Severity

Clinical features

Mild

Patient systemically well

Moderate

Evidence of SIRSa

Severe

Patient has any of the following:

– Failed prior antibiotic therapy (± incision and drainage)

– Systemic signs of infection or hypotension

– Immunocompromise (eg, chemotherapy, organ transplant, neutropenia)

– Clinical signs of deeper infection (eg, necrotizing fasciitis)

a SIRS: Acute onset of ≥2 of:

1) Temperature >38.3°C or <36°C.

2) Heart rate >90 beats/min.

3) Respiratory rate >20 breaths/min or PaCO2 <32 mm Hg.

4) WBC count >12,000/microL or <4000/microL, or >10% of immature neutrophils in differential WBC count.