Frequency of colonization and pneumonia and development of resistance in long-term ventilated intensive-care patients subjected to selective decontamination of the digestive tract

Colonization of the oropharynx with potentially pathogenic microorganisms (PPM) is a highly significant factor in the pathogenesis of bacterial pneumonia in intensive care patients. Via colonization of the oropharynx, bacteria pass into the tracheobronchial tree, where they can give rise to pneumonia after overcoming pulmonary resistance mechanisms. By a new, prophylactic antibiotic treatment schedule consisting in selective decontamination of the digestive tract (SDD) with locally applied nonabsorbable antibiotics, Stoutenbeek achieved drastic lowering of the colonization and infection rate in trauma patients. In the present study, we wanted to check whether this new prophylactic antibiotic schedule can be applied on a surgical intensive care ward in all patients with long-term ventilation, irrespective of the diagnosis, and whether it affords advantages over a conventional antibiotic schedule. MATERIALS AND METHODS. All patients on a surgical intensive care ward in whom it was expected that mechanical ventilation would be necessary for more than 4 days were included in the study. During the first 6 months 83 patients were investigated, in whom antibiotics were only administered when the presence of infection had been confirmed, in accordance with generally accepted guidelines (control group). In the second 6-month period, 82 patients were selectively decontaminated with 4 x 100 mg polymyxin E, 4 x 80 mg tobramycin and 4 x 500 mg amphotericin B, administered through the gastric tube and in an antimicrobial paste in the oropharynx (SDD group). The SDD schedule entailed systemic administration of cefotaxime in the first 3-4 days. RESULTS. In the control group, enterobacteria/Pseudomonas spp. were isolated significantly more frequently than in the SDD group (P less than 0.001): in the pharyngeal smear in up to 53%, in the tracheal secretion up to 36%, and in the rectal smear in up to 93% of the patients In the SDD group in the 1 week the frequency of gram-negative aerobic bacteria in the pharynx decreased from 33% to 5%, in the tracheal secretion from 23% to 14% and in the rectum from 86% to 52% (24% in the second week). However, the decrease in gram-negative microorganisms was accompanied by significant increase in the frequency of Staphylococcus epidermidis and enterococci. The SDD schedule proved to be effective with regard to the rate of infection. In the control group, 35 patients developed pneumonia (42%) as against 5 patients receiving SDD prophylaxis (6%). The duration of mechanical ventilation in the patients with pneumonia was 5 days longer than in patients without pneumonia.(ABSTRACT TRUNCATED AT 400 WORDS)