Biology subjects

Billiot, C. E.

Publications and source records attributed to Billiot, C. E..

3 recordsLinked to original sources

bioRxiv2023

Comparative genomics of clinical Stenotrophomonas maltophilia isolates reveals regions of diversity which correlate with colonization and persistence in vivo

Stenotrophomonas maltophilia is a Gram-negative emerging opportunistic pathogen often found in respiratory diseases such as cystic fibrosis (CF). Patients with CF experience lifelong polymicrobial infections of the respiratory mucosa. Our prior work showed that P. aeruginosa promotes persistence of S. maltophilia mouse respiratory infections. As is typical for environmental opportunistic pathogens, S. maltophilia has a large genome and a high degree of genetic diversity. In this study, we evaluated the genomic content of S. maltophilia, combining short and long read sequencing to construct complete genomes of 10 clinical isolates which were then compared with the larger phylogeny of S. maltophilia genomic sequence data, and compared colonization/persistence in vivo, alone and in coinfection with P. aeruginosa. We found that while the overall genome size and GC content were fairly consistent, there was considerable variability in arrangement and gene content. Similarly, there was significant variability in S. maltophilia colonization and persistence in vivo in experimental mouse respiratory infection. Ultimately, this study gives us a greater understanding of the genomic diversity of S. maltophilia isolated from patients, and how this genomic diversity relates to interactions with other pulmonary pathogens, and to host disease progression. Identifying the molecular determinants of infection with S. maltophilia can facilitate development of novel antimicrobial strategies for a highly drug-resistant pathogen.

microbiology↗

bioRxiv2023

Pathogenesis of Achromobacter xylosoxidans respiratory infections: colonization and persistence of airway epithelia and differential gene expression in synthetic cystic fibrosis sputum medium

Cystic fibrosis (CF) is a genetic disease affecting epithelial ion transport, resulting in thickened mucus and impaired mucociliary clearance. Persons with CF (pwCF) experience life- long respiratory mucosal infections caused by a diverse array of opportunists, and these infections are a leading cause of morbidity and mortality for pwCF. In recent years, there has been increased appreciation for the range and diversity of microbes in CF-related respiratory infections. Introduction of new therapeutics and improved detection methodology has revealed CF related opportunists such as Achromobacter xylosoxidans (Ax). Ax is a Gram-negative bacterial species that is widely distributed in the environment and has been increasingly observed in sputa and other samples from pwCF; typically Ax infections occur in patients in later stages of CF disease. In this study, we characterized CF clinical isolates of Ax and tested colonization and persistence of Ax in respiratory infection using immortalized human CF respiratory epithelial cells and BALB/c mice. Genomic analyses of clinical Ax isolates showed homologs for factors involved in flagellar synthesis, antibiotic resistance, and toxin secretion systems. Ax isolates adhered to polarized CFBE14o- human immortalized CF bronchial epithelial cells and caused significant cytotoxicity and depolarization. Ax colonized and persisted in mouse lung for up to 72 hours post infection, with inflammatory consequences that include increased neutrophilia, lung damage, cytokine production, and mortality. Transcript profiling reveled differential expression of Ax genes during growth in SCFM2 synthetic CF sputum media. Based on these results, we conclude that Ax is an opportunistic pathogen of significance in CF.

microbiology↗

bioRxiv2022

Pseudomonas aeruginosa promotes persistence of Stenotrophomonas maltophilia via increased adherence to depolarized respiratory epithelium

Stenotrophomonas maltophilia is an emerging opportunistic respiratory pathogen in patients with cystic fibrosis (CF). S. maltophilia is frequently observed in polymicrobial infections, and we have previously shown that Pseudomonas aeruginosa promotes colonization and persistence of S. maltophilia in mouse respiratory infections. In this study, we used host and bacterial RNA sequencing to further define this interaction. To evaluate S. maltophilia transcript profiles we used a recently described method for selective capture of bacterial mRNA transcripts with strain specific RNA probes. We found that factors associated with the type IV pilus, including the histidine kinase subunit of a chemotactic two-component signaling system (chpA), had increased transcript levels during polymicrobial infection. Using immortalized CF respiratory epithelial cells, we found that infection with P. aeruginosa increases adherence of S. maltophilia, at least in part due to disruption of epithelial tight junctions. In contrast, an isogenic S. maltophilia chpA mutant lacked cooperative adherence to CF epithelia and decreased bacterial burden in vivo in polymicrobial infections with P. aeruginosa. Similarly, P. aeruginosa lacking elastase (lasB) did not promote S. maltophilia adherence or bacterial colonization and persistence in vivo. Based on these results, we conclude that disruption of lung tissue integrity by P. aeruginosa promotes adherence of S. maltophilia to the lung epithelia in a type IV pilus-dependent manner. These data provide insight into S. maltophilia colonization and persistence in patients in later stages of CF disease and may have implications for interactions with other bacterial opportunists. IMPORTANCEDespite advances in treatment options for patients with cystic fibrosis (CF), complications of bacterial infections remain the greatest driver of morbidity and mortality in this patient population. These infections often involve more than one bacterial pathogen, and our understanding of how inter-species interactions impact disease progression is lacking. Previous work in our lab found that two CF pathogens, Stenotrophomonas maltophilia and Pseudomonas aeruginosa can cooperatively infect the lung to cause more severe infection. In the present study, we found that infection with P. aeruginosa promotes persistence of S. maltophilia by interfering with epithelial barrier integrity. Depolarization of the epithelial cell layer by P. aeruginosa secreted elastase increased S. maltophilia adherence, likely in a type IV pilus-dependent manner. Ultimately, this work sheds light on the molecular mechanisms governing an important polymicrobial interaction seen in pulmonary diseases such as CF.

microbiology↗