Culture was performed for all samples that were positive
or doubtful on direct microscopy. PCR was performed for all
CSF samples that were bloody, or that did not have culture
performed, or that had negative or contaminated culture
results, or discordant results for Pastorex® and culture.
Although 100% specific, culture is easily contaminated in
field conditions and Neisseria, a fragile bacterium, must be
cultured within 2 h of CSF collection. Similarly, microscopy
becomes difficult after more than 2 h delay. The effectiveness
of the PCR technique, however, is not dependent on the
length of time since sample collection