Risk factors for Post Operatory Endophtalmitis Caused by Pseudomonas aeruginosa in a Specialized Opthalmologic Center in São Paulo, Brazil

Background: In a previous study we identified that despite the low incidence (0.06%) of Post Operatory Endophtalmitis (POE), P. aeruginosa persisted as the main etiologic agent causing POE after cataract surgery in our institution, with devastating consequences in its evolution.

 

Objective: To identify risk factors for POE caused by P. aeruginosa.

 

Methods: It was carried out a retrospective case-control study including 8 cases and 24 controls operated in the period from 2004 to 2009 at the Centro de Oftalmologia Tadeu Cvintal (COTC), a specialized ophthalmologic center located in the city of S‹o Paulo, Brazil. POE case was defined as an infection restricted to the ocular globe, with at least three of the following post-surgery signs or symptoms: anterior chamber reaction, vitreous cloudiness, low visual acuity, pain, hypopyon, fibrin formation, conjuntival redness and eyelid edema, in which the etiologic agent isolated was P. aeruginosa. Controls were randomly selected among the patients who had been operated at the same days of the cases. The following variables were studied: ethnics, age, gender, diabetes, ocular affection presence at the time of the surgery (as blepharitis, dry eye, dacryocistitis, symblepharon, trichiasis, entropion, corneal ulcers), operated eye, type of anesthesia, surgical shift period, operating room number, surgeon, anesthesiologist, operating room nurse, total surgery duration, phacoemulsification duration, intraocular lens (IOL) type, and use of iris hook, tripan blue, vancomicin or adrenalin added in Balanced Salt Solution (BSS). Potential risk factors were analyzed using univariate methods, and P<0.05 was considered significant.

 

Results: The time from surgery to the first sign or symptoms varied from 2 to 73 days (mean 12; median 3 days), with anterior chamber reaction and low visual acuity as the most frequent sign and symptoms. Men corresponded to 2 cases and 9 controls; women were 6 cases and 15 controls. The mean age was 66 for both cases and controls. The risk factors associated with P. aeruginosa infection were: the surgery done in the operating room number 8 and longer phacoemulsification duration (respectively P=0.003 and P=0.001). Contrary to our expectation, vancomicin use was not identified as a risk factor for this etiologic agent. Specific measures adopted: the operating room involved had its physical structure refurbished and thoroughly washed and disinfected. The surgeons were oriented to reduce as much as possible the phacoemulsification duration.

 

Conclusions: The risk factors associated to P. aeruginosa in our institution were not associated to patients characteristics but to surgical environment and phacoemulsification duration. All these risk factors were appropriated managed to prevent other cases. There were no more cases of P. aeruginosa since 11/2009, when the specific preventive measures were implemented.