Invasive Haemophilus influenzae Disease at Texas Children's Hospital, 2011 to 2018

Universal vaccination with Haemophilus influenzae type b conjugate vaccines has significantly changed the epidemiology of invasive H. influenzae disease in the United States. We reviewed the epidemiology, clinical features, and outcomes in 61 patients with invasive H. influenzae disease evaluated at Texas Children's Hospital (TCH).

Cases of invasive H. influenzae disease, defined as isolation of the organism from cerebrospinal fluid, blood, synovial fluid or pleural fluid, during 2011 to 2018 among children cared for at TCH in Houston, TX, were included.

We identified 61 cases of invasive H. influenzae disease in children ≤18 years of age. The overall hospitalization rate due to invasive H. influenzae disease increased between 2011 and 2018 (0 vs. 0.64/1000 hospitalizations; P = 0.019). The majority (80%) of infections occurred in children <5 years of age. Of the 61 H. influenzae infections, 24 (39.3%) infections were caused by nontypeable H. influenzae strains, 18 (29.5%) infections were caused by H. influenzae type a, 12 (19.7%) infections were caused by H. influenzae type f, 3 (4.9%) infections were caused by H. influenzae type e and 4 (6.6%) isolates were not typed. A total of 78.7% of the isolates were β-lactamase negative. The most common clinical presentations were bacteremia without a source, pneumonia and meningitis.

The hospitalization rate for H. influenzae invasive disease increased over an 8-year period at TCH. The overall trend was mainly driven by an increasing number of invasive infections caused by nontypeable H. influenzae and H. influenzae type a. Morbidity was substantial, especially in meningitis cases.