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Time to positivity in bloodstream infection is not a prognostic marker for mortality: analysis of a prospective multicentre randomized control trial

Hamilton, Fergus, Evans, Rebecca, Ghazal, Peter ORCID: and MacGowan, Alasdair 2022. Time to positivity in bloodstream infection is not a prognostic marker for mortality: analysis of a prospective multicentre randomized control trial. Clinical Microbiology and Infection 28 (1) , 136.E7-136.E13. 10.1016/j.cmi.2021.05.043

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Objectives Time to positivity (TTP), calculated automatically in modern blood culture systems, is considered a proxy for microbial load and has been suggested as a potential prognostic marker in bloodstream infections. In this large, multicentre, prospectively collected cohort, our primary analysis aimed to quantify the relationship between the TTP of monomicrobial blood cultures and mortality. Methods Data from a multicentre randomized controlled trial (RAPIDO) in bloodstream infection were analysed. Bloodstream infections were classified into 13 groups/subgroups. The relationship between mortality and TTP was assessed by logistic regression, adjusted for site, organism, and clinical variables, and linear regression was applied to examine the association between clinical variables and TTP. Robustness was assessed by sensitivity analysis. Results In total 4468 participants were included in the RAPIDO. After exclusions, 3462 were analysed, with the most common organisms being coagulase-negative staphylococci (1072 patients) and Escherichia coli (861 patients); 785 patients (22.7%) died within 28 days. We found no relationship between TTP and mortality for any groups except for streptococci (odds ratio (OR) with each hour 0.98, 95%CI 0.96–1.00) and Candida (OR 1.03, 95%CI 1.00–1.05). There was large variability between organisms and sites in TTP. Fever (geometric mean ratio (GMR) 0.95, 95%CI 0.92–0.99), age (GMR per 10 years 1.01, 95%CI 1.00–1.02), and neutrophilia were associated with TTP (GMR 1.03, 95%CI 1.02–1.04). Conclusions Time to positivity is not associated with mortality, except in the case of Candida spp. (longer times associated with worse outcomes) and possibly streptococci (shorter times associated with worse outcomes). There was a large variation between median times across centres, limiting external validity.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Medicine
Publisher: Wiley
ISSN: 1198-743X
Date of First Compliant Deposit: 17 February 2022
Date of Acceptance: 1 May 2021
Last Modified: 10 Nov 2022 17:56

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