[Preventive antibiotics in elective colorectal surgery]

At least every third patient undergoing elective colorectal surgery without antibiotic cover will develop one or more postoperative infectious complications. Using appropriate antimicrobial prophylaxis with agents effective against both aerobe and anaerobe microorganisms less than 4 per cent of the patients will have such problems. Systemic (i.v.) prophylaxis started immediately before or at induction of anaesthesia is the preferred method, giving maximal tissue concentrations of the agents during the contamination process. Short term prophylaxis, at least as effective as 5 days prophylaxis, will reduce toxicity, cost and resistance problems. Using agents with long half-lives (for instance doxycycline and tinidazole) single-dose prophylaxis is sufficient. Clinical resistance problems or reduced efficacy could not be demonstrated even after 10 years routine use of these agents in prophylaxis. Antibiotics necessary for treatment of serious infections should not be used in routine prophylaxis. Nitroimidazoles (metronidazole, tinidazole) represent an exception since development of resistance to these agents is extremely rare.