Chryseobacterium spp
, a new opportunistic pathogen associated with cystic fibrosis?. There is an increase in the isolation of non-fermenting gramnegative bacilli in patients with cystic fibrosis (CF). The present study evaluates the frequency of isolates of Chryseobacterium spp., analyzing its characteristics, resistance patterns and clinical outcome of patients. It has been collected all respiratory isolates of Chryseobacterium spp. of patients attended in the CF unit of Hospital de la Princesa for three years (march 2009-march 2012). For phenotypic and genotypic identification and sensitivity study conventional methodology was used. For the assessment of the patients lung function was considered the forced expiratory volume in one second (FEV1) and the results were analyzed with SPSS. There was an increase in the incidence of Chryseobacterium spp. with 17 isolates from 9 patients. Three patients had chronic colonization by this microorganism and one showed significant impairment of lung function. Seven patients showed also colonization with Staphylococcus aureus and 4 of them with Pseudomonas aeruginosa. Chryseobacterium spp. should be considered as a new emerging opportunistic pathogen in patients with CF. It is essential the clinical and microbiological monitoring of this group of patients for detection of Chryseobacterium spp. colonization and to prevent the chronic infection. In these circumstances it must assess its possible eradication, though its clinical impact is unknown. Cotrimoxazole being the best treatment option.