When someone gets an infection, the first thought is, "we need to kill off the bacteria." It's not usually, "let's put some more bacteria in there!" However, that just may be a viable alternative to antibiotics. Certain bacteria produce antimicrobial toxins called bacteriocins, and they can use it to kill their own kind, especially when conditions are cramped and food is scarce. It's every man for himself, so to survive, these bacteria shoot the bacteriocins at the closely related species nearby that is causing the infection. Bad bacteria dead; infection gone; human happy.
Another promising alternative therapy that may take center stage in the post-antibiotic world is the use of cationic or antimicrobial peptides. Peptides are like mini-proteins, and these antimicrobial ones have the ability to both break up bacterial clusters by disrupting communication between the organisms and to kill them off [sources: Borel; Izadpanah and Gallo]. The bonus is that they may also stimulate our own immune systems to fight harder to wipe out the infection.
Boosting our immune systems may be a key component of fighting infection in the future. In addition to using cationic peptides to coax our immune systems into action, researchers are starting to toy with using human antibodies to identify invading bacterial cells at an infection site, thereby signaling the immune system to enter and destroy. Clinical studies for this therapy have shown promising results [source: Fernbro].