Concomitant use of 2 or more antimicrobials for empiric or directed therapy

The use of 2 or more antimicrobials concomitantly for empiric therapy may be required to broaden the spectrum of activity (eg for empiric therapy of Staphylococcus aureus bacteraemia). If appropriate, therapy should be rationalised to single-drug directed therapy based on microbiology results and clinical response. Inappropriate use of combination therapy contributes to antimicrobial resistance and may result in harm to the patient.

Infrequently, 2 or more antimicrobials may be used concomitantly for directed therapy – seek expert advice. Synergistic therapy also requires the use of 2 or more antimicrobials.

If combination therapy is required, ensure that the benefit of combination therapy outweighs the increased risk of toxicity. Consider the risk of drug interactions between the antimicrobials.