Seagull Droppings in Drug Development? Why Not!

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Andrew Holbrooke

Researchers have all kinds of sophisticated ways of tracking antibiotic resistant bacteria. Like biological CSI investigators, they use the bugs’ genetic fingerprints and knowledge of their favorite host haunts to learn more about how the bugs manage to thwart our pharmaceutical defenses, and how worried we should be that these drug-based barriers are reaching their limit. Occasionally, their search takes them to some unusual resources. Such as seagull droppings.

Yes, it turns out that the dockside and windshield-marring deposits might actually be good for something. For Gilberto Igrejas, a bioengineer at University of Trás-os-Montes and Alto Douro in Portugal and this team, the fecal samples proved to be rich informants on the genetic tools that a particular family of bacteria, enterococci, use to overcome the destructive presence of antibiotic medications. Enterococci are part of the microbial universe in the gut of both animals and humans, working, in most cases, to help digest food and neutralize certain toxins. But they can cause life-threatening infections as well, particularly in hospitals, and increasingly, more of these strains are resistant to the last-resort antibiotic vancomycin. In fact, these gut microbes may serve as reservoirs for resistance to antibiotics, and feces may operate as carriers for spreading these super-strains around. (More on New Weird Source of Antimicrobial Drugs: Cockroach Brains?)

Igrejas found in his study of 57 seagull dropping samples that 10% of them contained such resistant strains of the bacteria. While these wild birds normally inhabit the isolated preserve, he says they also occasionally fly to a nearby coastal towns where they feast on human garbage. And that is likely where the gulls are picking up the antibiotic-resistant bacteria. The genetic changes Igrejas’s group found were typical of alterations made by bacteria under pressure by the drugs to become resistant.

What excites the scientists is that the work also revealed some new proteins that are helping the bugs to bypass the drugs. When faced with the stress of battling an antibiotic drug, the bacteria tend to produce surface proteins on their cell membranes that can either bind and neutralize the medications or keep the drugs from infiltrating the cell. Better knowledge of these stress responses, says Igrejas, can give drug-makers new targets for developing more effective medications. And if that happens, we’ll have the seagulls—and their droppings—to thank.

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