Of the 200 enrolled in this study, 25 patients were excluded from the analysis of the data. Of these, 21 patients had incomplete sampling and four patients met exclusion criteria. The characteristics on admission of the 175 patients included in our analysis study group are presented in Table 1 . Mean age was 62 years; roughly one-third had CAP, one-third had HAP, and one-third had VAP. The median hospital and ICU lengths of stay prior to enrolment were six days (range 0 to 368 days) and nine days (range 0 to 42 days), respectively.