Genomic insights into efflux-mediated biofilm persistence and multidrug resistance in Achromobacter xylosoxidans from cystic fibrosis.

Achromobacter xylosoxidans is an emerging opportunistic pathogen related to cystic fibrosis (CF). Its clinical impact is variable among patients depending on strain-specific genomic diversity and interaction with co-infecting pathogens. Hence, genomic analysis plays a key role in understanding its pathogenic potential and adaptation in the CF disease. This study included a clinical strain isolated from sputum of a patient with CF. The strain was evaluated for its antimicrobial susceptibility using VITEK 2 and biofilm formation / inhibition using crystal violet assay in the presence and absence of PAβN. Whole-genome sequencing was conducted using Illumina technology, followed by genome assembly and annotation. The resistome and virulence profiling of MICB25 was achieved using BV-BRC and PGAP pipelines. The clinically strain (MICB25) was identified as Achromobacter xylosoxidans. Our study shows that secretion systems, multidrug efflux systems are functionally linked to biofilm formation in a CF-associated A. xylosoxidans MICB25, as evidenced by PAβN-mediated biofilm inhibition. The whole-genome sequencing revealed a multifaceted resistome including β-lactamases, aminoglycoside-modifying enzymes, and other resistance determinants in addition to an exceptionally broad and varied efflux repertoire covering ABC, MFS, RND, and SMR families. The application of whole-genome sequencing in this study provides crucial insights into the persistence-oriented pathogenic strategy of this emerging CF pathogen A. xylosoxidans. The coexistence of multidrug efflux determinants and PAβN-sensitive biofilm formation suggests that efflux activity could be involved in persistence and warrants addditional mechanistic investigation.