Clinical and epidemiological features of Chryseobacterium indologenes infections: Analysis of 215 cases

This study investigates the clinical and epidemiological features of Chryseobacterium indologenes infections and antimicrobial susceptibilities of C indologenes.With 215 C indologenes isolates between January 1, 2004 and September 30, 2011, at a medical center, we analyzed the relationship between the prevalence of C indologenes infections and total prescription of colistin and tigecycline, clinical manifestation, antibiotic susceptibility, and outcomes.Colistin and tigecycline were introduced into clinical use at this medical center since August 2006. The increasing numbers of patients with C indologenes pneumonia and bacteremia correlated to increased consumption of colistin (p = 0.018) or tigecycline (p = 0.049). Among patients with bacteremia and pneumonia, the in-hospital mortality rate was 63.6% and 35.2% (p = 0.015), respectively. Administration of appropriate antibiotics showed significant benefit in 14-day survival in patients with C indologenes bloodstream infection (p = 0.040). In bacteremic patients, old cardiovascular accident (p = 0.036) and cancer (p = 0.014) were the most common comorbidity. The most common co-infection pathogen in patients with C indologenes pneumonia was Acinetobacter baumannii (36/91, 39.6%), followed by Pseudomonas aeruginosa (23/91, 25.3%), carbapenem-resistant A baumannii (22/91, 24.2%), and Klebseilla pneumoniae (13/91, 14.3%). Antimicrobial susceptibility testing of the 215 isolates showed that trimethoprim-sulfamethoxazole was the most active agent (susceptibility rate: 87.4%), followed by cefoperazone-sulbactam (48.0%).The present study showed a trend of increasing prevalence of C indologenes infection after introduction of colistin and tigecycline usage. The bacteremia group had higher mortality rate than the pneumonia group. Increasing resistance to piperacillin-tazobactam, ceftazidime, cefepime, and newer fluoroquinolone were noticed in our analysis. Trimethoprim-sulfamethoxazole was a potential antimicrobial agent in vitro for C indologenes. To avoid collateral damage, we emphasize the importance of antibiotic stewardship program.