Aim To implement recommendations for oral hygiene before elective open-heart surgery in a thoracic surgery ward and to evaluate whether the number of patients who needed to be treated with antibiotics postoperatively was reduced.

Background Healthcare systems are challenged to implement initiatives that reduce the development of nosocomial infections, to offer patients a safe and cost-efficient treatment and to reduce the use of antibiotics. Previous interventions have focused on staff behaviour in reducing postoperative infections. In this study, patients were recommended to carry out oral hygiene as recommended in a clinical guideline.

Methods A quasiexperimental design with a control and an intervention group was used. Information on adherence to the recommendation was collected at admission. All medical information and prescriptions of antibiotics were obtained from patients’ medical records. Data were reported as intention to treat.

Results Altogether 972 patients (506 controls and 466 interventions) were included in the study. Of the intervention patients, 405 (86.9%, 95% CI 83.3 to 89.8) reported that they had adhered to the oral hygiene recommendation. 64 (12.6%) control patients and 36 (7.7%) in the intervention group (p=0.015) were treated with antibiotics postoperatively.

Conclusions It was feasible to involve patients in a programme for oral hygiene and thereby reduce the number of patients needing antibiotics after open-heart surgery and this might contribute to reducing costs.