Common organisms among people who inject drugs (PWID)
Comment: The 2023 Duke-ISCVID IE Criteria propose new microbiology diagnostics (enzyme immunoassay for Bartonella species, polymerase chain reaction, amplicon/metagenomic sequencing, in situ hybridization), imaging (positron emission computed tomography with 18F-fluorodeoxyglucose, cardiac computed tomography), and inclusion of intraoperative inspection as a new Major Clinical Criterion. Additionally, the list of "typical" microorganisms causing IE was expanded (e.g., it now includes E. faecalis and all strep spp except pneumoniae and pyogenes) and provides for pathogens to be considered as typical only in the presence of intracardiac prostheses (e.g., Corynebacterium striatum and jeikeium, C. acnes, Pseudomonas aeruginosa). The requirements for timing and separate venipunctures for blood cultures were removed. Last, additional predisposing conditions (transcatheter valve implants, endovascular cardiac implantable electronic devices, prior IE) were clarified.
Comment: Using data from a prospective study of 344 patients with E. faecalis bacteremia evaluated with echocardiography, the authors demonstrated that designating E. faecalis as a "typical" endocarditis pathogen, regardless of the place of acquisition or the portal of entry improved the sensitivity to correctly identify definite endocarditis from 70% (modified Duke criteria) to 96% (enterococcal adjusted Duke criteria).
Comment: A review of the literature focuses on oral step-down therapy for treating IE.
Comment: Current IE management guidelines by the American Heart Association
Comment: The 2023 criteria were compared to 2000 modified Duke and 2015 European Society of Cardiology (ESC) criteria among 1,194 patients treated for IE 2017-2022 (35% with PVE and 24% with a cardiac implanted electronic device). 2023 criteria had a 97.6% Se and 46% Sp. In patients without CIED, Se was 94.8% and Se was 53.8%.
Rating: Important
Comment: The 2023 criteria were compared to 2000 modified Duke and 2015 European Society of Cardiology (ESC) criteria among 2,132 patients at two Swiss hospitals treated for IE 2014-2022. 2023 criteria showed a higher sensitivity (84%) than previous versions (70%). However, the specificity of the new clinical criteria was lower (60%) compared to earlier versions (74%).
Rating: Important
Comment: Nicely done review of IE in PWID, which has complicating factors of addiction medicine and psychosocial factors. Reviewing the literature, ~41% undergo valve surgery with reinfection common if not in substance use therapy. However, there is little uniform approach as centers vary in conservative to more aggressive surgical therapy of endocarditis.
Comment: Updated review of the management of right-sided IE. Right-sided IE accounts for 5% to 10% of all IE cases. Compared with left-sided IE, it is more often associated with intravenous drug use, intracardiac devices, and central venous catheters.
Rating: Important
Comment: This study examined 13 studies, including 1593 patients, of which 341 were IDU-IE in the meta-analysis. IDU-IE patients more frequently had tricuspid valve infection, Staphylococcus infection, and heart failure before surgery. Meta-analysis revealed no statistically significant difference between the two groups in 30-day post-surgical mortality or in-hospital mortality.
Comment: In patients with endocarditis on the left side of the heart (including cases due to streptococcus, Enterococcus faecalis, Staphylococcus aureus, or coagulase-negative staphylococci) who were in stable condition, changing to oral antibiotic treatment was noninferior to continued intravenous antibiotic treatment.
Rating: Important
Comment: Persons who inject drugs have 16.3x more invasive MRSA infections than others. MRSA infections increased dramatically from 4.1% in 2011 to 9.2% in 2016. Infection types were frequently associated with nonsterile injection drug use causing invasive MRSA infections, including endocarditis, osteomyelitis, and skin and soft tissue infections.
Comment: One-year mortality for patients who injected drugs and had a second bout of endocarditis was 36.3%. Staphylococcus aureus was the most common offending pathogen but occurred less commonly than in the patient’s first bout of IE.
Comment: Infective endocarditis from intravenous drug use increased from 7% to 12% of hospitalizations between 2000 and 2013 in the US (much higher rates reported by single-center studies).
Rating: Important
Comment: A minimally invasive approach may hold some promise with further study in assisting infection control in patients with TV disease.
Comment: A study from Cleveland Clinic found a 10x risk of death or reoperation in the 3-6 month period after cardiac surgery in those who use injection drugs. Available follow-up after 6 mos shows a much smaller risk.
Comment: The authors review seven trials examining oral therapy for bacterial endocarditis. The most extensive study used ciprofloxacin and rifampin for right-sided disease, with equivalent results to traditional IV therapy (Heldman 1996), but it was still not sufficiently powered. Other smaller studies offer varying quality and outcomes.
Comment: In a review of 247 cases of endocarditis in San Francisco, 74% were injection drug users, most heroin users. OR for IDUs vs. others: S. aureus 5.5, E. faecalis 0.2. tricuspid valve 4.4, mitral valve 0.4.
Rating: Important
Comment: This is a retrospective study of patients with IE due to MSSA who received empiric vancomycin versus beta-lactam or beta-lactam + vanc. Vancomycin patients switched to beta-lactam therapy once susceptibility results became available and had outcomes inferior to those treated with beta-lactam from the initiation of therapy. Based on the observed results, empirical therapy with beta-lactam and an anti-methicillin-resistant S. aureus agent should be considered for serious S. aureus infections.
Rating: Important
Comment: A prospective trial of S. aureus endocarditis showed daptomycin (6mg/kg/day) was "not interior" to vancomycin therapy.
Rating: Important
Comment: A prospective study of 2,529 injection drug users x 10 yrs showed the incidence of endocarditis was 7/1000 pt yrs, which is about 100-fold higher than for non-ID users. Major pathogen - S. aureus in 76%, Strep 13% & Staph unspecified 7%.
Comment: The authors report a prospective study of cloxacillin vs. vancomycin x 14d for S. aureus endocarditis in injection drug users. All patients also received aminoglycosides. Cloxacillin proved superior to vancomycin, with cure rates of 100% & 60%, respectively.
Rating: Important
Comment: The authors conclude that no unifying hypothesis exists to explain this established association.
Comment: At the time, this was one of the few published prospective controlled trials of the treatment of endocarditis. The attempt was to find an adequate oral agent for IDU with S. aureus endocarditis. The authors showed cipro + rifampin x 4 weeks was as good as nafcillin + gent x 4 weeks; the side effects favored the oral regimen. The practical use of this oral regimen has been confounded by the increasing resistance of S. aureus to fluoroquinolones and the issue of reliability/compliance of this population to an oral regimen.
Comment: The authors review 144 cases of IE in injection drug users, including 45 with HIV S. aureus accounted for 65% of cases. Mortality was higher with a CD4 count < 200 (but this is from the pre-HAART era).
Comment: The authors present an alternative to tricuspid valve removal for refractory endocarditis in addicts. Vegetectomy with valvuloplasty is now frequently preferred.