New fast test to diagnose bacterial endophthalmitis

A newly-developed fast real-t PCR (f-real-t PCR) test is an effective and much more rapid way to diagnose bacterial endophthalmitis (BE), concluded a study published online ahead of print by the British Journal of Ophthalmology.

Pablo Goldschmidt, of the Laboratoire du Centre National d’Ophtalmologie des Quinze-Vingts, France, and colleagues examined specimens of vitreous fluid (VF) and aqueous humour (AH) cells from endophthalmitis, infected with bacteria or non-infective disorders and control to determine if the f-real-t PCR testing method they had developed could overcome the barriers most commonly associated with BE testing, including insufficient VF or AH, PCR cross-contamination and culture insensitivity, to identify the bacteria and Genera of the DNA that had been extracted from the specimen cells. The team compared the diagnoses with those from direct microscopic examination and culture.

The f-real-t PCR showed no cross-reactivity with fungi even though it detected ≥0.01 CFU Bac/µl and had a 100% correlation with culture positive results. Of the BE samples, 60% tested culture positive; with f-real-t PCR, this was 90%. Within 90 minutes, the f-real-t PCR detected and quantified the presence of Bac, Staphylococci, Streptococci, Haemophilus, Pseudomonas, Enterobacteria, Acinetobacter, Propionbacteriacae and Corynebacteria. The non-infective cells tested negative.

The team therefore concluded that their f-real-t PCR test reduced substantially the hours or even days required for cultures, and provided a more accurate result. The test’s developers now plan to run a larger series of samples to assess the utility of the test.