Objective: To determine the affect of ESBL production among Klebsiella species and Escherichia coli on cefepime effectiveness.
Methods: This was a retrospective, case-controlled study comparing the clinical and microbiologic responses of patients receiving cefepime for ESBL producing Klebsiella species or E. coli from a non-urine source with matched controls receiving cefepime for non-ESBL strains. Cases with ESBLs were included if they received monotherapy and were clinically evaluable. Non-ESBL controls were matched in a 2:1 ratio based on age, infection site, intensive care unit (ICU) stay, pathogen species and date of hospitalization.
Results: Ten patients receiving cefepime for ESBLs were matched to 20 controls. Most patients received cefepime 1g q12h. Patients receiving cefepime for an ESBL infection were 9.7 (95% CI: 1.4-68.8) and 28.5 (95% CI: 2.6-306.6) times as likely to have an unsuccessful clinical and microbiological response compared with those with a non-ESBL infection. The presence of an ESBL did not have a statistically significant effect on all cause or infection-related mortality.
Conclusion: These data indicate that ESBL production among non-urinary Klebsiella species and E. coli negatively affected cefepime effectiveness. Further studies are required to evaluate if higher doses of cefepime may improve responses in ESBLs that are initially susceptible.