Early Detection: University of Pittsburgh System Identifies Eye Drop-Related Infection

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Researchers from the University of Pittsburgh School of Medicine reported the early detection of a drug-resistant infection linked to eye drops. This discovery was flagged months prior to an official outbreak announcement by national public health officials. The study, recently published in The Journal of Infectious Diseases, used the Enhanced Detection System for Healthcare-Associated Transmission (EDS-HAT), pointing to the efficiency of the system in preemptively identifying potential outbreaks.

Daria Van Tyne, Ph.D., assistant professor in Pitt Medicine’s Division of Infectious Diseases and the study's senior author stated, “Our study really showcases the utility of whole genome sequencing (WGS) surveillance.” This technique allows for the identification of the unique DNA structure of pathogens from infected patient samples. Close matching genetic codes from different patient samples can suggest a single source, hinting at an outbreak.

Currently, UPMC, a health care provider operating in Pennsylvania, New York, and Maryland, is uniquely using WGS in this manner, as per Van Tyne's knowledge.

The U.S. Centers for Disease Control and Prevention (CDC) warned of an outbreak of a drug-resistant bacteria, Pseudomonas aeruginosa, linked to artificial tears on February 1, 2023. This outbreak affected 13 states, causing one death and numerous permanent vision loss cases. In April 2023, the CDC made the genetic code of the outbreak strain public.

Alexander Sundermann, Dr.PH., the study's lead author, identified a match between the CDC’s disclosed code and UPMC’s surveillance data. UPMC had detected two cases of this infection in October 2022. Despite thorough investigation, no evident connection between the two patients was established at that time. It was only after the CDC's data disclosure that the cases at UPMC were linked to the artificial tears-related outbreak.

Sundermann and Van Tyne took their study further, constructing a genetic "family tree" of P. aeruginosa. They traced the bacterial origin to samples from 2013 and 2018 found in India and Nigeria. The bacterium wasn’t identified in U.S. samples until 2022. This timeline aligns with reports indicating contamination of the eye drops in an overseas manufacturing facility in late 2021 or early 2022.

“It took the CDC sharing data on the outbreak strain for us to finally be able to connect the dots and see that our patients were part of the national outbreak,” Sundermann stated. “Imagine how much faster we all could have been aware of this outbreak if more hospitals were performing whole genome sequencing surveillance and feeding their results into a centralized public database. We found our first case shortly after those contaminated eye drops likely started being used in the U.S.—months before the CDC’s alert—but without another case, we had no way to know there was an outbreak.”