NEW YORK (AP) — The United States (US) health officials reported another death and several more cases of vision loss from illnesses linked to eyedrops tainted with a drug-resistant bacteria.

The bacteria has infected 81 people, including four who died and 14 who lost vision, the Centers for Disease Control and Prevention said Friday. That’s up from three deaths and eight cases of vision loss reported in March. The CDC also said four people have undergone surgery to remove an eyeball due to the infections.

The outbreak is considered particularly worrisome because the bacteria driving it — Pseudomonas aeruginosa — is resistant to standard antibiotics.

Investigators say most of the patients had used certain brands of eyedrops, and products from EzriCare and Delsam Pharma were recalled in February. At least seven patients were diagnosed after the recall.

After the recall, US health inspectors visited the plant in India that made the eyedrops and uncovered problems with how the drops were made and tested, including inadequate sterility measures.

Cases have been reported from 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.