Outbreak Investigation of Pseudomonas aeruginosa Endophthalmitis Following Cataract Surgery in a Private Ophthalmology Clinic in Korea

Postoperative endophthalmitis is a rare but severe complication of cataract surgery that may lead to significant visual impairment and can occasionally present as clusters or outbreaks linked to lapses in infection control. On 29 October 2025, three cases of postoperative endophthalmitis following cataract surgery at an ophthalmology clinic (Clinic A) in Yeongju, Republic of Korea, were reported to public health authorities. All cases were confirmed as Pseudomonas aeruginosa (P. aeruginosa). An epidemiological investigation was conducted to identify the source and transmission route; all 54 patients who underwent cataract surgery at Clinic A in October 2025 (62 procedures, including eight bilateral cases) were included. Infection control practices were assessed through on-site inspection, staff interviews, medical record review, and telephone surveys. Environmental samples were collected and cultured selectively for P. aeruginosa. Isolates were analyzed using pulsed-field gel electrophoresis (PFGE) to assess genetic relatedness. Among 54 surgical patients, three developed endophthalmitis (attack rate: 5.6%). All cases occurred in patients operated on 23 October by the same surgeon; no additional cases were identified. P. aeruginosa was isolated from all three patients. Of 45 environmental samples, three were positive: the laundry room drain, the sink drain in the local anesthesia room, and the interior of cassette No. 2 and instruments within the operating room steam sterilizer. PFGE showed 95.7% band pattern similarity between patient isolates and those from the sterilizer. This outbreak was attributed to P. aeruginosa, with the steam sterilizer identified as the most probable source. Inadequate infection control and sterilization practices likely contributed. These findings highlight the critical importance of strict sterilization monitoring and adherence to infection prevention and control practices to prevent recurrence.