Model for PK/PD of Antimicrobials in Blood Stream Infection: Feasibility

Inclusion Criteria: * High probability of a blood stream infection; this is based on * the presence of SIRS \[Bone et al. 1992\] defined by more than one of the following clinical manifestations: 1. a body temperature greater than 38°C or less than 36°C 2. a heart rate greater than 90 beats per minute 3. tachypnea, manifested by a respiratory rate greater than 20 breaths per minute, or hyperventilation, as indicated by a PaCO2 of less than 32 mm Hg 4. an alteration in the white blood cell count, such as a count greater than 12,000/µl, a count less than 4,000/µl, or the presence of more than 10 percent immature neutrophils ("bands"). and * the assessment of the treating physician according to the patient's situation that the SIRS is caused by an infection (e.g., patients after treatment with cytotoxic drugs) * indication for antimicrobial treatment * Intended use of one of the following antimicrobial agents: piperacillin/tazobactam; vancomycin; meropenem; ampicillin/sulbactam; flucloxacillin; ceftriaxone; caspofungin (according to the decision of the project coordinator, use of other antimicrobial agents may also be included if anticipated to be used frequently) * Age: 18 years or older (no upper limit) * Willing and capable to provide written consent prior to enrolment after ample information has been provided Exclusion Criteria: * expected chances to successfully carry out venipunctures to obtain the blood samples required for the study are inadequately low according to the assessment of the physician * Anemia CTCAE grade \>2 (i.e., Hb \<8.0 g/dL / 4.9 mmol/L) * the clinical status of the patients suggests that the anticipated treatment of the patient or other conditions would make participation on the study inappropriate (e.g., terminally ill patients); the respective assessment is done by the treating physician