When researchers examined wastewater at ten Swedish hospitals, they found that conditions in the sewage systems favored antibiotic-resistant bacteria.
The emergence of antibiotic resistance is a major threat. Without effective medication, common infections can quickly become life-threatening.
Peeing it out
The researchers studied Karolinska University Hospital and Södersjukhuset in Stockholm, as well as Sahlgrenska University Hospital and Östra Hospital in Gothenburg, among others.
Hospital wastewater favors resistant bacteria because large amounts of antibiotics end up in it, mainly because patients excrete the drugs they have been treated with in their urine. The levels allow resistant variants to thrive in the pipe systems beneath hospitals while non-resistant bacteria die off.
Bacteria in wastewater can then spread, especially when the systems become overloaded during heavy rain. Untreated wastewater is often released into rivers and lakes, and can eventually reach us, says Joakim Larsson, professor of environmental pharmacology at the University of Gothenburg and one of the researchers behind the study.
But he points out that the remarkable thing is not that bacteria spread to humans via sewage. The study's most important finding is that hospital sewage systems provide an almost perfect environment for new forms of resistant bacteria to develop.
Two stand out
The researchers identified two common types of antibiotics that were particularly important: quinolones and beta-lactams. Ciprofloxacin, which is often used to treat urinary tract infections, is one of the quinolones.
Everyone who needs it must receive antibiotic treatment, but if we know which drugs are driving the development of resistance in sewage, we can more easily develop strategies and solutions to reduce the problem, says Joakim Larsson.
This could mean choosing antibiotics that break down faster and are not excreted in urine to the same extent, or finding smart purification systems.
We are working on developing a targeted purification method that makes ciprofloxacin unavailable to bacteria in wastewater, he says.
The study has been published in the journal Nature Communications.
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