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Study: Pitt surveillance system detected infection linked to eye drops months before outbreak declared


Earlier this year, the US Centers for Disease Control and Prevention issued an advisory, sounding the alarm for an outbreak of a drug resistant strain of the bacteria Pseudomonas aeruginosa that was connected to the use of artificial tears.

(Image Credit: AdobeStock/Who is Danny)

(Image Credit: AdobeStock/Who is Danny)

The University of Pittsburgh School of Medicine created an infectious diseases surveillance system deployed at a UPMC hospital that successfully flagged cases of a drug-resistant infection spread by eye drops months before an outbreak was revealed by national public health officials.

The findings, published in The Journal of Infectious Diseases,1 were obtained through a hospital-based program called Enhanced Detection System for Healthcare-Associated Transmission (EDS-HAT). The researchers showed the potential of this technology to detect and stop nationwide outbreaks sooner.1

“Our study really showcases the utility of whole genome sequencing surveillance,” senior author Daria Van Tyne, PhD, assistant professor in Pitt Medicine’s Division of Infectious Diseases. “If more hospitals were to use EDS-HAT or a similar increasingly accessible technology, they could head off outbreaks within their walls much faster. And if multiple hospitals share this data with each other and public health authorities, then national outbreaks could be stopped in their tracks.”

According to the University of Pittsburgh news release, whole genome sequencing offered scientists a glimpse of the unique DNA “fingerprints” of pathogens in a sample from a patient with an infection. When the genetic code from samples from two different patients is very closely matched, it means either one patient somehow gave the infection to the other or they both got it from the same source, indicating an outbreak.1

Van Tyne pointed out that UPMC, a nonprofit health care provider with hospitals in Pennsylvania, New York and Maryland, may be the only U.S. hospital system using whole genome sequencing in this way.

In February, the US Centers for Disease Control and Prevention issued an advisory, sounding the alarm for an outbreak of a drug resistant strain of the bacteria Pseudomonas aeruginosa that was connected to the use of artificial tears. According to the CDC, 81 patients were identified across 18 US states with 4 deaths.

According to the University of Pittsburgh news release, Alexander Sundermann, DrPH, lead author of the study and assistant professor in Pitt Medicine’s Division of Infectious Diseases, compared the CDC’s newly released code with whole genome sequencing results kept on file from UPMC’s surveillance. He was able to get a match.1

In October 2022, UPMC detected two cases of the drug-resistant infection through EDS-HAT. This pointed to an outbreak, and led hospital infection preventionists to investigate, but they could not find any commonality between the patients – there was no contact between either patient, they didn’t have the same physicians, didn’t stay in the same rooms and no common hospital equipment had been used. While one patient’s record included the use of artificial tears, the other didn’t mention it. And no public health alert had been issued at that point.

The CDC shared the genetic code, and this proved to be the missing piece of the puzzle that Sundermann and Van Tyne were searching for to unravel the mystery. Both of those cases proved to be a part of an outbreak linked to artificial tears.

After confirming that UPMC had seen cases of P. aeruginosa months before the national alert was issued, Sundermann and Van Tyne were able to take their work a step further, securing the requisite sequences of P. aeruginosa that had been shared. This allowed them to build a “family tree” and trace the bacterium’s origins to samples collected in 2013 and 2018 from India and Nigeria, but not seen in U.S. samples before 2022. According to the university’s news release, their results are consistent with reports that the eye drops were likely contaminated in a manufacturing facility overseas in late 2021 or early 2022.

Sundermann pointed out in the news release that the information from the CDC proved to a breakthrough for researchers.

“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,” he said in the news release. “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.”

The research team also includes Vatsala Rangachar Srinivasa, MPH, Emma G. Mills, BS, Marissa P. Griffith, BS, Kady D. Waggle, BS, Ashley M. Ayres, MBA, BS, Lora Pless, PhD, Graham M. Snyder, MD, MS, and Lee H. Harrison, MD, all of Pitt, UPMC, or both.

The research was funded in part by a National Institute of Allergy and Infectious Diseases grant.

1 Alexander J Sundermann, Vatsala Rangachar Srinivasa, Emma G Mills, Marissa P Griffith, Kady D Waggle, Ashley M Ayres, Lora Pless, Graham M Snyder, Lee H Harrison, Daria Van Tyne, Two Artificial Tears Outbreak-Associated Cases of Extensively Drug-Resistant Pseudomonas aeruginosa Detected Through Whole Genome Sequencing–Based Surveillance, The Journal of Infectious Diseases, 2023;, jiad318 DOI: https://doi.org/10.1093/infdis/jiad318
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