The trial, led by Danish researchers including Henning Bundgaard, tested a radical idea: rather than committing to a fixed duration of antibiotic therapy, clinicians would stop treatment once patients met predefined criteria for clinical stability. The results showed that this response-tailored strategy successfully shortened the overall treatment duration without increasing the risk of death or the need for cardiac surgery. However, the approach came with a notable trade-off: rates of relapse of endocarditis or bacteraemia were tripled compared with standard-duration therapy.

Infective endocarditis remains a formidable clinical challenge. The infection destroys valve tissue, can seed emboli throughout the body, and carries substantial mortality even with modern care. Standard guidelines, including the 2023 European Society of Cardiology recommendations, have long endorsed prolonged antibiotic courses — typically four weeks for many cases and six weeks for more complex infections — on the assumption that complete eradication of bacteria from vegetations requires sustained drug exposure.

The original POET trial, published in 2019, had already challenged one pillar of conventional treatment by showing that switching stable patients from intravenous to oral antibiotics partway through their course was non-inferior to continued intravenous therapy. That finding, later reinforced by the Danish POETry implementation study, reshaped practice in many centers and reduced the burden of prolonged central venous catheter use. POET II now pushes the logic one step further by questioning the total duration itself.

In the response-tailored arm of POET II, antibiotics were discontinued once patients achieved clinical stability — defined by criteria such as absence of fever, hemodynamic stability, and lack of ongoing bacteremia — rather than after a predetermined number of weeks. The trial’s rationale, outlined in its design publication, was that a subset of patients may clear their infection adequately with shorter exposure, and that continuing antibiotics in these individuals offers little added benefit while exposing them to catheter complications, adverse drug effects, and antimicrobial resistance pressures.

The tripling of relapse rates is the trial’s central caution. Relapse in endocarditis — distinguished from reinfection by the recurrence of the same microorganism, typically within weeks to months of treatment completion — signals that bacteria persisted within the vegetation despite therapy. In a commentary accompanying the trial, Mary Philip and Gilbert Habib of La Timone Hospital in Marseille emphasize that the safety of the response-guided strategy will depend fundamentally on rigorous patient selection and close multidisciplinary follow-up.

The distinction between relapse and reinfection carries practical weight. Relapse typically involves the same organism and suggests inadequate eradication, whereas reinfection involves a new episode with a different microorganism. The tripling observed in POET II suggests that, for some patients, stopping antibiotics at the point of clinical stability leaves residual bacteria capable of re-emerging. Identifying which patients harbor such residual infection — and which have truly cleared it — is the core challenge for tailored therapy.

Philip and Habib frame POET II as a genuine conceptual advance beyond the oral-switch paradigm of the original POET trial. Where POET changed the route of delivery without altering total exposure, POET II directly tests whether total exposure can be reduced. The commentary authors suggest that the era of one-size-fits-all duration may be giving way to individualized approaches, in which the intensity and length of therapy are calibrated to each patient’s clinical trajectory, microbiological profile, and response to initial treatment.

The implications for clinical practice are likely to be gradual rather than immediate. Guidelines will need to weigh the benefit of shorter treatment — fewer catheter days, lower drug toxicity, reduced selection pressure for resistance, and shorter hospital stays — against the increased relapse risk. Patient selection will be paramount: individuals with virulent organisms, large vegetations, prosthetic material, or complicated courses may remain poor candidates for early cessation, while stable patients with uncomplicated disease and sensitive organisms may benefit most.

Close follow-up will be equally critical. Patients treated with a response-tailored strategy will require vigilant monitoring for early signs of relapse, including recurrent fever, new bacteremia, or hemodynamic deterioration, with ready access to repeat imaging and blood cultures. Multidisciplinary teams — cardiologists, infectious disease specialists, cardiac surgeons, and microbiologists — will need coordinated protocols to detect and manage relapse promptly. As Philip and Habib conclude, POET II marks a genuine shift in thinking, but its safe adoption will depend on the discipline of its implementation: the right patients, the right criteria, and the right follow-up.

Subject of Research: Infective Endocarditis

Article Title: Duration of antibiotic treatment for infective endocarditis: should we move towards tailored therapy?

Article References: Philip, M., & Habib, G. (2026). Duration of antibiotic treatment for infective endocarditis: should we move towards tailored therapy?. Nature Reviews Cardiology. https://doi.org/10.1038/s41569-026-01360-1

Image Credits: AI Generated

DOI: 10.1038/s41569-026-01360-1

Keywords: infective endocarditis, antibiotics, POET II trial, tailored therapy, cardiology, infectious diseases, Duration, antibiotic, treatment, infective, endocarditis, should