At hospitals, diseases are often transmitted among patients — but patients might actually be exposed to these infections on their way to the hospital.

Using DNA analysis methods being popularized by a lab at Drexel, a group of medical and public health researchers at Weill Cornell Medicine are tracking the illness-causing agents hitching a ride in ambulances.

Associate Professor Gail Rosen and her Ecological & Evolutionary Signal-Processing & Informatics Laboratory analyzed DNA of nearly 400 samples from 137 ambulances in 19 cities in six states. The methods, based on “whole-genome shotgun sequencing,” provide a thorough genetic-level look at collections of organisms — without having to collect, identify and count every organism in the group.

While the ambulance microbiomes differed by region, one of the findings the researchers discovered was an increase in antimicrobial resistant bacteria in ambulances from lower-latitudes in the east.

“The methods we developed can be used for forensic analysis,” Rosen says. “For example, we found that stethoscopes were more likely to have microbes that eat cleaning agents. It was fun to get a peek into microbial communities’ lives, especially those that we cannot culture, to try to see how climate and geographic areas may affect ambulance microbiomes.”