Patients with CAP had higher APACHE II and SOFA scores at inclusion than patients with VAP. Such a difference was not observed between VAP and HAP patients. The incidence of cardiovascular co-morbid conditions on admission to the ICU was lower in patients with VAP than in the other groups (Table 1) . Positive cultures of the microbiological samples taken within 48 h were reported in 119 patients (67.4%). Gram-positive organisms were isolated in 75 patients (42.9%) and Gram-negative organisms in 63 patients (36.0%). The detected microorganisms are shown in Time course of PCT levels PCT levels were elevated at the time of enrolment in all groups (Table 3) . Initial PCT levels were higher in CAP than VAP patients. The maximum PCT levels were higher in patients with CAP than those with HAP or VAP. Maximum PCT occurred a median of one to two days after inclusion into the study. As shown in Figure  1 , PCT levels were persistently higher in patients with CAP than those with HAP during the first week following inclusion. There was no difference of initial PCT levels in culture positive and culture negative patients ( 