Antimicrobial therapy of infections following abdominal surgery

Even with excellent surgical technique, the infection rate after abdominal surgery is as high as 30%. One third of these infections extend to septicaemia. Successful therapy of septicaemia depends on early clinical suspicion, rigorous diagnostic measures, aggressive initiation of antimicrobial treatment and comprehensive supportive care. The bacteriology of postoperative, abdominal infections is dominated by aerobic and aerobic Gram-negative bacilli. Anaerobic bacteria are more prevalent in infections originating from sites with a faecal flora. Bacteroides fragilis is the most frequently isolated anaerobe. Enterococci are seldom the primary pathogen and polymicrobial etiology is common. Ideally, antimicrobial therapy should be tailored on the basis of an established, bacteriological diagnosis. In such cases, betalactam antibiotics should be preferred to aminoglycosides for toxicological and other reasons. In cases of unknown bacteriological etiology, a broad spectrum is required, and combinations of 2 or 3 antibiotics are recommended. In these combinations aminoglycosides play a dominant role. In abdominal infections, it is probably more favourable to combine an aminoglycoside with clindamycin than with benzyl-penicillin, even though the possibility of enterococci is not covered. In case of septicaemia where faecal contamination is strongly suspected, many clinicians feel that a triple combination with an aminoglycoside, benzyl-penicillin and an imidazole drug should be recommended.