The clinical significance of streptococcal species isolated from cerebrospinal fluid.

Alpha-hemolytic (viridans) streptococci are often isolated from cerebrospinal fluid (CSF); however, the significance of such isolates is poorly understood. In order to clarify the clinical significance of isolating these organisms from CSF, we did a retrospective analysis of 43 patients, from whom eight different species of alpha-hemolytic streptococci were recovered. Eight patients (19%) had significant infections based on bacteriologic, laboratory, and clinical findings. Significant infections were associated with S. sanguis, S. salivarius, S. intermedius, S. faecalis, and S. bovis. Thirty-five patient isolates (81%) from CSF were considered as contaminants, with S. mitis being the most frequently isolated organism (49%). Direct gram stain of CSF sediment, CSF glucose concentration, and CSF cell differential were clearly abnormal in most patients with significant infections, in contrast to patients with streptococci isolated as contaminants. Cultures of the lumbar puncture skin site yielded streptococci and other bacteria, suggesting a possible reservoir for contaminants.