The number of people with highly drug-resistant bacterial infections linked to contaminated eyedrops has reached 81, the Centers for Disease Control and Prevention reported Friday.

The 81 cases, up from 68 identified in March, include 14 people who have been blinded and four others who had to have their eyeballs surgically removed.

The infections come from a specific strain of Pseudomonas aeruginosa bacteria that has proven difficult, if not impossible in many cases, to control with standard antibiotics.

Though most infections have been limited to the eyes, the bacteria can be fatal when it enters the bloodstream. As of Monday, the CDC said, four people have died.

Now, cases have been discovered in 18 states: California, Colorado, Connecticut, Delaware, Florida, Illinois, North Carolina, New Jersey, New Mexico, Nevada, New York, Ohio, Pennsylvania, South Dakota, Texas, Utah, Washington and Wisconsin.

Many of these conditions were among groups of people living in long-term care facilities, the CDC said.

Symptoms of eye infection include yellow, green or clear discharge, eye pain or discomfort, redness, foreign body sensation, blurred vision and increased sensitivity to light.

Though many patients said they’d used multiple brands of eyedrops, EzriCare Artificial Tears was found to be a common brand among those infected. Opened bottles of the EzriCare eyedrops were also found to harbor the same bacteria found in samples taken from patients.

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