Doctor of Critical Care Medicine Inspira Health, United States
Introduction: Haemophilus influenzae (H.flu) is an uncommon cause of meningitis in adults since the development of the H. flu type B conjugate vaccine. It is therefore presumed that the non-typable strains of H. flu are now associated with invasive infections such as meningitis. Since the development of the vaccine, H. flu only accounts for 1-3% of meningitis cases in adults over 15 years of age in the United States (1). This case report depicts a 52 year old male without significant medical history who developed meningitis due to H.flu.
Description: The patient presented after a recent upper respiratory infection (URI) treated with azithromycin with acute onset of severe headache, photophobia, neck pain, and fever. He reported that he and his family had received all childhood vaccinations. Labs on admission were significant for a white count of 28x103/uL, lactic acid of 2.9 mmol/L. CT of the head revealed sinusitis with complete opacification of the right sphenoid sinus. Lumbar puncture fluid was cloudy with a 92% neutrophil predominance, protein level of 511 mg/dl, and less than 20 mg/dl of glucose. He was started on intravenous vancomycin, ceftriaxone, ampicillin and decadron and admitted to the ICU for the management of sepsis secondary to meningitis. Blood cultures grew beta-lactamase positive H. influenzae type B. MRI showed hyperintensities consistent with meningitis.
Discussion: While H. flu was formerly a contagious pathogen and common culprit of meningitis in children, its incidence, especially in adults, has been on the decline since the development of the H. flu vaccination. This report describes a rare case of H. flu meningitis in an immunocompetent adult. It is possible that disseminated infection could have been prevented with the outpatient administration of amoxicillin-clavulanate rather than azithromycin as it lacks coverage against H. flu. While less common than in children, H. flu can cause disseminated infection such as bacteremia and meningitis in adults and it should not be overlooked as a potential culprit of a localized upper respiratory tract infection or systemic infections.
