The U.S. Centers for Disease Control and Prevention says it’s investigating a drug-resistant strain of bacteria that caused severe injuries in 68 patients, including three deaths, across the U.S.

The CDC says most of the patients infected with Pseudomonas aeruginosa reported using artificial tears or eyedrops.

Ten different brands of ophthalmic drugs were involved in these cases, the CDC said. But the most common was Ezri Care Artificial Tears, which the Food and Drug Administration warned consumers to stop purchasing last month.

The CDC confirmed a matching strain of Pseudomonas aeruginosa in opened bottles of the product and says it will test unopened bottles to test whether contamination occurred during manufacturing.

The FDA said in February that Ezricare’s parent company, an India-based pharmaceutical provider named Global Pharma Healthcare, had failed to provide appropriate microbial testing of its over-the-counter eye product. The same was true of another of the company’s products, Delsam Pharma Artificial Eye Ointment, which the company voluntarily recalled shortly after.

The FDA said Global Pharma failed to use adequate, tamper-evident packaging and distributed the drugs without proper preservatives.

Global Pharma did not immediately respond to NPR’s request for comment.

Two additional companies, Apotex Corp. and Pharmedica USA, recalled eyedrop products in February, though products from those companies had not been linked to infections at the time.

Common symptoms of the bacterial infection include discharge from the eye, redness of the eye or eyelid, blurry vision, a sensitivity to light and eye pain.

In the most extreme cases, the infection can spread to other parts of the body, including the bloodstream. Three people have died due to infections, the CDC said. At least eight others have experienced vision loss and four have undergone enucleation — the surgical removal of the eyeball.

Infections are generally treated with antibiotics, but the bacteria are becoming increasingly resistant to multiple drugs. The CDC does not recommend patients undergo testing for infection unless they have symptoms.

The CDC says infections caused by Pseudomonas aeruginosa are relatively common in hospitals. At least 37 of the infections of the eyedrop-linked strain were connected to four health care facilities, the CDC said.

In 2017, a drug-resistant strain of the bacteria was believed to have caused an estimated 32,600 infections among hospitalized patients in the U.S., continuing a downward trend from 46,000 in 2012, the CDC said in an informational tip sheet.

  infection, virus