Septic means “rotten; putrid,” hence “septic tank.” Sepsis means bacteria in the bloodstream (see Germs — Differences Among Them). Technically, “bacteremia” means bacteria in blood, sepsis means bacteremia with shock (low blood pressure). But when somebody has a high fever & looks sick, we just say “septic.”
Sepsis often originates from infection in a specific organ, like pneumonia or kidney infection. In the debilitated, it may come from an infected bedsore. Knowing the source helps us guess which antibiotics to start with, although oftentimes an ER will cover for a large range of bacteria.
Sepsis has a high mortality rate. One reason is because certain germs produce toxins which cause the shock. So even though we can kill the germs with antibiotics, we need to keep the patient alive until the toxins wear off.
We find the exact bacteria by a blood culture. However, if the patient happened to have taken even one dose of an antibiotic ahead of time, the tiny amount will get in the culture and ruin it (without doing the patient any good at all). That’s one good reason not to take unprescribed antibiotics.
Signs of sepsis are fever plus rapid respirations, fast heart beat, and low blood pressure. A blood test for lactate also helps (high is bad, normal good). Some patients can look “septic” without infection, due to overwhelming inappropriate response of the immune system due to trauma, poisons, pancreatitis, surgery, blood clots, & other. Still, we say “sepsis” & treat them as such while we’re trying to figure it out.
We especially worry about possible sepsis in patients with weak immune systems who develop fever, or very new onset of chills or generalized muscle aches. See Conditions That May Cause Immunodeficiency.