Adult pneumococcal meningitis presenting with normocellular cerebrospinal fluid: two case reports

Normocellular bacterial meningitis is rarely observed in adult patients. We here report two cases of adult patients with pneumococcal meningitis with a normal cerebrospinal fluid leukocyte count and review eight other cases in the literature. Case 1 was a 34-year-old Japanese woman with a history of splenectomy who presented with pyrexia, nausea, headache, and loss of hearing in her right ear. She was in a hypotensive state with no neck stiffness and had a normal mental status at the initial presentation. She became progressively disoriented during out-patient management. A cerebrospinal fluid examination showed a normal leukocyte count despite the presence of Streptococcus pneumoniae, which was detectable with Gram staining. She survived after prompt treatment, but her hearing loss remained. Case 2 was a 62-year-old Japanese man with a history of laryngeal cancer who was transferred to our emergency department after an acute onset of delirium and rapid progression to septic shock. As in Case 1, cerebrospinal fluid examination showed a normal leukocyte count despite the presence of S. pneumoniae, which was detectable with Gram staining. Within 1 hour of arrival, he developed hypotension and subsequent cardiopulmonary arrest, and resuscitation was unsuccessful. These cases imply that a normal leukocyte count in the cerebrospinal fluid does not exclude the possibility of bacterial meningitis. Gram staining of cerebrospinal fluid and immediate administration of antibiotics should be performed in all patients with suspected bacterial meningitis.