Although alternative dosing strategies can improve antimicrobial exposure in critically ill patients, the high PK variability in this population means that some may still receive sub-optimal antibiotic exposure leading to unfavourable clinical outcomes.

Therapeutic drug management (TDM) guided dosing is the only safe and effective way to ensure that all critically ill patients achieve therapeutic antimicrobial exposures and to minimise the likelihood of toxicity.

For experts, TDM should be a standard of care, in particular for β-lactams. Nevertheless, because of the assay method for β-lactams and the need for bioanalytical experts, delays in obtaining results frequently occurred. These barriers, combined with difficulties in the interpretation of TDM results, need to be addressed in order to increase its routine utilization. Consequently, study aiming at identify which subgroup of patients or infection are more likely to benefit from TDM are urgently warranted This prospective observational study aimed at evaluating target attainment of piperacillin/tazobactam (PIP/TAZ) and cefepim (CEF) with the use of a Therapeutic Drug Monitoring (TDM) in critically patients during the routine care

Inclusion Criteria:

• Minimun age limits 18 years
• Critically ill patient receiving piperacillin or cefepim administered continuously

Exclusion Criteria:

• Beta lactam allergy
• Pregnancy
• Age less than 18 years

Critically ill patients admitted to the surgical intensive care unit whatever the reason of admission and who received piperacilin or cefepim with a TDM for sepsis or septic shock during their stay.