The outbreak of extensively drug-resistant bacteria linked to eye drops recalled earlier this year is continuing to grow, the Centers for Disease Control and Prevention says, with 81 cases and four deaths now reported across 18 states.

The figures published Friday by the agency mark the first increase in deaths since March, when the CDC tallied three dead. Thirteen more patients have also since been confirmed, though around half of them were actually from specimens gathered before the February recall of eye drops.

“These cases were confirmed after the recall date due to the time it takes for testing to confirm the outbreak strain and because of retrospective reporting of infections,” the CDC said.

For months, the Food and Drug Administration has urged Americans to stop using two brands of eye drops suspected by investigators to be linked to the outbreak: Delsam Pharma and EzriCare. 

An FDA inspection of the plant in India that had manufactured the products, operated by Global Pharma Healthcare Private Limited, turned up a range of issues, from dirty equipment to missing safeguards, earlier this year.

Testing done on already-opened bottles of EzriCare eye drops turned up the same strain of bacteria driving the outbreak across multiple states. 

In analyzing unopened tubes of a different product from the same company, Delsam Pharma’s eye ointment, the FDA said earlier this year they had found them to be contaminated with bacteria.  

Now the FDA has found bacterial contamination in unopened bottles of EzriCare as well, the CDC says. 

It is unclear what bacteria the FDA found in the unopened bottles. A spokesperson for the regulator did not immediately respond to a request for comment.

Person-to-person spread

Of new cases that have been identified after the recall, the CDC says most were either using brands that had been recalled or involved people living in nursing homes with other previously diagnosed infections. 

Health authorities have warned that the rare strain of bacteria driving the outbreak — a specific variant of Pseudomonas aeruginosa — was spreading person-to-person, especially through contaminated surfaces in hospitals and other health care settings with vulnerable patients.

“We usually find these strains in patients in health care settings, and they’re spreading patient-to-patient through health care workers who maybe forgot to wash their hands, through contaminated medical equipment, or contamination in the health care environment,” the CDC’s Mayora Walters told the “One Health Trust” podcast recently.

While Pseudomonas aeruginosa infections in general are common, Walters said the outbreak’s rare drug-resistant strain — never before seen in the U.S. — and its spread across facilities in multiple states made the situation unusual. 

“At first we had three separate outbreaks in different types of health care facilities, including very different types of health care facilities, and an outpatient eye clinic,” said Walters.

Fourteen people infected in the outbreak have now lost their vision, up from eight previously reported by the CDC. In addition, four patients needed their eyeballs surgically removed.

“Those just seemed to be sort of fairly typical outbreaks of this organism, with the exception of the eye clinic, which was definitely atypical because we’d actually never seen eye infections with this organism before,” she said.