Role of procalcitonin (PCT) in guiding antibiotic therapy Descriptive review of RCTs using PCT to guide antibiotic therapy –2 RCTs in outpatient primary care setting: About 1,000 patients with upper/lower respiratory tract infections Antibiotic use: PCT cut-off value of 0.25 µg/l was used –5 RCTs in emergency room and inpatient medical floor setting: Patients with COPD exacerbation, bronchitis and community-acquired pneumonia Antibiotic use: control group according to standard of care vs PCT group according to algorithm (start if PCT level >0.25 µg/l, stop if PCT level <0.25 µg/l) –Several RCTs in ICU setting: Antibiotic use: started in control and PCT group but stopped according to PCT-based algorithm Maskey M. IDSA 2012 abs of 2

Role of procalcitonin (PCT) in guiding antibiotic therapy Significant reduction in antibiotic use –In outpatient setting –In PCT-guided group compared with control group in emergency/inpatient setting Shorter duration of antibiotic treatment in ICU setting in PCT vs control group Similar clinical outcome in PCT group compared with control group No adverse clinical outcome in PCT group in either study PCT seems a promising biomarker for bacterial infection and may give guidance in antibiotic therapy Maskey M. IDSA 2012 abs of 2

Longitudinal analysis of leukocyte differentials in peripheral blood of patients with acute influenza infection Retrospective study of experimental human challenge tests with influenza A/Wisconsin/67/2005 (H3N2) to assess temporal development and time-dependent utility of leukocyte differential Of 17 inoculated volunteers, 9 (53%) developed symptomatic infection Peripheral blood: daily measurement of differentials from immediately prior to inoculation to resolution of disease McClain M. IDSA 2012 abs.93 1 of 2

Longitudinal analysis of leukocyte differentials in peripheral blood of patients with acute influenza infection Lymphocyte:monocyte ratio of <2 at the time of maximal symptoms correctly classified 100% of the volunteers according to symptom status Despite usefulness of leukocyte differentials to determine infected status, its utility is heavily time dependent McClain M. IDSA 2012 abs.93 2 of 2