Prevention of gram negative bacillary pneumonia using aerosol polymyxin as prophylaxis. I. Effect on the colonization pattern of the upper respiratory tract of seriously ill patients

Abstract

A prospective study used polymyxin B by aerosol to reduce colonization of the upper respiratory tract with nosocomial gram negative bacilli. 58 high risk patients from the Respiratory Surgical Intensive Care Unit entered the trial. 33 were randomly selected to receive 2.5 mg/kg/day of polymyxin B by hand atomizer into the pharynx, and tracheal tube if present. 17 of 25 control patients became colonized with gram negative bacilli as compared with 7 of 33 polymyxin treated patients (p<0.01). Control patients became colonized with a total of 33 gram negative bacilli: 3 were P. aeruginosa, 21 were Enterobacteriaceae. The polymyxin treated patients became colonized with a total of 11 gram negative bacilli: no P. aeruginosa and only 3 species of Enterobacteriaceae were recovered. Colonization increased with duration in the Respiratory Surgical Intensive Care Unit and with time of required controlled ventilation. Polymyxin most effectively prevented the increase in colonization in treated patients who stayed in the Respiratory Surgical Intensive Care Unit for longer than 1 wk and who required controlled ventilation for at least 72 hr.