A team led by the Centers for Disease Control and Prevention (CDC) yesterday published the details of its investigation into the source of a multistate outbreak of carbapenemase-producing, carbapenem-resistant Pseudomonas aeruginosa linked to artificial tears. The findings appeared in Clinical Infectious Diseases.
The investigation by researchers with the CDC, the Food and Drug Administration (FDA), and several state and local health departments identified a total of 81 case-patients from 18 states in the outbreak, which stretched from May to November 2022 and was originally linked to an ophthalmology clinic in Los Angeles. Nearly a third of the patients (26) were treated at one of three healthcare facilities in three states. Four of 54 case-patients with clinical cultures died within 30 days of culture collection, 4 of 18 patients with eye infections had to have their eyes removed, and an additional 14 suffered vision loss.
Overall, the use of artificial tears was reported by 61 of 70 case-patients with information, and 43 of 56 with brand information reported using Brand A—a preservative-free, over-the-counter (OTC) product manufactured in India. A 1:1 case-control study conducted with 16 case-patients identified in the largest healthcare facility cluster found that cases had five times greater odds of exposure to artificial tears than controls (crude matched odds ratio [OR], 5.0; 95% confidence interval [CI], 1.1 to 22.8).
Trace-back investigation confirms source
Whole-genome sequencing of isolates from case-patients and opened and unopened Brand A bottles showed the isolates were genetically related, and an FDA inspection of the Brand A manufacturing site identified "multiple deficient practices" as the likely sources of contamination.
"The combination of epidemiology and laboratory evidence, including the close genetic relatedness of isolates from case-patients across multiple states and from unopened Brand A product, indicates Brand A artificial tears was the outbreak source," the authors wrote.
They add that proposed legislative changes by the FDA that would strengthen regulatory requirements for sterile manufacturing facility inspection prior to the distribution of OTC products could help prevent similar outbreaks in the future.