Fig. 2.

The rapidity of empiric therapy and the choice of specific agents are determined by the clinical scenario of the patient with suspected sepsis. Immediate therapy is given to those with a high likelihood of infection, and severe illness and or shock. If biomarkers like procalcitonin are not elevated, and the patient is not severely ill, immediate therapy is not necessary, and some patients may not even have infection. Specific agents are chosen with a consideration of the most common site of infection (lung > abdomen > catheter-associated infection > urinary tract infection). Each site has a group of likely pathogens, but these can vary, depending on patient-specific risk factors for resistance, and local ICU patterns of drug-resistant organisms. In sepsis, gram-negatives are more common than gram-positive, but some patients may also have fungal infection