Interesting questions, which i will deal with using very simple terminology and with no links which will inevitably be produced by other contributors.
You are correct peptic ulcers were treated in the past by surgery...Gastrectomy, with varying results and quite a large recurrence rate. Later the identification of an organism (Helibacter pylori) was identified as a causative organism and treated successfully by non-surgical means (antibiotics)
Sepsis...a simple definition is the entering of an organism into the blood stream that overwhelms the immune response of the host eventually producing a shutdown of all the major organs...kidneys, liver, heart and lungs. The prognosis for this condition is poor.
Indeed it was known in the 50's as "blood poisoning", septicaemia, bacteraemia, but later became known as SEPSIS. Like many things in medicine, it has always been present, but the name has changed.
Is Sepsis on the increase? medical opinion states that it is butr the reason is not quite so obvious.The main reason is the use and abuse of antibiotics in such a way that organisms become resistant to them,but unfortunately many patients and even doctors do not see it that way. If one has an infection one doesn't necessarily need antibiotics and not finishing a course of antibiotics does not contribute to bacterial resistance in my opinion.
There you are, in a nutshell, luckily science is one step ahead of drug resistance, but.........for how long?