Fatal Meningitis and Sepsis Caused by Nontypeable Haemophilus influenzae

The rates of nontypeable Haemophilus influenzae (NTHi) invasive disease have been increasing since the introduction of the Haemophilus influenzae type b (Hib) vaccine, but its significance in adults is unclear. A 33-year-old man with human immunodeficiency virus (HIV) was admitted for fever and acute confusion. The day prior to admission he presented to another emergency department for nausea, vomiting and diarrhea where he was thought to have food poisoning and was sent home. Ten days prior to admission, his primary physician thought his nasopharyngitis symptoms were due to the common cold. The patient's HIV had been controlled on antiretroviral therapy for the past 3 years; 1 month prior to admission his viral load was undetectable. Laboratory evaluation on admission was significant for elevated lactic acid and CD4⁺ cell count of less than 200. A head computed tomography (CT) was unremarkable, but a lumbar puncture was consistent with bacterial meningitis. Neisseria meningitidis was suspected and the patient was placed on empiric antibiotics. Shortly after admission the patient was intubated and suffered a cardiac arrest. The patient was placed on vasopressor support after circulation returned; a repeat head CT showed increased swelling of his brain. An electroencephalogram (EEG) indicated complete suppression of activity and the patient expired on day 2 of hospitalization. After the patient's death, cerebrospinal fluid (CSF) cultures reported as positive for Haemophilus influenzae (H. influenzae) and sent to the state lab where it was further classified as NTHi, biotype I. NTHi strains can cause invasive disease in adults and should be considered as a potential pathogen for meningitis and bacteremia.