Predictive value of the serum bactericidal test for mortality in patients infected with multidrug-resistant Acinetobacter baumannii

Objective: Strains of Acinetobacter baumannii resistant to all available antibiotics except polymyxin B have circulated in Taiwan since 1998 and have caused a variety of nosocomial infections. There are no standard tests to measure outcome in patients infected with these strains. Our aim was to determine whether a serum bactericidal test (SBT) could be used for this purpose. Methods: This SBT was performed in 57 infected patients. Results: Among the 35 patients who survived and 22 patients who died, peak SBT titer negatively correlated with mortality rate (correlation coefficient -0.43). The survival rate in patients with a peak SBT titer ≧1:16, ≧1:8, and ≦1:4 was 100%, 87.5%, and 42.4%, respectively (p = 0.001). Mortality was found to be closely related to illness severity and the presence of multiple organ failure. In subgroup analysis, the power of SBT to predict mortality was significant for patients without multiple organ failure (p = 0.004), and also patients without disease defined as rapidly fatal by McCabe classification (p = 0.044). Conclusion: In a region with few therapeutic options for multi-drug resistant Acinetobacter baumannii (MDRAB), such as in Taiwan, SBT could be used as a prognosis indicator and indicator of the need to modify treatment in patients infected with MDRAB. ? 2007 The British Infection Society.