Urban Wetlands as Reservoirs of Antibiotic Resistance

Antibiotic resistance poses a growing public health threat, yet the mechanisms underlying this phenomenon remain unclear. In our lab, we study the role of urban storm water in spreading antibiotic-resistant bacteria and, more importantly, antibiotic resistance genes in natural environments where they may re-enter the human community. Our research shows that genes encoding resistance to clinically important antibiotics (e.g., Cipro) wash into California's coast during winter rains and persist at low, but detectable, levels into the dry summer months. Most of these genes are encoded on small pieces of DNA called plasmids that are readily shared among bacteria that come into contact with one another. Thus, the release of plasmid-encoded antibiotic resistance genes into the environment may lead to an overall increase in antibiotic resistance among both environmental and clinical bacteria.

To accomplish this, we use a variety of methods to capture resistance plasmids from urban coastal wetlands as well as liquids and solids from local waste water treatment plants. Once captured, plasmids are characterized for their resistance phenotypes as well as the host ranges in which they are stably maintained and expressed. In collaboration with Drs. Celeste Brown and Eva Top at the University of Idaho, and Dr. Ryan Botts at PLNU, plasmid genomes are fully sequenced and annotated. The result is that we have both the resistance phenotype and the genetic information associated with the resistance. Using this approach, we have so far captured nine novel plasmids, six of which have been fully sequenced.

We are grateful for support from the National Institute of General Medical Sciences (NIH-NIGMS), grant number 1R15GM102995-01A1. Click here to read our specific aims.

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2014 Plasmid Genomics Group

Top row (from left): Chip La Chat, CC Virtue, Kelly Davidson, Joy Walters, Dr. Dave Cummings.
Bottom row (from left): Ryan Echols, Dr. Ryan Botts.

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