We seek to characterise the burden and outcomes of and understand the current experience of people who inject drugs admitted to hospital with invasive injecting-related infections, in order to implement and evaluate strategies to improve completion of therapy and reduce patient-directed discharges, with ultimate benefit to the patient and health service.

This study will be conducted as a prospective, observational cohort study of adults admitted with invasive bacterial and fungal infectious diseases. This study will be conducted at multiple hospitals in Australia.

Participants will be invited for Screening whilst they are inpatients of the hospital. Participants will be screened for history of injection drug use in the last 6 months and presence of an invasive bacterial or fungal infection.

Eligible participants will be treated through standard of care with the applicable treatment. All participants will commence antimicrobial treatment whilst they are inpatients. For participants who are discharged before planned treatment completion, a hospital discharge visit (Early Discharge Electronic Case Report Form [eCRF]) will be conducted. Following the end of treatment, participants will be reviewed at 6, 12 and 48-weeks post-enrolment. At follow-up visits, behavioural surveys, health-related quality of life, and experiences with hospital care will be assessed.

Individual patient involvement will include four visits over a 12-month period.

The duration of the study is anticipated to be 5 years.

Inclusion Criteria:

1. Have voluntarily signed the informed consent form,
2. 18 years of age or older,
3. Injected drugs within the last 6 months,
4. Admitted to hospital with invasive bacterial or fungal infection, a. Examples of invasive infection include: bloodstream infection, bone and joint infection (osteomyelitis, septic arthritis, discitis), central nervous system infection (epidural abscess, meningitis), deep abscess (i.e., brain, liver, muscle, spleen), endovascular infection (infective endocarditis, septic thrombophlebitis, mycotic aneurysm, septic embolism), skin or soft tissue infection (necrotising fasciitis, myositis),

Exclusion Criteria:

1) Is unable or unwilling to provide informed consent or abide by the requirements of the study.

This study will be conducted as a prospective, observational cohort study of adults admitted with invasive bacterial and fungal infectious diseases. This study will be conducted at multiple hospitals in Australia.