Temocillin use in England: clinical and microbiological efficacies in infections caused by extended-spectrum and/or derepressed AmpC β-lactamase-producing Enterobacteriaceae

BACKGROUND: Temocillin, a β-lactam stable against most β-lactamases including extended-spectrum β-lactamases (ESBLs) and derepressed AmpC cephalosporinases (dAmpC), has been suggested as an alternative to carbapenems when Pseudomonas can be excluded. Aims To assess temocillin clinical and microbiological cure rates (CCR and MCR) in infection caused by ESBL/dAmpC-producing Enterobacteriaceae and the effects of different dosage regimens. METHODS: Data were collected retrospectively from patients treated for at least 3 days with temocillin for urinary tract infection (n = 42), bloodstream infection (n = 42) or hospital-acquired pneumonia (n = 8) in six centres in the UK. RESULTS: Data on 92 infection episodes were collected. Overall CCR and MCR were 86% and 84% respectively; ESBL/dAmpC status had no effect. Significantly higher CCR and MCR occurred in patients treated with temocillin at optimal dosage 2 g twice daily or renally adjusted equivalent (ORAE) compared with those treated with a suboptimal dosage (<2 g twice daily ORAE) (CCR 91% and MCR 92% versus CCR 73% and MCR 63%). This difference was more pronounced in the ESBL/dAmpC-positive subset (CCR 97% and MCR 97% versus CCR 67% and MCR 50%). CONCLUSIONS: Clinical and microbiological efficacies of temocillin are unaffected by ESBL/dAmpC production, confirming its potential application as a carbapenem-sparing agent. Both CCR and MCR are optimized by a regimen of 2 g twice daily ORAE in ESBL/dAmpC-positive infection.