Impact of inappropriate empiric antimicrobial therapy on outcome in Pseudomonas aeruginosa bacteraemia: a stratified analysis according to sites of infection

The purpose of this study was to evaluate the impact of inappropriate empiric antimicrobial therapy on the outcome of Pseudomonas aeruginosa bacteraemia according to the primary infection site. A retrospective cohort study including 202 patients with P. aeruginosa bacteraemia was performed. High-risk sites of infection were defined as the lung, intra-abdominal non-hepatobiliary tract or unknown source. Of the 202 patients with P. aeruginosa bacteraemia, 80 (39.6%) had received inappropriate empiric antimicrobial therapy. No significant difference in the 30-day mortality rate was found between the inappropriate therapy group and the appropriate therapy group (19/80 [23.8%] vs. 32/122 [26.2%], P = 0.692). Patients with pneumonia or non-hepatobiliary tract intra-abdominal infection showed significant association with high mortality, while those with urinary tract or hepatobiliary tract infection showed negative associations with mortality. In the subgroup analysis including 98 patients with high-risk sites of infection, the mortality rate of the inappropriate therapy group was significantly higher than that of the appropriate therapy group (14/26 [53.8%] vs. 23/72 [31.9%], P = 0.035). Inappropriate empiric antimicrobial therapy was also found to be one of the independent risk factors for mortality in patients with high-risk sites of infection (odds ratio [OR] 8.69; 95% confidence interval [CI] 1.86-40.59), along with renal disease, corticosteroid use, polymicrobial infection and higher Pitt bacteraemia score. Inappropriate empiric antimicrobial therapy adversely affected the outcome of P. aeruginosa bacteraemia in patients with high-risk sites of infection. Our data suggest that the impact of inappropriate antimicrobial therapy on the outcome of P. aeruginosa bacteraemia may be dependent on the primary site of infection.