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.