The Molecular Diagnosis of Endophthalmitis

Endophthalmitis requires rapid microbiological investigations to confirm diagnosis. Identification of the microorganism involved is important for several reasons: to quickly confirm the infectious nature of inflammation, to justify and adapt the intravitreal antibiotic therapy, to rationalize the surgical decision for therapeutic vitrectomy, to precisely determine the epidemiology of the disease, and to reevaluate surgical hygienic procedures. In recent years, a number of assays based on polymerase chain reaction (PCR) have been implemented in microbiology laboratories for diagnosis of infectious diseases: pan-bacterial conventional PCR based on amplification of the 16SrRNA gene, specific PCR and real-time PCR tests developed for detection of specific pathogens, multiplex PCR or real-time PCR, which are variants of these techniques allowing simultaneous detection of multiple DNA targets in a single reaction, and quantitative real-time PCR. The contribution of PCR to the diagnosis of bacterial or fungal endophthalmitis is described. To optimize the detection of microorganisms causing endophthalmitis, it is preferable to obtain an early sample of vitreous and to apply both conventional culture and molecular biology techniques (pan-bacterial PCR or real-time PCR), since the two approaches are complementary. Recent molecular techniques allow rapid and specific microbiological diagnosis, can screen rapidly for the presence of a large number of infectious antigens, and can quantify bacterial loads.