What causes sepsis?
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 [pneumonia], gastrointestinal tract [bacterial penetration or ruptured intestine from trauma], 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. 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.