Christophe Chiquet, (Grenoble, France), Pierre-Olivier Lafontaine, MD (Dijon, France), Pierre-Loic Cornut, MD (Lyon, France), Yvonne Benito, (Lyon, France), Karine Palombi, MD (Grenoble, France), Gilles Thuret, MD, PhD (Saint-etienne, France), Fr├ęderic Rouberol (Lyon, France), Catherine Creuzot, MD (Dijon, France), Jean-Paul Romanet (Grenoble, France), Francois Vandenesch, MD, PhD (Lyon, France)

PURPOSE:

To improve identification and speciation of bacteria involved in acute endophthalmitis after cataract surgery, using polymerase chain reaction (PCR) technique.

METHODS:

This prospective and multicenter study (2004-2005) includes, 82 patients (mean age 72 years, 1.7-96), with endophthalmitis after cataract surgery. In emergency, an anterior chamber puncture (n= 67) and/or a vitreous puncture (n= 23) were performed under aseptic conditions and were associated with intravitreal injection of antibiotics. Aqueous humor and/or vitreous samples were collected: 100 microL for standard culture (Brain Heart Infusion) and 150 microL for PCR. In 49 patients (60%) a posterior vitrectomy was performed 1-5 days after the first intravitreal injection of antibiotics and vitreous samples were analysed using the same techniques.

RESULTS:

Microbiological diagnosis is performed on aqueous humor samples in 46% (PCR 35%, cultures 38%) and on vitreous samples in 65% (PCR 64%, cultures 43%). The analysis of the vitreous from vitrectomy shows that the identification of the bacteria was done in 65%, always with PCR (all cultures were negative). Considering aqueous humor and vitreous samples (puncture and vitrectomy), the infectious agent was identified in 66% of the cases. Bacteria were Gram positive in 96% out of the cases (coagulase negative micrococci 48%, S. Aureus 9%, Streptococcus 26%, Haemophilus 1.8%, Proteus 1.8%). A coinfection with
two bacteria is reported in 2 cases. The correlation between both techniques is excellent.

CONCLUSION:

In acute endophthalmitis after cataract surgery, this large series shows a higher proportion of Gram positive bacteria than previously reported. The association of culture and PCR improves the identification of the causative pathogens in the vitreous from biopsy or vitrectomy. PCR performed on vitreous samples is more effective for the bacterial identification than aqueous humor.