Antibiotic Resistance Flourishes in Freshwater Systems

Story by:

McMaster University

First posted on 04-26-2012

Dr. Seuss may have been on to something when he imagined that microscopic communities could live and flourish on small specs of dust, barely visible to the naked eye. In fact, such vibrant communities actually exist in a material with a delightfully Seussical sounding—yet scientific—name: “floc.”

McMaster University researchers discovered that floc, a “goo-like” substance occurring suspended in water and hosting large communities of bacteria, also contains high levels of antibiotic resistance.

“This has important public health implications because the more antibiotic resistance there is, the less effective our antibiotic arsenal is against infectious diseases,” said Lesley Warren, the principal investigator for the study.

Researchers analyzed water and floc samples for trace element concentrations and the presence of 54 antibiotic-resistant genes.

They were surprised to discover that genes encoding resistance to clinically relevant antibiotics were present in floc bacteria at all sites in the study, although resistance varied in intensity based on human influence.

“What this tells us is that antibiotic resistance is widespread in aquatic environments ranging from heavily impacted urban sites to remote areas,” said Warren. “Yet, it also demonstrates that areas with greater human impact are important reservoirs for clinically important antibiotic resistance.”

Floc are vibrant microbial communities that attract contaminants such as trace metals that are markers of resistance, according to Warren, who added that the study of antibiotic resistance in floc has never been done before, “and we are only scratching the surface. The presence of environmental bacterial communities in aquatic environments represents a significant, largely unknown source of antibiotic resistance,” she said. “The better we understand what is out there, the better we can develop policies to safeguard human health as best we can.”