Polymerase chain reaction (PCR) for rapid detection of cerebrospinal fluid shunt or ventriculostomy infections

Abstract

Abstract Introduction: Infections of cerebrospinal fluid (CSF) shunts or ventriculostomies are common complications that are associated with significant morbidity and mortality. Detection of infection may be difficult or delayed as it requires colonial growth of microorganisms in culture medium. PCR provides rapid and accurate detection of bacterial DNA. Methods: Under Institutional Review Board approval (X030403011), 50 samples of CSF samples were collected (many serially) from adult patients who underwent either shunt tap or routine surveillance cultures of their external ventricular catheter. CSF was evaluated by standard culture techniques and by PCR. For PCR, frozen samples of CSF were thawed on ice and DNA extracted, purified and amplified for 16S rRNA using primers 16S-Forward and 16S-Reverse of conserved sequence region of all bacteria. DNA was PCR amplified for 30 cycles (denaturation at 94degC/15sec, annealing at 54degC/15sec, extension at 72degC/30sec) after initial denaturation at 94degC/5min. One microliter of the 1st PCR product was subjected to nested PCR using primers specific for Gram+ve, Gram−ve bacteria and P. acnes, S. aureus, and MRSA. Results: For 13/50 specimens, both culture and PCR were positive. For 18/50 specimens both PCR and culture results were negative. For 19/50 specimens, cultures were negative and PCR was positive. Conclusions: There were no positive culture results with negative PCR and the negative culture/positive PCR cases occurred after prolonged iv antibiotics. These preliminary data suggest that PCR is a highly sensitive, rapid and potentially useful modality for the detection of CSF shunt or ventriculostomy infection.