The Centers for Disease Control and Prevention (CDC) issued a health alert Wednesday warning people to stop using eye drops that have been linked to an outbreak of drug-resistant infections. The outbreak has impacted at least 55 people in 12 states. One death has been reported as of press time.

“Most patients reported using artificial tears. Patients reported more than 10 different brands of artificial tears, and some patients used multiple brands. The majority of patients who used artificial tears reported using EzriCare Artificial Tears, a preservative-free, over-the-counter product packaged in multidose bottles,” the CDC said in its health alert. “CDC laboratory testing identified the presence of the outbreak strain in opened EzriCare bottles with different lot numbers collected from two states.”

In a Wednesday statement, EzriCare said it was “not aware of any testing that definitively links the… outbreak to EzriCare Artificial Tears.” However, the company added it “immediately took action to stop any further distribution or sale of EzriCare Artificial Tears.”

“To the greatest extent possible, we have been contacting customers to advise them against continued use of the product,” EzriCare said in the statement. “We also immediately reached out to both CDC and FDA and indicated our willingness to cooperate with any requests they may have of us.”

The eye drop-related drug-resistant infection outbreak the CDC is warning about is just the latest example of what health experts call antimicrobial resistance (AMR). AMR can develop when bacteria, viruses, fungi and parasites no longer respond to medicines used to treat them.

A 2022 study published in the Lancet found roughly 4.95 million deaths were associated with AMR. At least 1.27 million people died as a direct result of drug-resistant bacterial infections.

“AMR is a leading cause of death around the world, with the highest burdens in low-resource settings,” authors of the study wrote. “Understanding the burden of AMR and the leading pathogen–drug combinations contributing to it is crucial to making informed and location-specific policy decisions, particularly about infection prevention and control programs, access to essential antibiotics, and research and development of new vaccines and antibiotics.”

The Associated Press and Scientific American contributed to this report.