Identification, epidemiological relatedness, and biofilm formation of clinical Chryseobacterium indologenes isolates from central Taiwan 

Yi-Cheng Chang, Hsueh-Hsia Lo, Hsiu-Ying Hsieh, Shan-Min Chang


Received: September 2, 2013    Revised: March 27, 2014    Accepted: April 1, 2014   

 Hsueh-Hsia Lo, Corresponding author. Department of Medical Laboratory Science and Biotechnology, Central Taiwan University of Science and Technology, Number 666, Buzi Road, Taichung 40601, Taiwan.

The clinical impact of Chryseobacterium indologenes infection is increasing; nevertheless, most studies had been conducted in northern Taiwan, but rarely in central Taiwan. 

Using 16S rRNA gene sequencing, 34 isolates of C. indologenes were identified at the Central Region Hospital Alliance between 2007 and 2011. Vitek 2 and matrix-assisted laser desorption ionization–time-of-flight mass spectrometry (MALDI–TOF MS) methods were compared for the feasibility to identify this bacterium. Drug susceptibility test, biofilm formation, and pulsed-field gel electrophoresis (PFGE) were also performed. 

All isolates were collected from hospitalized patients with an average age of 70.8 ± 18.5years. The most prevalent sample was urine (50.0%), followed by sputum (32.4%). The accuracy rate of species-level identification reached 94.1% using the Vitek 2 method and 85.3% using the MALDI–TOF MS method. All of the isolates were resistant to gentamicin, amikacin, ceftriaxone, chloramphenicol, colistin, and imipenem, but completely susceptible to minocycline. While analyzing biofilm-forming ability, 38.2% (13/34) of C. indologenes isolates displayed a positive phenotype using the Luria–Bertani (LB) medium. However, 80.0% (4/5) of invasive isolates were biofilm producers. Based on PFGE analysis, several clusters were found, and the possible intrahospital spread of this bacterium in this area could not be excluded. 

Both Vitek 2 and MALDI–TOF MS methods showed good ability in the determination of C. indologenes. Among the examined drugs, minocycline was the most potent one. As many as 38.2% C. indologenes isolates showed biofilm-forming ability. PFGE analyses revealed the possible intrahospital transmission of this bacterium in central Taiwan. 

Biofilm, Central Taiwan, Chryseobacterium indologenes, Epidemiological relatedness, Identification