Colorado deluge produced flood of drug-resistance genes

VANCOUVER —The historic 2013 flooding in Colorado left pristine waterways awash in antibiotics and microbial drug-resistance genes, researchers reported November 12 at the annual meeting of the Society of Environmental Toxicology and Chemistry.

In the weeks and months after the disaster, often described as a 1,000-year flood, researchers detected record high levels of drugs in the South Platte River Basin, near the state’s northern border. The drugs, a combination of human and animal antibiotic therapies, were probably swept from agricultural lands and two sewage treatment plants along the river. For the first time, researchers spotted drugs in the headwaters of the river, previously considered pristine.

The researchers, led by environmental scientist Joshua Wallace of the University of Buffalo, saw a spike in the genetic fragments that render microbes immune to particular drugs, compared with preflood levels. Such genes can float freely in the environment or travel within a microbe. The finding raises concern for human health because microbes resistant to common antibiotics may cause infections that are difficult to treat. Whether the spike in resistance genes is due to a deluge of resistance genes or a surge in drug-resistant germs remains unclear.