This study in the March issue of Ophthalmology reports on the outcome of an investigation into an outbreak of P. aeruginosa endophthalmitis that occurred in 11 patients after cataract surgery during a one-month period. This is believed to be the first study to identify the contamination of hydrophilic IOLs preserved in a solution as the source of post-cataract surgery endophthalmitis.
The patients developed acute postoperative endophthalmitis after uneventful cataract surgery with implantation of hydrophilic acrylic foldable IOLs preserved in a solution (John Fowler Ocular Lenses Pvt. Limited, Aurangabad, India) at a tertiary eye care center in Hyberabad, India, between September 6 and 29, 2010. Aqueous and vitreous samples showed gram-negative bacilli in the smears of eight of 11 eyes. Cultures grew Pseudomonas (P.) aeruginosa in five of 11 eyes.
Among the samples from various surveillance specimens cultured, only the hydrophilic acrylic IOLs and their solutions grew P. aeruginosa, with an antibiotic susceptibility pattern identical to the clinical isolates.
The outbreak of postoperative endophthalmitis involved four different operating rooms, multiple surgeons and random cases. All of the afflicted cases had the common factor of implantation of an IOL made by the same manufacturer.
The authors say that clustering of the isolates was close enough to explain their clonal expansion over a short period (23 days). This observation is supported by negative smears and cultures from other surveillance specimens. The hospital discontinued using these IOLs and endophthalmitis did not recur.
Final visual acuity improved to 20/50 or better in eight of 11 patients (72.7 percent). One patient developed retinal detachment but was treated successfully. Two other patients progressed to phthisis bulbi. Increased inflammation was noticed in six of the 11 patients on day one. They were treated immediately, and all improved.
The authors conclude that early detection and intervention and a planned approach during the outbreak helped to achieve good visual and anatomic outcomes, even though the offending organism was identified as P. aeruginosa.
They recommend inclusion of cultures from various IOLs, especially hydrophilic lenses, as part of hospital infection committee surveillance protocols, and using molecular biology techniques, such as ERIC-PCR, to confirm the source of infection.
They say it remains unclear how the pathogen found its way into the IOL solution bottle. The IOL package was intact before opening and all of the lenses were used before their expiration date. A possible explanation is that the organism entered during the packing of bottles containing the solution or it escaped the sterilization process. A breach in the sterilization protocol by the manufacturing company is another potential cause.