Taxonomy and Identification of the Burkholderia cepacia Complex

Abstract

At the beginning of this review it is essential to clarify the terminology that will be used to refer to the members of the Burkholderia cepacia complex and their relatives.The name B. cepacia will relate only to B. cepacia genomovar I. Strains resembling B. cepacia may belong to the B. cepacia complex, to other Burkholderia species (for instance, Burkholderia gladioli), or to species from other genera (for instance, Ralstonia pickettii) that share some phenotypic or genotypic similarities with the B. cepacia complex.B. cepacia complex bacteria and organisms that may be confused with them will be altogether referred to as B. cepacia-like organisms.Most previous reports regarding these organisms were published before the recognition of the complicated taxonomic relationships between the different members of the B. cepacia complex; it is therefore unclear to what category the presumed B. cepacia isolates described would belong.For that reason, when such literature is cited, the name "B. cepacia" will be shown in double quotes.Chronic microbial colonization of the major airways, leading to exacerbations of pulmonary infection, is the major cause of morbidity and mortality in patients with cystic fibrosis (CF).Typical CF pathogens include Staphylococcus aureus, Pseudomonas aeruginosa, and Haemophilus influenzae (30).Other glucose nonfermenters, like Stenotrophomonas maltophilia, Alcaligenes xylosoxidans, R. pickettii, and Burkholderia gladioli, can frequently be found as well, but their role in the decline of pulmonary function is unclear (14,19,30).Several reports on the recovery of "B.cepacia" from CF patients appeared in the late 1970s and early 1980s (62,63).The first detailed description of the clinical significance of "B.cepacia" colonization and infection was published in 1984 (47).In that seminal paper, Isles et al. documented the increasing prevalence of "B.cepacia" colonization and infection in the Toronto, Canada, CF treatment center and described the so-called "cepacia syndrome," a severe progressive respiratory failure with bacteremia that occurs in about 20% of all infected CF patients.Clustering of new cases in some centers and the decrease of colonization of new patients following segregation of colonized and noncolonized patients in other centers suggested that "B.cepacia" could be transmitted between CF patients.This was confirmed by several studies (34,64,67,76,84,94) that showed