A severe microbe-induced systemic infection with usually, but not always, positive blood culture results Suspect septicaemia in all patients who are very unwell and manifest severe symptoms. Patient history gives clues about the probable causative agent: first symptoms of the disease, their duration, recent interventions, underlying general diseases, alcohol use, respiratory or urinary tract symptoms, immunosuppressive medication, splenectomy, wounds, bites, dental problems, travelling, etc. Check serum CRP without delay in patients who are not to be admitted to hospital immediately. Consider the possibility of streptococcal and staphylococcal sepsis in patients with a skin infection. Petechiae and extensive haematoma: meningococcus, pneumococcus or Capnocytophaga canimorsus (for example, following a dog bite ) Check for nuchal rigidity, and assess the level of consciousness, to diagnose meningitis in all suspected cases of severe infection.