Drug-resistant microbes - often dubbed "superbugs" - evolved following the introduction of antibiotics in the 1940s.
Antibiotics work by attacking a particular part of bacteria which causes disease. However, microbes evolve and mutate very quickly and if one develops which can survive a particular type of attack, it will thrive and often achieve "superbug" status while its more "normal" fellow microbes die.
Numerous changes have been made to the composition of drugs to thwart resistant microbes but the development of various kinds of "superbugs" has picked up in the past 10 years. At the same time, the development of new types of antibacterial drugs, able to kill the newly evolving "superbugs", has slowed.
With the evolution of "superbugs" threatening to outwit our capacity to deal with them, public health bodies are advocating a major emphasis on eliminating excessive use of antibiotics.
Public education is a key part of this work. Research by Prof Colin Bradley of University College Cork suggests patients with minor conditions such as colds will go to GPs who are prepared to prescribe antibiotics in preference to GPs who refuse.