A danger associated with fighting bacteria with antibiotics is bacterial resistance to the drug. Bacterial resistance occurs when bacteria with a mutation that provides resistance to an antibiotic is present. The drug will effectively wipe out non-resistant bacteria but the ones that are resistant will be left alive and capable of transmitting this resistant gene to offspring after asexual reproduction. Bacteria are also capable of conjugation. During this process, two different bacteria can exchange parts of their D.N.A. and resistance genes can be transmitted to bacteria that are not resistant in this way. Antibiotics that were once very effective in fighting different infections are no longer useful. In a way, selection is occurring and the selecting agent is the antibiotic which kills off the weaker germs leaving behind the resistant ones. Another danger is a constant search for newer and stronger antibiotics.