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K.L. Therese, J.G. Bartell, R. Bagyalakshmi, J.G. Dajcs, D.W. Stroman, H.N. Madhavan; Etiology of Endophthalmitis from Culture–Negative Specimens . Invest. Ophthalmol. Vis. Sci. 2006;47(13):1890.
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© ARVO (1962-2015); The Authors (2016-present)
Characterize the etiology of infectious endophthalmitis specimens from which no microorganisms were recovered yet were PCR–positive using eubacterial or panfungal probes.
Aqueous humor (AH) or vitreous (VIT) samples were collected from 62 patients with clinical signs of endophthalmitis and 9 patients without signs of infection. DNA was extracted and rRNA gene amplified using eubacterial or panfungal primers. Polymicrobic samples produced mixed PCR amplicons, which were separated by denaturing HPLC. All PCR amplicons were sequenced in order to identify microorganisms.
Endophthalmitis: Cultures of the 42 AH samples produced 3 bacterial species and 8 fungal species. From 42 AH samples, 24 were eubacterial PCR positive, 11 were panfungal PCR positive, and 2 were positive for both bacteria and fungi. Species identification of the AH samples revealed 53 bacteria (36% gram–positive and 64% gram–negative) and 11 fungi (3 yeasts and 8 filamentous). Cultures of the 16 VIT samples produced 1 bacterial species and 3 fungal species. From the 16 VIT samples, 8 were eubacterial PCR positive, 5 were panfungal PCR positive, and 1 was positive for both bacteria and fungi. Species identification of the VIT samples revealed 20 bacteria (10% gram–positive and 90% gram–negative) and 5 fungi (2 yeasts and 3 filamentous). Non–endophthalmitis: No bacteria or fungi were cultured or detected from the 3 AH and 6 VIT samples from patients with no signs of endophthalmitis.
Culturing ocular fluids underestimates the actual rate of bacterial endophthalmitis. DNA–based detection provides a better overall understanding of the breadth of organisms present in endophthalmitis. Species–level identification revealed that bacteria were detected in 67% of AH and 50% of VIT extracts versus 8% and 13%, respectively, based upon culturing. In the AH, 36% of the bacteria detected were gram–positive while only 10% were gram–positive in the VIT.
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