UMD Researcher Digs Into Antibiotic Resistance at Urban Farms

A few miles from the University of Maryland, Eco City Farms’ Bladensburg outpost sits on 3.5 acres of land that used to be home to three multifamily apartment buildings. Soil that now grows scallions, broccoli and potatoes was exposed to untold pollutants over the years: rainwater runoff, vehicle emissions, microplastics.

Composting plays a key role in Eco City Farms’ efforts to combat these contaminants. Putting organic matter back into the earth can help create richer, healthier soil in which to grow fruits and vegetables. But can it do more— even fight pathogens in the soil that could affect human health?

Ryan Blaustein, assistant professor of nutrition and food science, is working with seven local urban farms to gain a better understanding of the bacteria, viruses and other microbes living in their soil to help ensure their food, which often supplies urban areas short of fresh produce options, grows as safely as possible.

Supported by an award from the Maryland Agriculture Experiment Station, Blaustein is studying antimicrobial resistance in these farms—in other words, the presence of harmful microorganisms that have evolved to survive efforts to kill them. In the worst-case scenario, these “bad” microorganisms could infiltrate fruits and vegetables, then take up residence in people’s guts or on their skin, and defy antibiotics and other medical treatments.

Microbes naturally develop defense systems to compete with each other for resources, building up resistance as part of an “evolutionary arms race,” said Blaustein, who’s also a member of the Microbiome Sciences team that received a UMD Grand Challenges Impact Award. In many cases, this ability to adapt has been positive, contributing to the creation of antibiotics used to treat diseases in humans.

The problem comes when antimicrobial resistance in soil becomes excessive. “We don’t want to promote that beyond what would be ecologically natural,” said Blaustein.

In urban environments, chemicals like lead or arsenic that are more prevalent than in rural areas can put extra stress on microbes in the soil, potentially boosting bad bugs’ drug resistance. Farmers often add organic material, like manure or compost made from food scraps, to counteract these chemicals and other deficiencies in urban soil.

[Related: Springing Into an Edible Garden]

Thomas Fazio, compost manager at Eco City Farms, works with Blaustein on research that examines how composting changes soil microbes. Blaustein’s team collects soil and leafy green vegetables like kale and lettuce from areas that have been treated with compost to analyze levels of total bacteria and antibiotic-resistant bacteria.

The team’s research, which will be published later this year, has shown that properly treated compost is significantly reducing antimicrobial resistance, said Blaustein.

“Grassy areas where we’re not growing anything—those areas have a higher pathogen count than the soil that has been treated with compost,” said Fazio.

Keep the danger of antimicrobial resistance in perspective, Blaustein advises. The risk of people consuming fruits or vegetables that have been tainted with harmful microorganisms is low, while the health benefits of consuming them are high. Concerns about antibiotic resistance shouldn’t stop people from joining a local community garden or starting a vegetable patch in their backyard, as long as they follow guidelines for safe growing. Even the microbes they meet there—most of them, anyway—are beneficial.

“Gardening is a good thing, beyond food production,” Blaustein said. “It’s good to be exposed to most microbes and play in the dirt.”