Principles and applications of molecular biology techniques for the microbiological diagnosis of acute post-operative endophthalmitis.

The systematic microbiological evaluation 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. Long reserved for research, the use of molecular biology techniques to complement conventional culture techniques has become important for the diagnosis of endophthalmitis in recent years. These new diagnostic techniques are particularly useful for the microbiological study of bacteria that are difficult or impossible to grow because of their intrinsic properties, their presence in only a small inoculum, their sequestration on prosthetic materials, or their inactivation by prior antibiotic treatment. These techniques are based on the polymerase chain reaction (PCR), which allows the amplification and detection of extracted bacterial deoxyribonucleic acid (DNA) that is initially present in minute quantities in an ocular sample. In practice, these conventional or real-time PCRs allow either the a priori detection of bacterial DNA (universal PCR) or the identification of a specific DNA fragment of a bacterial genus or species (specific PCR). New techniques of PCR will allow more rapid bacterial identification and also characterization of genotypic properties, such as genes of virulence or antibiotic resistance.