Minimal inhibitory concentrations (MIC) of cefazolin and its concentration in serum. Neither cefazolin sensitivity of the bacteria isolated from the saliva/bronchial secretions nor serum cefazolin levels were different between control and pneumonia patients. Bacteria were isolated from the saliva pre- and postoperatively. Bronchial secretion and serum were obtained post-operatively for bacterial culture and determination of cefazolin levels. (A): Distribution of isolated bacteria according to their MIC values. The antibiotic level of all the saliva and bronchial secretion samples fell below 0.5 mg/L; marked by the vertical dashed line. (B): Distribution of isolated bacteria according to percentage of patients with that particular species in each group. (C): Serum cefazolin levels are expressed as "box and whiskers: 10–90 percentile" and compared using the non-parametric Mann-Whitney test between control and pneumonia patients (n = 18 and 5, respectively).