Predictors of mortality in Acinetobacter baumannii bacteremia

Hsin-Pai Chen¹, Te-Li Chen¹, Chung-Hsu Lai¹, Chang-Phone Fung¹, Wing-Wai Wong¹, Kwok-Woon Yu², Cheng-Yi Liu^1
1Section of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei; and ²Department Pathology and Laboratory Medicine, National Yang-Ming University, Taipei, Taiwan

Received: May 13, 2004 Revised: June 21, 2004 Accepted: July 30, 2004

Corresponding author: Dr. Chang-Phone Fung, Section of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, 201, Shih-Pai Road, Section 2, Taipei 11217, Taiwan. E-mail:

This study retrospectively investigated 149 episodes of Acinetobacter baumannii bacteremia which occurred during a 41-month period from September 1997 to January 2001. Bacteremia was nosocomial in 139 (93%) of the episodes and community-acquired in 10 (7%). Thirty three deaths (22.1%) were attributed to these episodes of A. baumannii bacteremia. The mean age of survivors was younger than that of patients who died of bacteremia (60.4 19.9 vs 67.1 17.4) but this result was not significant on univariate analysis (p=0.084). Previous intensive care unit stay was longer among survivors than among patients who died of bacteremia (9.5 vs 18 days, p=0.048). Factors associated with mortality included immunosuppression (p=0.019), shock (p=0.002), recent surgery (p=0.008), invasive procedures such as central venous catheterization (p=0.002), urinary catheterization (p=0.012), placement of a nasogastric tube (p<0.001), pulmonary catheterization (p=0.015), and mechanical ventilation (p=0.035). The number of underlying conditions (p=0.015) and invasive procedures (p<0.001) were positively correlated with mortality. Mortality was significantly associated with lower platelet count (p=0.001) and lower serum albumin concentration (p=0.005). Patients with catheter-related bacteremia had a high survival rate (96.2%), while survival rate was low in patients with infection originating from the respiratory tract (60.8%). Susceptibility testing by agar dilution test indicated that imipenem was the most effective antibiotic, followed by cefepime and ciprofloxacin. The mortality rate was lower in patients who received 1 or more antibiotics to which the isolates were susceptible, but this difference was not significant (p=0.197). On multivariate analysis, factors that independently correlated with mortality were increased age (p=0.003), immunosuppressive status (p=0.001), recent surgery (p=0.002), acute respiratory failure (p=0.004), acute renal failure (p=0.009) and septic shock (p<0.001). These findings highlight the importance of a treatment strategy based on risk stratification among patients with A. baumannii bacteremia.

Key words: Acinetobacter baumannii, bacteremia, mortality, retrospective studies, risk factors

J Microbiol Immunol Infect2005;38:127-136.