Improving metronidazole prescription practices in surgical patients: a full cycle audit

Metronidazole is commonly prescribed for intra-abdominal infections. Oral metronidazole has high bioavailability (>95%) and intravenous metronidazole should be reserved for patients not suitable for oral preparations.

This full cycle audit evaluated the type of metronidazole preparation prescribed in adult emergency surgical patients requiring first-line empirical antimicrobial therapy for intra-abdominal infections. The criterion for audit was the proportion of patients who were prescribed intravenous metronidazole when the oral route was available. The first cycle included all consecutive eligible patients between 20 April and 14 May 2020. After an intervention phase educating prescribers about the similar pharmacokinetic properties of oral and intravenous metronidazole, clinical practice was reaudited between 22 June and 16 July 2020. Data were collected by case note and drug chart review.

A total of 54 patients were included in the first audit cycle. Of these, 11 (20.4%) were prescribed oral metronidazole and 43 (79.6%) were prescribed intravenous metronidazole. In the majority of cases (35/43, 81.4%), intravenous metronidazole was prescribed in the absence of clear contraindications to the oral preparation. Of the 61 patients included in the reaudit cycle, 23 (37.7%) were prescribed oral metronidazole and 38 (62.3%) were prescribed intravenous metronidazole. The proportion of patients prescribed intravenous metronidazole despite being suitable for oral preparation decreased from 81.4% in the first cycle to 34.2% (13/38) in the reaudit cycle (risk ratio 0.42, 95% CI: 0.26 to 0.67, p<0.0001). Prescribing oral metronidazole when suitable saved up to £10.53/day per patient.

This full cycle audit led to a significant improvement in the use of oral metronidazole in suitable patients, as well as a considerable reduction in healthcare costs.