Microbiological diagnosis of bacterial endophthalmitis

Abstract

AbstractPurpose The systematic microbiological documentation of endophthalmitis allows the confirmation of the infectious nature of the disease and the possible adaptation of treatment at the individual level and, at the collective level, the epidemiological characterization of the bacterial spectrum of endophthalmitis.Methods different microbiological techniques will be presented: conventional techniques (media), eubacterial PCR, real time PCRResults It is preferable to inoculate intraocular samples into culture media (a paediatric blood culture bottle or in Brain Heart Infusion (BHI) broth) under sterile conditions in the operating room and to transfer the sample intended for PCR into a sterile tube without residual DNA (DNA‐free) and with a screw cap. Bacterial identifications and antibiograms are then obtained using phenotypic methods. Real time PCR is more sensitive than culture, allows the detection and identification of specific micro‐organisms, DNA quantification, and has a faster turn around time (no post‐PCR step). The PCR amplification of 16S rDNA uses consensus primers (panbacterial PCR) and is followed by identification from analysis of 16S rDNA sequence. This technique has the advantages of amplification of DNA from all bacteria, and identification of bacteria difficult to identify phenotypically (e.g. coagulase‐negative Staphylococcus species). However drawbacks are the possible contaminations, the duration (2‐3 days including sequencing), and the impossibility of differentiating mixed bacterial species in the same clinical sample.Conclusion PCR techniques are complementary tools to culture. New techniques of PCR are needed in order to be faster and more sensitive. Genomic characterization of strain virulence of bacteria involved in endophthalmitis will be further studied.