By late 1943, mass production of the drug had commenced - only four years after the first mouse experiments and in spite of the war, a sign of Florey's persistence and determination. By the end of the war, many laboratories were manufacturing the drug, including the Merck, Squibb and Pfizer companies in the US and the Commonwealth Serum Laboratories in Australia. In fact, Australia was the first country that made the drug available for civilian use. However, several strains of bacteria became resistant to penicillin after a few years, through mutation of the cells. To overcome this problem, scientists in the 1950s made artificial penicillin by chemically changing natural penicillin.
Resistant bacteria multiply when non-resistant bacteria die.
Hospitals in Australia and around the world are now seeing the arrival of antibiotic-resistant bacteria due to the overuse of antibiotics, exposing the very young, very old and very sick people to infections and diseases. Florey's father owned a shoe business in Adelaide, having migrated from England for a warmer climate due to his wife's poor health. When she died of tuberculosis, he married Bertha and they had two daughters, followed by Howard. Howard was brilliant at schoolwork and outstanding at sport. He was inspired by his high school chemistry teacher to study medicine at the University of Adelaide.