Oral and gut microbiome biomarkers of susceptibility to respiratory tract infection in adults: a longitudinal cohort feasibility study (preprint)

Background and aim Respiratory tract infections (RTIs) are common in the community. There is some evidence that microbial biomarkers can be used to identify individuals most susceptible to RTI acquisition. We investigated the feasibility of recruiting healthy adults to collect at-home self-reported socio-demographic data and biological samples, saliva (oral) and stool (gut) at three time points (TPs): baseline/start of the study (TP-A), during an RTI (TP-B) and end of study (TP-C). Methods Healthy adults were recruited from two urban Bristol GP practices. To identify respiratory pathogens in all saliva samples and RTI-S stool samples reverse transcriptase PCR (RT-PCR) was applied. We compared oral and gut samples from participants who developed RTI symptoms (RTI-S) and those who remained healthy (no-RTI) using 16S rRNA profiling microbiome analysis to identify the core microbiome, alpha and beta diversity, and biomarkers for susceptibility to RTIs from baseline samples (TP-A) when all participants were healthy. Results We recruited 56 participants but due to the UK COVID-19 pandemic disruption we did not receive samples from 16 participants leaving 19 RTI-S and 21 no-RTI participants with socio-demographic and microbiome data. RT-PCR revealed coagulase-negative Staphylococcus carriage was significantly higher in RTI-S participants compared to those who remained healthy and RTI symptoms may have been due to viral influenzae and bacterial co-infection with Haemophilus influenzae . Core microbiomes of no-RTI participants contained a greater number of taxa compared to RTI-S participants. Microbial biomarkers of RTI susceptibility in the oral cavity were an increased abundance of the pathobiont Streptococcus sobrinus and decreased probiotic bacterium Lactobacillus salivarius whereas in the gut there was an increased abundance of the genus Veillonella and decreased abundance of Coprobacillus . Conclusion In our feasibility study we found oral and gut microbial biomarkers for susceptibility to RTI acquisition. Strategies to identify those most vulnerable to RTI in the community could lead to novel interventions to decrease respiratory infection and associated health services burden.

Diagnostic accuracy of Loop mediated isothermal amplification coupled to Nanopore sequencing for the detection of SARS-CoV-2 infection at scale in symptomatic and asymptomatic populations (preprint)

IntroductionRapid, high throughput diagnostics are a valuable tool, allowing the detection of SARS-CoV-2 in populations, in order to identify and isolate people with asymptomatic and symptomatic infections. Reagent shortages and restricted access to high throughput testing solutions have limited the effectiveness of conventional assays such as reverse transcriptase quantitative PCR (RT-qPCR), particularly throughout the first months of the COVID-19 pandemic. We investigated the use of LamPORE, where loop mediated isothermal amplification (LAMP) is coupled to nanopore sequencing technology, for the detection of SARS-CoV-2 in symptomatic and asymptomatic populations. MethodsIn an asymptomatic prospective cohort, for three weeks in September 2020 health care workers across four sites (Birmingham, Southampton, Basingstoke and Manchester) self-swabbed with nasopharyngeal swabs weekly and supplied a saliva specimen daily. These samples were tested for SARS-CoV-2 RNA using the Oxford Nanopore LamPORE system and a reference RT-qPCR assay on extracted sample RNA. A second retrospective cohort of 848 patients with influenza like illness from March 2020 - June 2020, were similarly tested from nasopharyngeal swabs. ResultsIn the asymptomatic cohort a total of 1200 participants supplied 23,427 samples (3,966 swab, 19,461 saliva) over a three-week period. The incidence of SARS-CoV-2 detection using LamPORE was 0.95%. Diagnostic sensitivity and specificity of LamPORE was >99.5% in both swab and saliva asymptomatic samples when compared to the reference RT-qPCR test. In the retrospective symptomatic cohort, the incidence was 13.4% and the sensitivity and specificity were 100%. ConclusionsLamPORE is a highly accurate methodology for the detection of SARS-CoV-2 in both symptomatic and asymptomatic population settings and can be used as an alternative to RT-qPCR.