Background: With increasing frequency of resistant Gram-negative bacteria, temocillin has potential utility in reducing carbapenem use. The 2020 EUCAST guideline changes to temocillin breakpoints and reclassifies isolates with a minimum inhibitory concentration from 0.001-16mg/L as ‘susceptible, increased exposure’ necessitating 6g/day rather than the previous 4g/day, associated with significant cost implications.
Objectives: We explore the clinical utility and treatment failure rate of temocillin at 4g/day dosing.
Method: All adult inpatient electronic prescriptions of temocillin (3 days or greater) from March 2016 to October 2019 were retrieved using a clinical decision support system (ICNET®). Treatment success was defined as survival, no switch to broad-spectrum agent for the same indication, no subsequent recrudescence of infection, occurring within 30days.
Results: Temocillin was used in 205 eligible patient-episodes, median age 79years (IQR:71-87years), 42.4% female. Median temocillin course length 5.9days (IQR:4.6-7.8days). Indications for use: urinary tract infection (UTI) (n=141), pneumonia (n=53), other (n=11). 144 (70.2%) patients had targeted treatment; 74 (36.1%) against Escherichia coli, 70 (34.4%) other Enterobacterales. 130 (63%) patients received 4g/day; the remaining patients had reduced renal function with dosing in accordance with guidance. Overall temocillin treatment success was 79.5%; highest when used to treat UTI 85.8% (versus 67.9% in respiratory infections, p=0.008). Empirical treatment demonstrated 82.0% (50/61) success (versus 78.5% (113/144) among targeted treatment, p=0. 71).
Discussion: 4g/day temocillin is an effective and safe alternative in treating patients with Gram-negative infections, but should be considered in the context of patient age and co-morbidities. Increased dosing or alternate strategies may be indicated when the infection is not of a urinary source.