Case Presentation: 62-year-old female with a past medical history of diabetes mellitus and breast cancer in remission presented to the emergency department (ED) with complaints of intermittent frontal headache for 2-3 weeks progressing to 1 day of fever, altered mentation, aphasia, and vomiting. In the ED, patient was afebrile with stable vital signs. Initial labs were significant for WBC 24.7 with 32% bands. CT head without contrast was unremarkable. Patient was admitted for acute metabolic encephalopathy concerning for meningitis. She was started on empiric ceftriaxone, vancomycin, ampicillin and acyclovir. Infectious disease and neurology were consulted. Patient underwent lumbar puncture with cerebrospinal fluid (CSF) showing 5833 WBCs, 75% neutrophils, 222 RBCs, protein 181, and glucose 93 – consistent with bacterial meningitis. PCR was negative. Empiric antibiotics were continued. Few days later, patient revealed a 3 month history of copious clear drainage from left nostril with forward bending raising suspicion for nasal CSF leak. Nasal drainage was positive for glucose highly suggestive of CSF. Subsequently, blood cultures resulted positive for Streptococcus salivarius. As CSF culture was negative, 16S ribosomal RNA PCR for S. salivarius was tested and returned positive. Repeat CT head and subsequent MRI failed to identify skull defects. Therefore, it was concluded that patient’s S. salivarius meningitis and bacteremia were the result of a spontaneous nasal CSF leak. Patient was referred for neurosurgical evaluation. However, CSF leak had spontaneously resolved and surgical intervention was not deemed necessary. Patient was discharged on IV ceftriaxone to complete a total of 14 days of treatment.
Discussion: Streptococcus salivarius is a group D streptococcus that colonizes oral mucosa few hours after birth. It is predominantly found in the oral cavity, upper respiratory tract and digestive tract. As a commensal organism, it rarely causes invasive infections in immunocompetent patients. However, S. salivarius meningitis is increasingly recognized in recent literature – although still exceedingly rare. 60% of cases are associated with iatrogenic causes such as spinal anesthesia or myelography. Less than 15 reported cases are related to CSF leaks. A rapid test used for screening of a CSF leak is glucose content determination. CSF fluid should have a moderate glucose content whereas nasal drainage has nearly none. Confirmatory testing is done using beta-2 transferrin, a protein found only in the brain. In over 90% of reported cases, CSF culture was positive for S. salivarius; only a minority of cases required the rRNA gene PCR used in this case. For our patient, without known risk factors, clinical suspicion was high due to concurrent S. salivarius bacteremia. Additionally, high-resolution CT scan is the imaging modality of choice for detecting skull base defects. The lack of bony defects in this case indicated a spontaneous leak. Treatment for S. salivarius meningitis includes a beta-lactam antibiotic, penicillin or cephalosporin. No specific duration of treatment is established however average length reported to date is 14 days.
Conclusions: Streptococcus salivarius meningitis is a rare cause of bacterial meningitis that accounts for less than 100 published cases. Within these cases, those related to a CSF leak are even more scarce. In patients without known trauma or recent surgical intervention, early clinical suspicion is the key to diagnosis and prevention of life-threatening complications.