Secondary pneumonia in critically ill ventilated patients with COVID-19 (preprint)

Background Pandemic COVID-19 caused by the coronavirus SARS-CoV-2 has a high incidence of patients with severe acute respiratory syndrome (SARS). Many of these patients require admission to an intensive care unit (ICU) for invasive artificial ventilation and are at significant risk of developing a secondary, ventilator-associated pneumonia (VAP). Objectives To study the incidence of VAP, as well as differences in secondary infections, and bacterial lung microbiome composition of ventilated COVID-19 and non-COVID-19 patients. Methods In this prospective observational study, we compared the incidence of VAP and secondary infections using a combination of a TaqMan multi-pathogen array and microbial culture. In addition, we determined the lung microbime composition using 16S RNA analyisis. The study involved eighteen COVID-19 and seven non-COVID-19 patients receiving invasive ventilation in three ICUs located in a single University teaching hospital between April 13th 2020 and May 7th 2020. Results We observed a higher percentage of confirmed VAP in COVID-19 patients. However, there was no statistical difference in the detected organisms or pulmonary microbiome when compared to non-COVID-19 patients. Conclusion COVID-19 makes people more susceptible to developing VAP, partly but not entirely due to the increased duration of ventilation. The pulmonary dysbiosis caused by COVID-19, and the array of secondary infections observed are similar to that seen in critically ill patients ventilated for other reasons.

Development and implementation of a customised rapid syndromic diagnostic test for severe pneumonia (preprint)

Background The diagnosis of infectious diseases has been hampered by reliance on microbial culture. Cultures take several days to return a result and organisms frequently fail to grow. In critically ill patients this leads to the use of empiric, broad-spectrum antimicrobials and mitigates against stewardship. Methods Single ICU observational cohort study with contemporaneous comparator group. We developed and implemented a TaqMan array card (TAC) covering 52 respiratory pathogens in ventilated patients undergoing bronchoscopic investigation for suspected pneumonia. The time to result was compared against conventional culture, and sensitivity compared to conventional microbiology and metagenomic sequencing. We observed the clinician decisions in response to array results, comparing antibiotic free days (AFD) between the study cohort and comparator group. Findings 95 patients were enrolled with 71 forming the comparator group. TAC returned results 61 hours (IQR 42-90) faster than culture. The test had an overall sensitivity of 93% (95% CI 88-97%) compared to a combined standard of conventional culture and metagenomic sequencing, with 100% sensitivity for most individual organisms. In 54% of cases the TAC results altered clinical management, with 62% of changes leading to de-escalation, 30% to an increase in spectrum, and investigations for alternative diagnoses in 9%. There was a significant difference in the distribution of AFDs with more AFDs in the TAC group (p=0.02). Interpretation Implementation of a customised syndromic diagnostic for pneumonia led to faster results, with high sensitivity and measurable impact on clinical decision making. Funding Addenbrookes Charitable Trust, Wellcome Trust and Cambridge NIHR BRC

A blueprint for the implementation of a validated approach for the detection of SARS-Cov2 in clinical samples in academic facilities (preprint)

The COVID-19 pandemic is expanding at an unprecedented rate. As a result, diagnostic services are stretched to their limit, and there is a clear need for the provision of additional diagnostic capacity. Academic laboratories, many of which are closed due to governmental lockdowns, may be in a position to support local screening capacity by adapting their current laboratory practices. Here, we describe the process of developing a SARS-Cov2 diagnostic workflow in a conventional academic Containment Level 2 (CL2) laboratory. Our outline includes simple SARS-Cov2 deactivation upon contact, the methods for a quantitative real-time reverse transcriptase PCR (qRT-PCR) detecting SARS-Cov2, a description of process establishment and validation, and some considerations for establishing a similar workflow elsewhere. This was achieved under challenging circumstances through the collaborative efforts of scientists, clinical staff, and diagnostic staff to mitigate to the ongoing crisis. Within 14 days, we created a validated COVID-19 diagnostics service for healthcare workers in our local hospital. The described methods are not exhaustive, but we hope may offer support to other academic groups aiming to set up something comparable in a short time frame.