora. This paper reviews the recent studies in gastroduodenal, biliary, and colorectal perioperative antibiotic prophylaxis.
GASTRODUODENAL SURGERY Until recently the analysis of postoperative infectious complications of gastroduodenal surgery has been difficult because these procedures have been reported with multiple other abdominal procedures which are associated with varying risks. The rate of infectious complications associated with surgery in this area has generally been relatively low when compared with colorectal surgery. In the normal individual, gastric acid is produced in amounts which causes a pH unfavorable to the growth of most microorganisms. The lumen of the stomach is generally culturally sterile or organisms are recovered in smaller numbers than the inoculum (104 organisms) generally found to be necessary to induce wound infection in fresh experimental surgical wounds. 5• 36 Streptococci, staphylococci, and lactobacilli are the predominant organisms found in the upper gastrointestinal tract. Anaerobic and enteric bacteria, and fungi are rarely encountered." These observations explain the low rate of wound infections generally observed and mandate that this area of surgery be studied separately when antibiotic prophylaxis is considered. The statistics of combinations of low risk procedures and high risk procedures are not evaluable. Lewis has recently evaluated 444 gastric operations performed over a 10 year period from one institution and was able to define high risk and low risk gastroduodenal procedures. He was able to show that rate of wound infection of elective operations for intractable chronic duodenal ulcer (4.8 per cent) was not significantly different (p=0.3) from that of other refined clean operations in his institution. When
PERIOPERATIVE PROPHYLACTIC ANTIBIOTICS
921
other gastroduodenal surgical procedures were compared with this elective group, he found that rates of wound infection varied widely: emergency operation for gastroduodenal hemorrhage, 48.7 per cent (p
Perioperative Prophylactic Antibiotics in Abdominal Surgery A Review of Recent Progress
Douglas L. Hurley, M.D., Paxton Howard Jr., M.D., F.A.C.P, and H. Herbert Hahn, II, M.D., F.A.C.P.
The use of perioperative antibiotics to reduce the incidence of septic complications after abdominal and other surgical procedures became widespread in the decade following the discovery of antimicrobial agents. Their empiric use, however, did not significantly reduce infections and appeared to foster the development of resistant strains of organisms, and eventually the practice fell into disfavor. The difficulties with the earlier studies have been reviewed recently." 6,38 The pioneering experimental work of Burke" stimulated a number of wellcontrolled prospective clinical studies of perioperative antibiotic prophylaxis. Recent experimental studies of abdominal surgery in dogs have confirmed his original observations." An understanding of the normal flora of the gut has been critically important in the design of these studies. Since this subject was last discussed in the Surgical Clinics » several well controlled trials have established the safety and efficacy of either systemic or oral antimicrobial perioperative prophylaxis, and in several areas the question has become not "whether" but "how."13,47 Certain principles guiding the use of perioperative prophylactic antibiotics can be derived from these experimental and clinical studies. First, prophylactic antibiotics should be used only in those patients at From the Division of Infectious Diseases, Scott and White Clinic, Temple, Texas
Surgical Clinics of North America - Vol. 59, No.5, October 1979
919
920
DOUGLAS
L.
HURLEY ET AL.
high risk for postoperative infection. If a surgical procedure is known to have a usual infection rate several times higher than accepted rates for ." clean" procedures, or if the consequences of postoperative infection, such as infected vascular prostheses, are life-threatening, antibiotics may be useful with acceptable risks to the patient and the hospital environment. Second, a prophylactic antibiotic must be given in sufficient dose appropriate for the usual endogenous flora of the surgical area or for the expected exogenous pathogens. Third, systemic prophylactic antibiotics should be given only for the immediate perioperative period. This period has been generally found to be one to six hours preoperatively and no more than 24 to 48 hours postoperatively. Both experimental and clinical studies have shown that the most important determinative factor in postoperative infection is the presence of viable organisms in the surgical field at the time of wound closure. In addition, it has been clearly shown that antibiotics do not enter the wound once sealed with fibrin and that they exert no beneficial effect after this period. Prolonged administration merely increases the risks of colonization with more resistant organisms and produces a detrimental effect on the hospital bacterial flora. This paper reviews the recent studies in gastroduodenal, biliary, and colorectal perioperative antibiotic prophylaxis.
GASTRODUODENAL SURGERY Until recently the analysis of postoperative infectious complications of gastroduodenal surgery has been difficult because these procedures have been reported with multiple other abdominal procedures which are associated with varying risks. The rate of infectious complications associated with surgery in this area has generally been relatively low when compared with colorectal surgery. In the normal individual, gastric acid is produced in amounts which causes a pH unfavorable to the growth of most microorganisms. The lumen of the stomach is generally culturally sterile or organisms are recovered in smaller numbers than the inoculum (104 organisms) generally found to be necessary to induce wound infection in fresh experimental surgical wounds. 5• 36 Streptococci, staphylococci, and lactobacilli are the predominant organisms found in the upper gastrointestinal tract. Anaerobic and enteric bacteria, and fungi are rarely encountered." These observations explain the low rate of wound infections generally observed and mandate that this area of surgery be studied separately when antibiotic prophylaxis is considered. The statistics of combinations of low risk procedures and high risk procedures are not evaluable. Lewis has recently evaluated 444 gastric operations performed over a 10 year period from one institution and was able to define high risk and low risk gastroduodenal procedures. He was able to show that rate of wound infection of elective operations for intractable chronic duodenal ulcer (4.8 per cent) was not significantly different (p=0.3) from that of other refined clean operations in his institution. When
PERIOPERATIVE PROPHYLACTIC ANTIBIOTICS
921
other gastroduodenal surgical procedures were compared with this elective group, he found that rates of wound infection varied widely: emergency operation for gastroduodenal hemorrhage, 48.7 per cent (p
