Antibiotic resistances have natural origins like antibiotics themself: the attempt to combat competing organisms with antimicrobials kills most of them (hmm, scientific attitude!) , except for the strongest, eg most resistant enemies. The selective pressure leads to an equilibrium between antimicrobials and resistances, but antibiotic pollution is pushing the balance strongly towards resistances.

Resistances are therefore rather wide spread and usually not restricted to the producing organism. Resistances are developing rapidly and - worse - can be transferred from organism to organism (see above).