Native and prosthetic valve endocarditis caused by staphylococci in people who inject drugs

Baddour, 2022

For principles of managing infective endocarditis in people who inject drugs, see Managing infective endocarditis in people who inject drugs.

For principles of antimicrobial therapy for infective endocarditis (including duration of therapy following valve surgery and considerations for ambulatory antimicrobial therapy), see Principles of antimicrobial therapy for infective endocarditis.

When possible, people who inject drugs who have staphylococcal endocarditis should receive the same therapy as other patients. For routine intravenous therapy, see:

However, for various reasons routine intravenous therapy for the required duration of treatment may not be possible or safe. Switching to oral antibiotics is superior to incomplete intravenous therapy and is associated with lower all-cause readmission ratesMarks, 2020. While routine intravenous therapy is preferred, if it is unlikely that the patient will complete intravenous therapy, switching from intravenous to oral antibiotics should be considered – seek expert advice.

If an alternative treatment regimen is considered, the patient should ideally have cleared their bacteraemia using routine intravenous therapy before switching.

For people who inject drugs who are suitable for intermittent outpatient intravenous therapy following routine intravenous therapy, the subsequent use of a long-acting intravenous lipoglycopeptide (eg dalbavancin, oritavancin) may be considered in some circumstances – seek expert adviceKussmann, 2018Tobudic, 2018Tobudic, 2019.

For people who inject drugs who are unsuitable for intravenous therapy, the choice of oral regimen will depend on:

  • the susceptibility of the staphylococcal isolate
  • the likely adherence to multidose therapy
  • potential drug interactions with methadone or other concurrent treatments.

Overall, clinical data for the efficacy of oral regimens are very limitedSpellberg, 2020. The most common regimen recommended is a combination of rifampicin plus a fluoroquinolone (eg ciprofloxacin, moxifloxacin)Dworkin, 1989Heldman, 1996. However, rifampicin can reduce the blood levels of methadone and dose adjustment may be required. The use of fluoroquinolones and methadone together may cause significant QT interval prolongation and torsades de pointes; obtain a baseline echocardiogram (ECG) and periodically monitor – seek expert advice. For comprehensive information on drug interactions, consult an appropriate drug information resource.