False-Positive Rates in Pediatric SARS-CoV-2 Serology Testing

False-Positive Rates in Pediatric SARS-CoV-2 Serology Testin

Cystic fibrosis pathogens persist in the upper respiratory tract following initiation of elexacaftor/tezacaftor/ivacaftor therapy

ABSTRACT Elexacaftor/tezacaftor/ivacaftor (ETI) therapy has revolutionized the treatment of cystic fibrosis (CF) for most affected individuals but the effects of treatment on sinus microbiota are still unknown. Changes to the airway microbiota in CF are associated with disease state and alterations to the bacterial community after ETI initiation may require changes to clinical management regimens. We collected sinus swab samples from the middle meatus in an observational study of 38 adults with CF and chronic rhinosinusitis (CRS) from 2017 to 2021 and captured the initiation of ETI therapy. We performed 16S and custom amplicon sequencing to characterize the sinus microbiota pre- and post-ETI. Real-time quantitative PCR (RT-qPCR) was performed to estimate total bacterial abundance. Sinus samples from people with CF (pwCF) clustered into three community types, dependent on the dominant bacterial organism: a Pseudomonas-dominant, Staphylococcus-dominant, and mixed dominance cluster. Shannon’s diversity index was low and not significantly altered post-ETI. Total bacterial load was not significantly lowered post-ETI. Pseudomonas spp. abundance was significantly reduced post-ETI, but eradication was not observed. Staphylococcus spp. became the dominant organism in most individuals post-ETI and we showed the presence of methicillin-resistant Staphylococcus aureus (MRSA) in the sinus both pre- and post-ETI. We also demonstrated that the sinus microbiome is predictive of the presence of Pseudomonas spp., Staphylococcus spp., and Serratia spp. in the sputum. Pseudomonas spp. and Staphylococcus spp., including MRSA, persist in the sinuses of pwCF after ETI therapy, indicating that these pathogens will continue to be important in CF airway disease management in the era of highly effective modulator therapies (HEMT).IMPORTANCEHighly effective modulator therapies (HEMT), such as elexacaftor/tezacaftor/ivacaftor (ETI), for cystic fibrosis (CF) have revolutionized patient care and quality of life for most affected individuals. The effects of these therapies on the microbiota of the airways are still unclear, though work has already been published on changes to microbiota in the sputum. Our study presents evidence for reduced relative abundance of Pseudomonas spp. in the sinuses following ETI therapy. We also show that Staphylococcus spp. becomes the dominant organism in the sinus communities of most individuals in this cohort after ETI therapy. We identified methicillin-resistant Staphylococcus aureus (MRSA) in the sinus microbiota both pre- and post-therapy. These findings demonstrate that pathogen monitoring and treatment will remain a vital part of airway disease management for people with cystic fibrosis (pwCF) in the era of HEMT

STAT2 dependent Type I Interferon response promotes dysbiosis and luminal expansion of the enteric pathogen Salmonella Typhimurium.

The mechanisms by which the gut luminal environment is disturbed by the immune system to foster pathogenic bacterial growth and survival remain incompletely understood. Here, we show that STAT2 dependent type I IFN signaling contributes to the inflammatory environment by disrupting hypoxia enabling the pathogenic S. Typhimurium to outgrow the microbiota. Stat2-/- mice infected with S. Typhimurium exhibited impaired type I IFN induced transcriptional responses in cecal tissue and reduced bacterial burden in the intestinal lumen compared to infected wild-type mice. Although inflammatory pathology was similar between wild-type and Stat2-/- mice, we observed decreased hypoxia in the gut tissue of Stat2-/- mice. Neutrophil numbers were similar in wild-type and Stat2-/- mice, yet Stat2-/- mice showed reduced levels of myeloperoxidase activity. In vitro, the neutrophils from Stat2-/- mice produced lower levels of superoxide anion upon stimulation with the bacterial ligand N-formylmethionyl-leucyl-phenylalanine (fMLP) in the presence of IFNα compared to neutrophils from wild-type mice, indicating that the neutrophils were less functional in Stat2-/- mice. Cytochrome bd-II oxidase-mediated respiration enhances S. Typhimurium fitness in wild-type mice, while in Stat2-/- deficiency, this respiratory pathway did not provide a fitness advantage. Furthermore, luminal expansion of S. Typhimurium in wild-type mice was blunted in Stat2-/- mice. Compared to wild-type mice which exhibited a significant perturbation in Bacteroidetes abundance, Stat2-/- mice exhibited significantly less perturbation and higher levels of Bacteroidetes upon S. Typhimurium infection. Our results highlight STAT2 dependent type I IFN mediated inflammation in the gut as a novel mechanism promoting luminal expansion of S. Typhimurium

STAT2 dependent Type I Interferon response promotes dysbiosis and luminal expansion of the enteric pathogen Salmonella Typhimurium.

The mechanisms by which the gut luminal environment is disturbed by the immune system to foster pathogenic bacterial growth and survival remain incompletely understood. Here, we show that STAT2 dependent type I IFN signaling contributes to the inflammatory environment by disrupting hypoxia enabling the pathogenic S. Typhimurium to outgrow the microbiota. Stat2-/- mice infected with S. Typhimurium exhibited impaired type I IFN induced transcriptional responses in cecal tissue and reduced bacterial burden in the intestinal lumen compared to infected wild-type mice. Although inflammatory pathology was similar between wild-type and Stat2-/- mice, we observed decreased hypoxia in the gut tissue of Stat2-/- mice. Neutrophil numbers were similar in wild-type and Stat2-/- mice, yet Stat2-/- mice showed reduced levels of myeloperoxidase activity. In vitro, the neutrophils from Stat2-/- mice produced lower levels of superoxide anion upon stimulation with the bacterial ligand N-formylmethionyl-leucyl-phenylalanine (fMLP) in the presence of IFNα compared to neutrophils from wild-type mice, indicating that the neutrophils were less functional in Stat2-/- mice. Cytochrome bd-II oxidase-mediated respiration enhances S. Typhimurium fitness in wild-type mice, while in Stat2-/- deficiency, this respiratory pathway did not provide a fitness advantage. Furthermore, luminal expansion of S. Typhimurium in wild-type mice was blunted in Stat2-/- mice. Compared to wild-type mice which exhibited a significant perturbation in Bacteroidetes abundance, Stat2-/- mice exhibited significantly less perturbation and higher levels of Bacteroidetes upon S. Typhimurium infection. Our results highlight STAT2 dependent type I IFN mediated inflammation in the gut as a novel mechanism promoting luminal expansion of S. Typhimurium