The environmental origins of antibiotic resistance

Antibiotic resistance is one of the most serious issues facing medicine in the 21st century. Resistance genes are often spread by integrons, a genetic element discovered in the late 1980s by researchers from Macquarie University and the CSIRO.

In 2000, a research team led by Hatch Stokes and Michael Gillings began to investigate where integrons came from. They quickly discovered that integrons were highly diverse, occurred in all natural environments, and commanded access to an unprecedented number of novel genes. The team showed that these properties allowed integrons to emerge from environmental sources and invade human pathogens, where they gradually accumulated genes for resistance to all known antibiotic classes.

Integrons are now found in 70 per cent of pathogens and even in the “good” bacteria associated with humans. As a consequence, these integrons and their resistance genes pollute natural environments via human waste streams. The notion of genes as pollutants, and their consequences for human welfare have been explored in recent publications from the group.

As a result, concern about the effects of pollution with antibiotic resistance genes is increasing world-wide.

This research changed how we view antibiotic resistance, showing that it is best tackled through ecological and evolutionary frameworks. Ongoing research tracks the fate of integrons in the environment, where they continue to accumulate new virulence genes and colonise new animal hosts.

These pollutant integrons have clear potential to transform benign environmental bacteria into newly emerging pathogens. The Macquarie team is identifying these before they return to cause disease in humans.

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