Streptococcus mitis meningitis in an adult

We report what we believe to be the first case of S. mitis meningitis in an immunocompetent adult with no predisposing factors. A 35-year-old woman presented with a 2 day history of pyrexia, headache, neck stiffness and photophobia. She had no history of previous illness, head injury or recent dental work. She had, however, complained of pharyngitis and a transient macular rash in the week before admission. CSF examination revealed RBCs 0.4 x 10 super(6)/l, WBCs 4.1 x 10 super(6)/l (95% neutrophils). CSF protein and glucose were 55 g/l and 0.5 mmol/l respectively (simultaneous blood glucose was 4.7 mmol/l). Organisms were not seen on Gram stain. Latex agglutination tests (Wellcome Laboratories) for bacterial antigens were negative. CSF culture yielded an aesculin-negative, optochin resistant, alpha-haemolytic streptococcus which was identified as S. mitis (API Strep, Biomerieux). The organism was fully sensitive to penicillin. A similar organism was isolated from a pharyngeal swab. The patient was treated with penicillin for 14 days. She responded within 24 hours. She had no evidence of immunosuppression and serum immunoglobulins were normal. At review after one month she was well with no neurological sequelae.