Morbidity and mortality of Serratia marcescens bacteraemia during the substance use epidemic

Abstract

BackgroundSerratia marcescens (S. marcescens) is an Enterobacterales species present throughout the environment and causes a range of infections. Historically, S. marcescens has been associated with persons who inject drugs (PWID), but literature is scarce. This study aimed to compare treatment characteristics and clinical outcomes between PWID and non-PWID with Serratia marcescens bacteraemia. MethodsThis was a retrospective cohort study of patients hospitalised with S. marcescens bacteraemia from 1 January 2013 to 31 December 2019 at a tertiary medical centre. Patients were included if they were aged ≥ 18 years and had at least one positive blood culture for S. marcescens. ResultsOf the 67 patients who met inclusion criteria, 14 were identified as PWID (21%) and 53 were non-PWID (79%). Persons who inject drugs were younger (median age: PWID 32 years, non-PWID 67 years) and less likely to have renal disease (PWID 7%, non-PWID 34%). Persons who inject drugs had a higher incidence of infective endocarditis (IE) (PWID 48%, non-PWID 0%) and were more likely to receive combination antimicrobial therapy (PWID 29%, non-PWID 2%). All-cause mortality at 12 months was comparable between groups (PWID 21%, non-PWID 21%). ConclusionThis study demonstrates that long-term outcomes of PWID are comparable with non-PWID, despite PWID being a younger cohort with fewer comorbidities. Clinicians should have high suspicion of IE in PWID with S. marcescens bacteraemia.