MATK and listeriosis: The PCR assay for the hyl gene, encoding listeriolysin O, has been reported to be specific and more sensitive than culture after antibiotic therapy has been initiated, with up to 10% of culture negative CSF having a positive PCR result in cases otherwise attributed to listeriosis based on clinical presentation and imaging results.6 The patient presented here is unique in that the CSF obtained at time of presentation resulted in a negative PCR assay but positive culture, demonstrating a rare false-negative PCR result.