Comparison of pneumonia- and non-pneumonia-related Acinetobacter baumannii bacteremia: Impact on empiric therapy and antibiotic resistance

Objective: Acinetobacter baumannii (AB) bacteremia has increasingly emerged as a nosocomial pathogen in healthcare settings, associated with high patient morbidity and mortality. The objective of this study was to compare clinical features, risk factors, treatment outcome, and antibiotic resistance in patients with pneumonia- and non-pneumonia-related AB bacteremia. Methods: We conducted a retrospective study in a tertiary teaching hospital in northern Taiwan. The medical records of the 141 episodes of hospital-acquired AB bacteremia between July 1, 2006 and June 30, 2012 were reviewed, and sorted into groups of AB bacteremia with (n = 59) and without pneumonia (n = 82). Results: The hospital-acquired pneumonia-related AB bacteremia group were found to be significantly more frequently treated in intensive care units (49.2%, p <0.001), but the AB bacteremia without pneumonia group were significantly more frequently treated on general wards (85.4%, p <0.001). Patients with pneumonia tended to be older than the nonpneumonia group (72.8 years vs. 65.2 years in mean age, p <0.01), and more likely to use mechanical ventilators (62.7% vs. 15.9 %, p <0.001). Pneumonia patients were found to receive broad-spectrum antibiotics significantly earlier than nonpneumonia patients (p <0.001). Compared to those without pneumonia, the patients with pneumonia had significantly higher incidence of antibiotic-resistance (p <0.05), longer hospital stay (p <0.01), and higher mortality rate (p <0.001). The incidence of multidrug-resistant AB was significantly higher in patients with pneumonia (p <0.05), and only colistin (p <0.01) and tigecycline (p <0.01) were significantly active against multidrug-resistant AB isolates. Conclusion: Pneumonia-related AB bacteremia has a worse outcome, more antibiotic resistance, and more comorbidity than the nonpneumonia group.