[Perioperative antimicrobial prophylaxis for colonic surgery: Present status in Germany. A prospective multicenter...

The objective of a multicentric observational study, that was performed in Germany between 1(st) September 1996 and 30(th) September 1997, was to assess postoperative infections as a function of risk factors and antibiotic prophylaxis under everyday clinical conditions. 2 481 patients from 114 centres who received infection prophylaxis prior to elective colonic resection were included. In the descriptive analysis of the study it was noted that 36.1 % of the patients had received no prophylaxis with metronidazole despite the fact that the study protocol recommended the use of this drug in preoperative antibiotic combinations. The present analysis therefore considers the influence of metronidazole on the postoperative infection rate.

In order to exclude any bias due to intergroup differences in risk profile, the groups with and without metronidazole were subjected to a matched-pair analysis. Matching parameters were: duration of operation, blood loss, age, diabetes mellitus, hepatic, renal, or chronic airways disease, immunosuppressive therapy, and rectal resection. This led to the formation of 800 pairs that were matched with respect to these parameters. The 800 pairs were then stratified into the following treatment groups: Group 1 a and b: long-acting cephalosporine (ceftriaxone) with or without metronidazole (n = 2 x 491); Group 2 a and b: short-acting cephalosporines with or without metronidazole (n = 2 x 133); Group 3 a and b: broad-spectrum penicillines with or without metronidazole (n = 2 x 176).

In all three treatment groups combination therapy with metronidazole was found to be significantly superior. Postoperative infection rates were 9.4 % and 18.7 % (p = 0.000) respectively in Group 1 a and b, 12.0 % and 25.6 % (p = 0.008) respectively in Group 2 a and b, and 19.9 % and 29.0 % (p = 0.009) respectively in Group 3 a and b.

Preoperative administration of metronidazole in addition to an effective beta-lactam antibiotic is strongly advised in elective colonic surgery, as absence of antibiotic cover against anaerobic colonic flora leads to a significantly higher postoperative infection rate.