Pharmacokinetic/pharmacodynamic parameters of teicoplanin for predicting clinical outcome of glycopeptide-susceptible Enterococcus faecium bacteraemia

Objectives The objective of this study was to determine the pharmacokinetic/pharmacodynamic parameters of teicoplanin associated with optimal outcomes in glycopeptide-susceptible Enterococcus faecium (GSEF) bacteraemia. Patients and methods We conducted a retrospective review of GSEF bacteraemia cases treated with teicoplanin between 1 April 2009 and 30 May 2023. Total area under the concentration–time curve over 24 h (AUC24) was calculated using a Bayesian approach. The free AUC24 (fAUC24) was estimated based on patient serum albumin levels. MICs were determined using the gradient diffusion method (Etest), and the fAUC24/MICEtest ratio was calculated. The primary outcome was treatment failure, defined as a composite of (i) 30-day all-cause mortality and (ii) microbiological failure, defined as persistent bacteraemia (a positive follow-up blood culture obtained >72 h after initiation of appropriate therapy). Classification and regression tree analysis (CART) was employed to identify the optimal teicoplanin fAUC24/MICEtest value associated with treatment failure. Results A total of 76 patients were included. Treatment failure occurred in 18 patients (23.7%). A CART-derived teicoplanin fAUC24/MICEtest ≥ 462 was significantly associated with reduced treatment failure (P = 0.002). Multivariable regression analysis revealed that achievement of an fAUC24/MICEtest ≥ 462 was an independent predictor significantly associated with reduced treatment failure (OR, 0.099; 95% CI, 0.005–0.562; P = 0.032). Conclusions An fAUC24/MICEtest ≥ 462 was associated with a reduction in treatment failure in GSEF bacteraemia. Further studies are necessary to establish optimal pharmacokinetic/pharmacodynamic targets for GSEF bacteraemia.