There is a broad range of antibiotics on the market and they are used mainly for infections cause by bacteria, viruses, fungi, and protozoas.  Although; many antibiotics can be effective, they can also have side effects and interact with your much needed vitamins and minerals.

Vitamin and Supplement Interaction
  • Lactobacillus– Many antibiotics can disturb the good/ friendly bacteria of the colon, resulting in diarrhea. Diarrhea can cause dehydration and reduce proper absorption of most, if not all nutrients.
  • Vitamin K is important for healthy blood clotting, antibiotics interfere by killing friendly bacteria in the large intestine, which is where production of vitamin K happens.

However
If you must take pharmaceutical grade antibiotics…There has been studies that states 

Vitamin C increases the absorption of certain antibiotics like trimethoprim sulfamethoxazole ( bactrium, cotrim, septra, Uroplus, etc…) which also helps those with cystic  fibrosis. 

Saccharomyces Boulardii – which is a harmless type of yeast that prevents diarrhea can be helpful.

Natural
As we all know one of the best potent antibiotics you have is good old fashion GARLIC. 
For more Info on Lactobaccillus Acidophilus: http://kcgoff.blogspot.com/2010/10/acidophilus_13.html