Insights into the genome diversity and virulence of two clinical isolates of Burkholderia cenocepacia.

PURPOSE

Burkholderia cenocepacia is among the most common members of the Burkholderia cepacia complex (Bcc) isolated from patients with cystic fibrosis (CF). The factors triggering the high rates of morbidity and mortality in CF patients are not well elucidated. In this study, we aim to highlight the genome diversity of two clinical isolates of B. cenocepacia through comparative genome analysis.

METHODOLOGY

The repertoire of virulence factors and resistance genes compared to reference strains J2315 and K56-2 was elucidated. The isolates were screened for the presence of phages and insertion sequences. Two methods were combined to obtain an accurate prediction of genomic islands (GIs): the cumulative GC profile and the IslandViewer web tool. To study evolutionary relatedness, whole genome-based single-nucleotide polymorphism (wgSNP) analysis was also performed with 43 publically available strains of the Bcc of various sequence types.Results/Key findings. Genome-based species identification of the two isolates BC-AUH and BC-BMEH confirmed the species as B. cenocepacia. Both belonged to ST-602, a double-locus variant of ST-32 (CC31), genomovar IIIA, and carried a large number of antibiotic resistance genes. Eighteen GIs were predicted in BC-AUH and BC-BMEH, occupying 9.3 and 6.1 % of the respective genomes. Comparison to J2315 revealed 89 and 85 genes unique to BC-BMEH and BC-AUH, respectively. Additionally, 1823 intergenic SNPs were detected between BC-BMEH and BC-AUH.

CONCLUSION

This study mapped existing genetic variations in B. cenocepacia associated with notorious outcomes in CF patients, and the data obtained provide comprehensive, genome-inferred insights and multifactorial examination of an important human pathogen.