Clinical outcomes of temocillin use for invasive Enterobacterales infections: a single-centre retrospective analysis

BACKGROUND: With increasing frequency of resistant Gram-negative bacteria, temocillin has potential utility in reducing carbapenem use. The 2020 EUCAST guideline changes temocillin breakpoints and reclassifies isolates with an MIC of 0.001–16 mg/L as ‘susceptible, increased exposure’ necessitating 6 g/day rather than the previous 4 g/day, associated with significant cost implications. OBJECTIVES: We explore the clinical utility and treatment failure rate of temocillin at 4 g/day dosing. METHODS: 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 and no subsequent recrudescence of infection, occurring within 30 days. RESULTS: Temocillin was used in 205 eligible patient-episodes, median age 79 years (IQR : 71–87 years), 42.4% female. Median temocillin course length was 5.9 days (IQR : 4.6–7.8 days). Indications for use: urinary tract infection (UTI) (n = 141), pneumonia (n = 53), other (n = 11). In total, 144 (70.2%) patients had targeted treatment; 74 (36.1%) against Escherichia coli, 70 (34.4%) other Enterobacterales. A total of 130 (63%) patients received 4 g/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]. CONCLUSIONS: Temocillin at 4 g/day is an effective and safe alternative in treating patients with Gram-negative infections, but should be considered in the context of patient age and comorbidities. Increased dosing or alternate strategies may be indicated when the infection is not of a urinary source.