Many people with European ancestry going back to the Black Death are immune to all types of plague (Yersinia pestis infections) as well as HIV. This is because coincidentally both the bacteria and the virus attack certain types of white blood cells that don't exist in many European descendants. Not all European descendants are immune and I don't think there are specific tests for you to find out.
Furthermore, I wouldn't count too much on antibiotics, as they are often overused in countries such as China, India, and even in the US. Various antibiotic resistant bacteria have already come out of antibiotic abuse and it's only a matter of time before many antibiotic drugs are no longer viable. The best protection against bacteria and viruses will always be good hygiene.