Clinical outcomes in OPAT patients treated with ceftriaxone 4 g and ceftazidime 6 g extended interval dosing regimens.

Background: New dosing regimens for ceftriaxone 4 g/24 hours and ceftazidime 3 g/12 hours are convenient for patients receiving OPAT. To date, these have not been clinically validated.

Aim: To assess the tolerability, toxicity and effectiveness of once daily ceftriaxone (4 g) and 12 hourly ceftazidime regimens (3 g twice a day) in the OPAT setting.

Patients and methods: From April 2018 until March 2023; demographic, clinical, microbiological and outcome data were collected on all adult patients discharged to a community-based OPAT team in East London.

Results: There were 487 OPAT episodes. Fifty-three (10.9%) patients received ceftriaxone 4 g once a day and 20 (4.1%) ceftazidime 3 g twice a day. In the ceftriaxone group, the commonest conditions treated were orthopaedic, neurosurgical or diabetic foot infections. OPAT was used to expedite the discharge of 45 (84.9%) patients, the remainder were admission avoidance episodes. The commonest isolate causing infection was MSSA 23 (43.4%). There were no tolerability or toxicity episodes recorded. All patients were cured and bed days saved were 1266.In the smaller twice-daily ceftazidime cohort, seven (35%) patients were treated for necrotizing otitis externa, six (30%) for bronchiectasis and six (30%) for urinary tract infections. The commonest cause of infection was P. aeruginosa, 18 (90%). One case of nephrotoxicity was recorded. All patients were cured and bed days saved were 896.

Conclusions: Regimens of ceftriaxone 4 g once a day and ceftazidime 3 g twice a day were well tolerated and highly effective. If widely adopted, these regimens will save OPAT and nursing time and enable more patients to be treated.