Only in part. The identification of the vector (rodents) had more to do with the defeat of the Plague in the middle ages. The causitive agent of plague (a bacteria known as Yersinia pestis) was not known then, nor was the Germ Theory of Disease. People didn't even think to be hygenic in the way we take for granted, simply because they didn't think it had anything to do with the spread of disease.

Now, in my previous post, I may have implied that antibiotics were used to "cure" the Plague which ravaged Europe in the middle ages. This is of course, not true. Antibiotics didn't come along until much later. My point was simply to demonstrate that prior to the invention and common use of antibiotics, people used to die of those infections. If Plague were to break out TODAY, it would be quickly knocked down before it had chance to spread and become a problem. In fact Y. pestis can still be found in the US today, especially in the Southwest.