In short, it's evolution. Bacteria develop resistance when exposed to antibiotics. They lose their effectiveness. This will give you a decent overview of antib

In short, it's evolution. Bacteria develop resistance when exposed to antibiotics. They lose their effectiveness. This will give you a decent overview of antibiotic resistance: http://www.who.int/mediacentre/factsheets/antibiotic-resistance/en/ http://www.who.int/mediacentre/factsheets/antibiotic-resista... If you like to watch documentaries, Frontline has a few on the topic, though each show is several years old now which is an eon to pathogens https://www.pbs.org/wgbh/frontline/film/hunting-the-nightmare-bacteria/ https://www.pbs.org/wgbh/frontline/film/hunting-the-nightmar... (on youtube https://www.youtube.com/watch?v=gE4VzFz9PPo https://www.youtube.com/watch?v=gE4VzFz9PPo ) https://www.pbs.org/wgbh/frontline/film/trouble-with-antibiotics/ https://www.pbs.org/wgbh/frontline/film/trouble-with-antibio...