Rifampicin as monotherapy for infections caused by Staphylococcus aureus: considerations for not applying 'breakpoints in brackets'.

EUCAST introduced 'breakpoints in brackets' to warn against the use of specified agents without additional therapeutic measures (EUCAST. Guidance document "EUCAST breakpoints in brackets". 2021. Available at: www.mic.eucast.org.). Rifampicin is rarely used as monotherapy for Staphylococcus aureus infections, yet its breakpoints remain unbracketed. Here, we explore whether this remains appropriate. Although frequent emergent resistance largely precludes rifampicin's use as monotherapy, this does not meet EUCAST's core criterion for bracketing-that an agent is inherently ineffective as monotherapy.