Clinical and epidemiological features of Chryseobacterium indologenes infections: analysis of 215 cases.

Purpose: This study investigates the clinical and epidemiological features of Chryseobacterium indologenes infections and antimicrobial susceptibilities of C indologenes.

Methods: 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.

Results: 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%).

Conclusion: 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.