When an antibiotic attacks a particular bacterial infection there is always the chance that, within a population of bacteria, there will be some members with resistance. Those not killed are now free to multiply without any competition from the sensitive strains. Antibiotics can also wipe out friendly bacteria, which would otherwise compete with the resistant strain for resources. And to make matters worse, antibiotics can also increase resistance emerging in harmless bacteria which can, under certain conditions such as in an immune suppressed patient, become aggressive and cause infection. Just the existence of antibiotic resistant bacteria, harmful or not, increases the likelihood of resistance being passed on to other bacteria.
Resistance is a natural phenomenon perhaps as old as bacterium themselves.
However, we have contributed to an increase in the rate of antibiotic resistance through the increased transmission of infection and the misuse and abuse of antibiotics. Australia is one of the highest users of antibiotics in the world. There are just over 22 doses of antibiotics prescribed per thousand people, every day. Unlike other developed countries, Australia s usage has declined since 1994 when doctors wrote 26.1 million antibiotic prescriptions. By 1998 that had declined to 24 million prescriptions for Australia s 16 million people.