 The main purpose of the study is to examine gene expression response to infections. As a result, careful attention must be paid to how infections are classified. First, two systemic inflammatory reaction syndrome SIRS criteria are NOT necessary to be designated as infected. Second, the time of diagnosis of infection and the time of extra blood sampling will be the time of clinical diagnosis, not the later time that cultures turn positive. It will thus be based on clinical judgement. Finally, post-hoc criteria for infections are described elsewhere. Patients need to eventually meet these criteria to be counted as infected; this will be done in the analysis phase, not the clinical phase. 