Effectiveness of selective digestive tract decontamination to control an outbreak of nosocomial pneumonia caused by Pseudomonas aeruginosa in mechanically ventilated patients

Abstract

The use of selective digestive tract decontamination (SDD) to reduce the endemic nosocomial pneumonia (NP) rate in intensive care unit (ICU) patients is well established although it has still not been widely endorsed. In addition, SDD appears to be effective in controlling outbreaks of nosocomial infection (NI), although this warrants further evaluation. This study was thus designed to evaluate the potential role of SDD in controlling an outbreak of NP due to Pseudomonas aeruginosa occurring in mechanically ventilated patients. In an initial four-month period, there was an abnormally high incidence (56%: 14 of 25 mechanically ventilated patients) of NP due to P. aeruginosa. A diagnosis of NP was based on the association of clinical criteria with a positive quantitative culture of a protected distal bronchoalveolar sample yielding a bacterial concentration ≥10 3 CFU/ml. In the subsequent four-month period, there was a systematic daily administration of an SDD regimen based upon neomycin, colistin and oropharyngeal application of povidone-iodine to all patients receiving mechanical ventilation (MV) for more than 48 hours throughout their ICU stay (Group 2, n=20). Demographic and baseline characteristics of patients in both groups were comparable. The groups were also similar with respect to the severity of acute illness and medical condition. Only one episode (5%) of NP due to P. aeruginosa occurred in Group 2 (p<0.02). The rate of NP due to other microorganisms was similar in the two groups (24% in Group 1 versus 25% in Group 2). The mean duration of MV was shorter in Group 2, as was stay in the ICU: 7.8±4 versus 17±12 days, p=0.03, and 12.7±6 versus 25.4±20 days, p=0.02, respectively. Mortality rates were similar in both groups (40%). We conclude that SDD devoted to control an abnormally high rate of NP due to P. aeruginosa in mechanically ventilated patients was effective. Accordingly, a short-term trial of SDD could be recommended when traditional infection control measures have failed.