Biology subjects

Rapsinski, G. J.

Publications and source records attributed to Rapsinski, G. J..

3 recordsLinked to original sources

bioRxiv2025

Respiratory viral infection is associated with increased Pseudomonas abundance in cystic fibrosis airways

Acute respiratory viral infections are an important driver of morbidity and mortality in people with chronic lung disease and are frequently associated with pulmonary exacerbations and a transition from intermittent to chronic bacterial infection of the airways. Chronic Pseudomonas aeruginosa infections are associated with worsened lung function, poor outcomes, and increased hospital visits. We sought to improve understanding of the effects of respiratory viral infections and host immune response on the resident bacterial community of the airways, using cystic fibrosis as a model. We performed an observational longitudinal study of 38 adults with CF and collected sinus and sputum samples at 6-month intervals from 2017 - 2021. We performed 16S rRNA amplicon sequencing to characterize the airway microbiota, real-time RT-PCR for viral infection detection, and cytokine quantification. We observed viral positivity rates of 19% and 14% in sinus and sputum samples, respectively. Human rhinovirus was the most frequently observed viral pathogen in both sinus and sputum samples. We measured a significant perturbance of the bacterial community during viral infection that did not return to baseline following resolution of the viral infection. This perturbation was driven by a significant increase in Pseudomonas relative abundance during viral infection. Furthermore, we found significant associations with increased Pseudomonas relative abundance for several pro-inflammatory and antiviral cytokines, including interleukin (IL)-2, IL-8, and interferon (IFN)-{lambda}1. These findings indicate an important role for respiratory viral infections and the host immune response in the development and maintenance of chronic Pseudomonas infections in the context of CF airway disease and broadly expand our understanding of viral-bacterial coinfection of the airways. IMPORTANCERespiratory infections are a leading cause of morbidity and mortality worldwide, and co-infections are associated with worsened disease outcomes. In viral-bacterial co-infection, clinical and mechanistic studies show that a preceding acute respiratory viral infection promotes the establishment and exacerbation of bacterial infections, leading to increased morbidity. Although people with cystic fibrosis do not experience more frequent acute respiratory viral infections, their outcomes are worse, with prolonged symptoms and hospitalizations. When examining how acute viral infections shape the microbiota in the respiratory tract of pwCF, we observe a disturbance of the microbial community composition during viral infections that does not return to baseline after the acute viral infection resolves. Moreover, we show that Pseudomonas relative abundance is significantly increased in the airways of pwCF during viral infection and that increased concentrations of antiviral cytokines - such as interferon (IFN)-{lambda}1 - are associated with increased Pseudomonas abundance. These findings offer evidence that the progression of chronic Pseudomonas infections in pwCF are influenced by acute respiratory viral infections and the subsequent antiviral response in the airways. This study furthers our understanding of viral-bacterial coinfection in the context of CF.

microbiology↗

bioRxiv2024

Mutations Leading to Ceftolozane/Tazobactam and Imipenem/Cilastatin/Relebactam Resistance During in vivo exposure to Ceftazidime/Avibactam in Pseudomonas aeruginosa

Identifying resistance mechanisms to novel antimicrobials informs treatment and antimicrobial development, but frequently identifies multiple candidate resistance mutations without resolving the driver mutation. Using whole genome sequencing of longitudinal Pseudomonas aeruginosa that developed imipenem/cilastatin/relebactam and ceftolozane/tazobactam resistance during ceftazidime/avibactam treatment, we determined mutations resulting in cross-resistance. Penicillin-binding protein ftsI, transcriptional repressor bepR, and virulence regulator pvdS were found in resistant isolates. We conclude that peptidoglycan synthesis gene mutations can alter the efficacy of multiple antimicrobials.

microbiology↗

bioRxiv2023

Pseudomonas aeruginosa senses and responds to epithelial potassium flux via Kdp operon to promote biofilm biogenesis

Mucosa-associated biofilms are associated with many human disease states, but the mechanisms by which the host promotes biofilm biogenesis remain unclear. In chronic respiratory diseases like cystic fibrosis (CF), Pseudomonas aeruginosa establishes chronic infection through biofilm formation. P. aeruginosa can be attracted to interspecies biofilms through potassium currents emanating from the biofilms. We hypothesized that P. aeruginosa could, similarly, sense and respond to the potassium efflux from human airway epithelial cells (AECs) to promote biofilm biogenesis. Using respiratory epithelial co-culture biofilm imaging assays of P. aeruginosa grown in association with CF bronchial epithelial cells (CFBE41o-), we found that P. aeruginosa biofilm biogenesis was increased by potassium efflux from AECs, as examined by potentiating large conductance potassium channel, BKCa (NS19504) potassium efflux. This phenotype is driven by increased bacterial attachment and increased coalescence of bacteria into aggregates. Conversely, biofilm formation was reduced when AECs were treated with a BKCa blocker (paxilline). Using an agar-based macroscopic chemotaxis assay, we determined that P. aeruginosa chemotaxes toward potassium and screened transposon mutants to discover that disruption of the high-sensitivity potassium transporter, KdpFABC, and the two-component potassium sensing system, KdpDE, reduces P. aeruginosa potassium chemotaxis. In respiratory epithelial co-culture biofilm imaging assays, a KdpFABCDE deficient P. aeruginosa strain demonstrated reduced biofilm growth in association with AECs while maintaining biofilm formation on abiotic surfaces. Collectively, these data suggest that P. aeruginosa biofilm formation can be increased by attracting bacteria to the mucosal surface via a potassium gradient and enhancing coalescence of single bacteria into microcolonies through aberrant AEC potassium efflux sensed through the bacterial KdpFABCDE system. These findings suggest that electrochemical signaling from the host can amplify biofilm biogenesis, a novel host-pathogen interaction, and that potassium flux could be a potential target for therapeutic intervention to prevent chronic bacterial infections in diseases with mucosa-associated biofilms, like CF. Author SummaryBiofilm formation is important for Pseudomonas aeruginosa to cause chronic infections on epithelial surfaces during respiratory diseases, like cystic fibrosis (CF). The host factors that promote biofilm formation on host surfaces are not yet fully understood. Potassium signals from biofilms can attract P. aeruginosa, but it is unknown if potassium from the human cells can influence P. aeruginosa biofilm formation on a host surface. We found that P. aeruginosa biofilm formation on human airway cells can be increased by the potassium currents from airway cells, and determined bacterial genes related to potassium uptake and sensing that contribute to biofilm formation on airway cells. These findings suggest that P. aeruginosa can respond to host potassium signals by forming increased biofilm and that reducing chronic infections may be accomplished by reducing potassium coming from airway cells or blocking the bacterial proteins responsible for the biofilm enhancement by potassium currents.

microbiology↗