Clusters of postoperative endophthalmitis caused by non-tuberculous mycobacteria and Pseudomonas aeruginosa: diagnostic and sterilization challenges

To describe two consecutive postoperative endophthalmitis clusters—one caused by non-tuberculous mycobacteria (NTM) and the other by Pseudomonas aeruginosa—linked to a defective autoclave sterilization process in a single tertiary eye hospital in India.

This retrospective study reviewed 25 cases of postoperative endophthalmitis between April and August 2024. The first cluster included 21 eyes infected with NTM, while the second involved 4 eyes infected with P. aeruginosa. Clinical data, microbiological findings, management strategies, and outcomes were analyzed. Environmental cultures and sterilization protocols were also reviewed to identify the source of contamination.

The first cluster presented insidiously, with symptoms appearing on average 40.4 ± 7.3 days postoperatively. Cultures revealed Mycobacterium abscessus, M. fortuitum, or M. brisbaneii in 18 of 21 eyes. All patients underwent pars plana vitrectomy with intravitreal vancomycin, ceftazidime, and dexamethasone, followed by oral linezolid. Visual recovery was favorable in most cases (20/21 eyes), with only one progressing to phthisis. The second cluster, occurring shortly thereafter, involved four cases of acute postoperative endophthalmitis caused by P. aeruginosa. Three eyes recovered useful vision, while one developed phthisis. Investigation revealed a defective autoclaving protocol as the common source of infection.

These consecutive clusters highlight how minor deviations in sterilization protocols, compounded by high ambient humidity, can precipitate catastrophic outbreaks. Prompt identification, aggressive treatment, and reinforcement of sterilization standards prevented recurrence and resulted in excellent outcomes.