What do Koch's postulates help establish?

Koch's postulates are a set of criteria established by Robert Koch in the late 19th century, designed to demonstrate that a specific microorganism is the cause of a particular disease. These postulates outline a systematic approach to linking specific pathogens to specific diseases, which involves isolating the microbe from a diseased host, cultivating it in a pure culture, inoculating a healthy host to reproduce the disease, and then re-isolating the same microbe from this newly diseased host.

This framework laid the foundation for the field of microbiology and has been crucial in establishing causative links between microbes and various infectious diseases. While the other options address relevant areas in microbiology, they do not pertain directly to Koch's postulates. The infectious nature of pathogens, antibiotic resistance mechanisms, and the role of vaccines are all important topics, but they do not specifically relate to the direct establishment of a microbe's causal relationship to a disease as outlined by Koch.