No abstract

Background: In ventilated patients already critically ill, isolation of Acinetobacter baumannii from lower respiratory tract may have clinical importance and the differentiation between infection and colonization can be difficult. Aim: We sought to overcome the confounding element of critical illness by using Simplified Acute Physiology score (SAPS II) to predict mortality risk and comparing this in critically ill ventilated patients between those with A. baumannii alone and those entirely negative lower respiratory tract cultures. Methods: 138 eligible cases from an urban-based tertiary hospital intensive care unit (ICU) were retrospectively reviewed. Results: Between 43 patients with A. baumannii [mean age (SD): 47 (18.5) yrs; 65% male] and 95 matched patients with negative cultures [51 (17.5); 53%], median risks of hospital mortality were not significant different but the median (IQR 25-75) length of total hospital stay [19 (11-32) vs. 14 (9-21) days, p=0.022] and ICU [8 (4-19) vs. 7 (3-9), p=0.010] were significantly longer in A. baumannii group. Such findings occur irrespective of whether the underlying lungs were diseased or not and whether the isolates were resistant (except for cefepime-resistance). Conclusion: Isolation of lower respiratory tract A. baumannii alone in critically ill patients is no more likely to cause increased mortality risk than in those with negative culture, and prolonged ICU stay is likely responsible for the acquisition of A. baumannii.