Prevalence and recurrence of bacteraemia in hospitalised people who inject drugs - a single Centre retrospective cohort study in Denmark.

Background: People who inject drugs (PWID) have increased risk of acquiring blood-transmitted chronic viral infections such as Hepatitis B (HBV), Hepatitis C (HCV) and Human Immunodeficiency Virus (HIV) as well as increased risk of acquiring bacterial infections. We aimed to identify and describe bacteraemic episodes, their recurrence rates, predictive and prognostic factors amongst hospitalised PWID.
Methods: In this retrospective cohort study, we included 257 hospitalised PWID during 2000-2006 with follow up at the Department of Infectious Diseases, Hvidovre Hospital, Denmark. Data collection included comorbidity (HBV-, HCV-, HIV-, and psychiatric comorbidities), social information (contact to an addiction treatment centre, homelessness), opioid substitution treatment (OST), treatment completion and microbiology findings. There was a 10-years follow-up regarding mortality.
Results: The study identified 257 patients classified as PWID. Of these, 58 (22.6%) had at least one episode of bacteraemia during their first hospital admission. Recurrence was found in 29 (50.0%) of the bacteraemia cases. Staphylococcus aureus was the dominant microorganism of both first and recurrent episodes with 24 (41.4%) and nine (31.4%) of cases, respectively. A psychiatric diagnose was significantly associated with a lower risk of bacteraemia in the multivariate analysis (OR: 0.29, [95%CI: 0.11-0.77], P = 0.01). Mortality was significantly higher in patients with bacteraemia (17.2% vs. 3.0%, P < 0.01, OR: 6.67 [95%CI: 2.33-20], P < 0.01).
Conclusions: In hospitalised PWID, bacteraemia was found in 22.6% and was associated with at higher mortality. The most common microorganism of bacteraemia was S. aureus. Psychiatric comorbidity was significantly associated with a lower risk of bacteraemia.