One interesting piece of this puzzle is that one of the body's own antibiotics (well, technically it's an anti-microbial peptide) is cathelicidin [1], and it is regulated by vitamin D. Anywhere from 1/3 to 2/3 of Americans are deficient in vitamin D, depending on what cutoff you use to determine deficiency.<p>In other words, doctors may want to ease up on prescribing antibiotics until they have checked a patient's vitamin D and taken care of that problem. Some of the infections will likely go away after the body has enough fuel to fight back.<p>[1] <a href="http://en.wikipedia.org/wiki/Cathelicidin" rel="nofollow">http://en.wikipedia.org/wiki/Cathelicidin</a>