ASEPTIC MENINGITIDES - DETECTION IN CSF O F BACTERIAL-DNA WITH POLYMERASE CHAIN-REACTION

Objective: To develop a diagnostic tool to recognize whether a postope rative meningitis occurring in neurosurgical patients is of bacteriolo gical origin or not, in detecting in CSF bacterial DNA with the polyme rase chain reaction (PCR) technique. Study design : Laboratory study. Patients: Twenty-seven neurosurgical ICU patients associating, in the postoperative period, the CDC criteria of meningitis and a neutrophil polymorphonuclear count over 100 . cells mm(-3) were allocated either into the MB+ group (n = 7) when their CSF culture was positive or in t he MB- group (n = 20) when the culture was sterile. The CSF of 43 neur osurgical ICU patients without postoperative clinical and biological f eatures of meningitis acted as controls. Sixteen specimens out of the 43 were inoculated with bacteria at a known concentration. Methods: Th e CSF specimens of all patients were tested for the presence of eurcar yote DNA using the PCR technique. Beforehand its sensitivity had been assessed using the inoculated CSF of control group: a positive amplifi cation at 20 cycles was equivalent to 10(5) CFU . mL(-1) and a positiv e amplification at 25 cycles to 10(3) CFU . mL(-1) Results: In the 43 sterile control CSF specimens the amplification was negative in all at 20 cycles and in 42 at 25 cycles. In the 16 previously sterile contro l specimens supplemented with bacteria, as well as in the CSF of all 7 patients of MB+ group the amplification was positive at 20 and 25 cyc les. In those of MB- group the amplification was negative in all at 20 cycles, but was positive in 19 out of 20 at 25 cycles. Southern blot with specific procaryote probes was positive with amplification produc ts from CSF of MB+ and MB- groups and negative with control CSFs and h uman DNA. Discussion : The presence of bacteria in CSF of patients sus taining a meningitis can be accurately detected through their DNA. Pos toperative aseptic meningitides may have a bacterial origin. PCR can b e used as a routine technique to provide a diagnosis of bacterial meni ngitis in less than 6 hours. Additionally specific oligonucleotides al low to identify the bacteria in less than 12 hours.