The Effect of a Novel Regime of Selective Decontamination on the Incidence of Unit-Acquired Lower Respiratory Tract Infection in Mechanically Ventilated Patients
A prospective randomized study was performed to evaluate the effectiveness of selective decontamination (SDD) in combination with short-term systemic antimicrobial prophylaxis in patients requiring prolonged (at least five days) mechanical ventilation. After stratification by means of the APACHE II score, patients were randomly allocated to one of three groups. Patients in both control groups I (n = 18) and H (n = 21) did not receive antibiotic prophylaxis. However, in cases of infection, patients in group I received antibiotics which may affect indigenous flora, whereas those in group H received only antibiotics with no influence on colonization resistance. Patients in group III (n = 17) received SDD from admission until extubation. Our SDD regimen consisted of norfloxacin 50 mg, polymyxin E 200 mg and amphotericin B 500 mg q.i.d. via the gastric tube; a sticky paste containing 2% of the same antibiotics was applied to the oropharynx q.i.d. Group III patients further received intravenous antibiotic prophylaxis (cefotaxime 500 mg t.i.d.), during the first 5 days of admission. In both control groups about 90% of the patients acquired microbial colonization of oropharynx or stomach, lower respiratory tract infection occurred in 14 patients (78%) in group I and in 13 patients (62%) in group II. Microorganisms causing lower respiratory tract infection were mostly gram-negative bacilli originating from the oropharynx or stomach. In group III patients microbial colonization of the oropharynx and stomach was significantly reduced, and only one patient (6%) acquired lower respiratory tract infection, a highly significant reduction (p = 0.001).