Clinical Success Rates Similar for Oral vs IV-Only Therapy in Infective Endocarditis

Treatment with oral vs intravenous (IV)-only antimicrobial therapy produces similar outcomes among patients with infective endocarditis (IE), though adverse events (AEs) are less likely with oral therapy. These study results were published in Clinical Infectious Diseases.

This multicenter, retrospective cohort study used data captured from adults hospitalized with IE in Los Angeles, California between December 2018 and June 2022. Researchers compared outcomes among adult patients with definite and confirmed IE who received either oral or IV-only antimicrobial therapy. The primary efficacy endpoint was clinical success at 90 days, defined as survival without bacteremia recurrence or treatment-emergent infectious complications. Secondary outcomes included clinical success at the last follow-up visit, treatment-related AEs, length of hospitalization, and hospital readmission. Multivariable logistic regression was used to assess outcomes of clinical success at 90 days.

The final analysis included 46 patients in the oral therapy group and 211 in the IV-only therapy group, of whom the median ages were 39 (IQR, 30.5-61.8) and 55 (IQR, 42-65) years, 30.4% and 28.0% were women, and 37.0% and 18.0% reported injection drug use, respectively. For patients in the oral therapy group, the most commonly prescribed medication was oral linezolid (65.2%; 600 mg twice daily), with (86.7%) or without (13.0%) rifampin.

Among patients in the oral and IV-only therapy groups, Staphylococcus aureus was the most commonly isolated pathogen (52.1% vs 63.0%, respectively). Of patients with S aureus, methicillin-resistant S aureus (MRSA) was the causative pathogen for IE among 34.8% of those in the oral therapy group and 20.4% of those in the IV-only therapy group. In addition, streptococcal organisms were noted among 21.7% and 28.4% of patients in the oral and IV-only therapy groups, respectively.

There were no significant between-group differences observed for bacteremia recurrence, treatment-emergent complications, mortality, and 90-day readmission rates. Clinical success at 90 days was also similar between the groups, noted among 87% of patients in the oral therapy group and 84.4% of those in the IV-only therapy group (P =.66). At the last follow-up visit, clinical success was achieved by 76.1% and 82.0% of patients who received oral vs IV-only therapy, respectively (P =.36).

Adverse events were reported by significantly more patients in the IV-only vs oral therapy groups (27.5% vs 8.7%; P =.004), with similar findings observed after adjustment for comorbidities. Of note, acute kidney infection occurred among significantly more patients who received IV-only vs oral therapy (10.9% vs 2.2%; P =.048).

Limitations of this study include its retrospective design and potentially insufficient follow-up data.

According to the researchers, “[I]t is possible to select patients with IE based on rational clinical criteria that can be safely treated with oral therapy, including patients infected with MRSA.”