Primary influent (untreated) municipal sewage reflects the gut microbiome of the local population. By collecting these samples over time, we can measure changes in the resistance capabilities of commensal bacteria living within the humans in our community.

We use selective and differential media to gauge the response of the Enterobacterales (the group that contains E. coli) as a proxy for the organisms often found in our guts. We challenge them with a variety of antibiotics and measure growth compared to a no-Antibiotic positive control.

Using quantitative PCR, we can estimate the number of resistance genes in our sewage samples. This helps corroborate the results of our culture-based experiments and can be applied to any of our archived DNA samples.