Figure 1. Increased susceptibility to A. baumannii infection in aged mice. Young (n = 10) and aged mice (n = 10) were infected intratracheally with 5×106 CFU of LAC-4. (A) Clinical score and (B) survival rate of mice were monitored for 7 days. Clinical score is expressed as means ± SEM. The data represent one of 2 independent experiments. Survival curves were compared using log-rank test. Statistical significance of clinical score was determined by Student’s t test. **, P < 0.01.