Abstract
The objective of the present study was to provide an updated classification for Burkholderia cepacia complex (Bcc) taxon K isolates. A representative set of 39 taxon K isolates were analyzed through multilocus sequence typing (MLST) and phylogenomic analyses. MLST analysis revealed the presence of at least six clusters of sequence types (STs) within taxon K, two of which contain the type strains of Burkholderia contaminans (ST-102) and Burkholderia lata (ST-101), and four corresponding to the previously defined taxa Other Bcc groups C, G, H and M. This clustering was largely supported by a phylogenomic tree which revealed three main clades. Isolates of B. contaminans and of Other Bcc groups C, G, and H represented a first clade which generally shared average nucleotide identity (ANI) and average digital DNA-DNA hybridization (dDDH) values at or above the 95–96% ANI and 70% dDDH thresholds for species delineation. A second clade consisted of Other Bcc group M bacteria and of four B. lata isolates and was supported by average ANI and dDDH values of 97.2 and 76.1% within this clade and average ANI and dDDH values of 94.5 and 57.2% toward the remaining B. lata isolates (including the type strain), which represented a third clade. We therefore concluded that isolates known as Other Bcc groups C, G, and H should be classified as B. contaminans, and propose a novel species, Burkholderia aenigmatica sp. nov., to accommodate Other Bcc M and B. lata ST-98, ST-103, and ST-119 isolates. Optimized MALDI-TOF MS databases for the identification of clinical Burkholderia isolates may provide correct species-level identification for some of these bacteria but would identify most of them as B. cepacia complex. MLST facilitates species-level identification of many taxon K strains but some may require comparative genomics for accurate species-level assignment. Finally, the inclusion of Other Bcc groups C, G, and H into B. contaminans affects the phenotype of this species minimally and the proposal to classify Other Bcc group M and B. lata ST-98, ST-103, and ST-119 strains as a novel Burkholderia species is supported by a distinctive phenotype, i.e., growth at 42°C and lysine decarboxylase activity.
Highlights
The Burkholderia cepacia complex (Bcc) is a group of closely related bacteria that occur naturally in a wide variety of ecological niches and that possess a remarkably versatile metabolism (Coenye et al, 2001; Parke and Gurian-Sherman, 2001; Depoorter et al, 2016; Kunakom and Eustáquio, 2019)
Among Bcc bacteria, taxon K became wellknown as a notorious contaminant of pharmaceutical products (Torbeck et al, 2011; Cunningham-Oakes et al, 2020; Tavares et al, 2020)
The present study was initiated to clarify the unresolved taxonomy of taxon K bacteria but revealed many borderline values which prevented a straightforward interpretation of data
Summary
The Burkholderia cepacia complex (Bcc) is a group of closely related bacteria that occur naturally in a wide variety of ecological niches and that possess a remarkably versatile metabolism (Coenye et al, 2001; Parke and Gurian-Sherman, 2001; Depoorter et al, 2016; Kunakom and Eustáquio, 2019). B. contaminans can be considered an emerging CF pathogen; it is the most common Bcc species in CF patients in Argentina (Cipolla et al, 2018) and it is increasingly isolated in CF centers in Spain (Medina-Pascual et al, 2015), the United Kingdom (Kenna et al, 2017), Portugal (Coutinho et al, 2015), and Ireland (Power et al, 2016) These organisms are frequently responsible for outbreaks of healthcareassociated infections due to contamination of pharmaceutical products such as nasal spray (CDC, 2004), dialysis water (Souza et al, 2004), moist washcloths (Martin et al, 2011), mouthwash (Zurita et al, 2014), and liquid docusate laxative (Glowicz et al, 2018)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
