Managing infective endocarditis in people who inject drugs
The principles of managing infective endocarditis in people who inject drugs are the same as for any other patient. However, prolonged intravenous antibiotic therapy may be challenging or not feasible due to the epidemiological, social and drug-dependency characteristics of this population. As for any other patient, people who inject drugs should be assessed for their suitability to receive ambulatory antimicrobial therapy for infective endocarditis.
To improve patient engagement with their care, involvement of additional specialities including addiction medicine (especially if the patient is opiate or amfetamine addicted), pain management and psychiatry may be required, depending on the individual case.
Current injecting drug use or injecting drug use in the past 6 months is a risk factor for infection with methicillin-resistant Staphylococcus aureus (MRSA); see Risk factors for infection with methicillin-resistant Staphylococcus aureus to assess the risk of infection with MRSA and the implications of this for empirical therapy of infective endocarditis.
The type of drug the person uses, the route of use (eg intravenous, inhalational) and the sterility of use can also impact on the likely pathogen involved in infective endocarditis. For factors impacting the likely pathogens in people who inject drugs, see Factors impacting likely pathogens involved in skin and soft tissue infections and bacterial endocarditis in people who inject drugs. People who inject drugs may also smoke drugs. Using a bong (water pipe) can be associated with faecal gram-negative or anaerobic lung abscess or bacteraemia (and therefore possibly bacterial endocarditis), if the water in the bong is not changed regularly and becomes contaminated from the cannabis plant.
Treatment options can be complex for people who inject drugs who cannot be treated with the standard regimens for infective endocarditis. For alternative options for the treatment of staphylococcal endocarditis in people who inject drugs, see Native and prosthetic valve endocarditis caused by staphylococci in people who inject drugs. For alternative options for the treatment of other causes of infective endocarditis in people who inject drugs, seek expert advice.
- Nonsterile injecting may result in local injection-site skin and soft tissue infections, as well as extensive septic vein thrombosis (septic thrombophlebitis). Septic vein thrombosis poses a risk of bacteraemia and bacterial endocarditis, and may require prolonged therapy.
- Skin pathogens (eg Staphylococcus aureus – both methicillin-susceptible and methicillin-resistant strains) are a common cause of infective endocarditis, particularly if sterile injecting technique is not used.
- Infection with oral flora (eg viridans streptococci) is more likely if the person uses saliva to clean the injecting site or licks the injection needles.
- Infection with water-borne or faecal pathogens (eg Escherichia coli, Pseudomonas species) may be associated with use of drugs that are dissolved in water (eg ‘white’ heroin, amfetamines, metamfetamine [methamphetamine or ‘ice’]), depending on the source and sterility of the water.
- Use of ‘brown’ heroin (manufactured from oral opiate analogues such as codeine), which usually needs to be dissolved in lemon juice, is associated with an increased risk of fungal contamination (especially Candida species) and subsequent fungal endocarditis.