The majority of cases of sepsis are due to bacterial infections, some are due to fungal infections, and very few are due to other causes of infection or agents that may cause SIRS. The infectious agents, usually bacteria, begin infecting almost any organ location or implanted device (for example, skin, lung, gastrointestinal tract, surgical site, intravenous catheter, etc.). The infecting agents or their toxins (or both) then spread directly or indirectly into the bloodstream. This allows them to spread to almost any other organ system. SIRS criteria result as the body tries to counteract the damage done by these blood-borne agents.

Common bacterial causes of sepsis are gram-negative bacilli (for example, E. coli, P. aeruginosa, E. corrodens, and Haemophilus influenzae in neonates). Other bacteria also causing sepsis are S. aureus, Streptococcus species, Enterococcus species and Neisseria; however, there are large numbers of bacterial genera that have been known to cause sepsis. Candida species are some of the most frequent fungi that cause sepsis. In general, a person with sepsis can be contagious, so precautions such as hand washing, sterile gloves, masks, and clothing coverage should be considered depending on the patient's infection source.

What are the risk factors for sepsis?

The following groups are at increased risk for sepsis: The very young and the elderly are at greatest risk People who are very ill due to an infectious agent People in an intensive-care unit People with weakened or compromised immune systems People with devices such as IV catheters, breathing tubes, or other devices People with extensive burns People with severe