Semmelweis's observations conflicted with the established scientific and medical opinions of the time and his ideas were rejected by the medical community. He couldn’t offer an acceptable scientific explanation for his findings even though he was able to show that midwives had a much better success rate. Some doctors were offended at the suggestion that they weren’t clean and should wash their hands. He was being ridiculed by many doctors and scientists. Keep in mind that the impact of bacteria/germs wasn’t common knowledge at the time.
In 1865, Semmelweis supposedly suffered a nervous breakdown and was committed to an insane asylum by one of his colleagues. In less than two weeks, and at the age of 47, he died from complications due to being beaten by guards.
Semmelweis's theories earned widespread acceptance years after his death, when Louis Pasteur confirmed the germ theory and the famous Sir Joseph Lister from Britain, began using hygienic methods during his surgeries, with great success. Not unlike some artists, Dr. Semmelweis didn’t become famous until after he died.