While working as a microbiology research assistant in the mid 70s there was a big stir around a microbiologist whose research showed that ulcers were caused by a specific bacterial infection. He was shouted down and told by the medical community to pound sand because ulcers were caused by stress. It only took about 25 years for his research to be accepted. A bacterial role in atherosclerosis would not be suprising.
The bacteria was/is H. Pylori.