PREVENTION OF GRAM-NEGATIVE NOSOCOMIAL BRONCHOPNEUMONIA BY INTRATRACHEAL COLISTIN IN CRITICALLY ILL PATIENTS - HISTOLOGIC AND BACTERIOLOGICAL STUDY

Objective: To evaluate the efficiency of intratracheal colistin in pre venting nosocomial bronchopneumonia (BPN) in the critically ill. Desig n: Study evaluating the clinical incidence of nosocomial BPN in 2 grou ps of critically ill patients who receive or did not receive intratrac heal colistin. BPN was assessed clinically in survivors and histologic ally in non-survivors. Setting: A 14-bed surgical intensive care unit. Patients: 598 consecutive critically ill patients were studied during a prospective non-randomized study over a 40-month period. Interventi ons: 251 patients - 31 non-survivors and 220 survivors - did not recei ve intratracheal colistin and 347 - 42 non-survivors and 305 survivors - received intratracheal colistin for a 2-week period (1600000 units per 24 h). Measurements and results: The incidence of nosocomial BPN w as evaluated clinically in survivors, using repeated protected minibro nchoalveolar lavages, and histologically in non-survivors via an immed iate postmortem pneumonectomy (histologic and semi-quantitative bacter iologic analysis of one lung). The clinical incidence of nosocomial BP N was of 37% in coli (-) survivors and of 27% in coli (+) survivors (p <0.01). This result was histologically confirmed in non-survivors, whe re the incidence of histologic BPN was of 61% in coli (-) patients and of 36% in coli (+) patients (p<0.001). Emergence of BPN due to colist in-resistant micro-organisms was not observed. Because colistin was su ccessful in preventing Gram-negative BPN and did not change the absolu te number of Gram-positive BPN, the proportion of BPN caused by staphy lococcus species was higher in group coli (+) patients (33% vs 16%). M ortality was not significantly influenced by the administration of col istin. Conclusion: This study suggests that the administration of intr atracheal colistin during a 2-week period significantly reduces the in cidence of Gram-negative BPN without creating an increasing number of BPN due to colistin-resistant micro-organisms.