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Volume 48, Number 5, October 2015

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   

 

Corresponding author:

 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.



 

Background and purpose: 

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



 

Methods:

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. 



 

Results:

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. 



 

Conclusion:

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. 



 

Key words:

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