Spontaneous Meningitis Due to Streptococcus salivarius Subsp. salivarius: Cross-reaction in an Assay with a Rapid Diagnostic Kit that Detected Streptococcus pneumoniae Antigens

Abstract

Streptococcus salivarius subsp. salivarius occasionally causes meningitis associated with iatrogenic or traumatic events. We herein describe a case of meningitis caused by this organism in a patient without any apparent risk factors. In an assay of the patient's cerebrospinal fluid, cross-reaction occurred with Streptococcus pneumoniae antigen-coated latex particles in the Pastorex^TM Meningitis Kit. In the in vitro assays, three of the five clinically isolated S. salivarius strains showed cross-reactions with the kit, indicating that these strains expressed pneumococcal antigen-like antigens. This case shows that meningitis caused by S. salivarius can occur spontaneously and it may sometimes be misdiagnosed as S. pneumoniae infection.