Bacterial Meningitis Caused by β-lactamase Non-producing Ampicillin-resistant Haemophilus influenzae Type f in an Immunocompetent Woman

Invasive Haemophilus influenzae disease among adults in Japan during 2014-2018

PURPOSE

We describe the epidemiology of invasive Haemophilus influenzae disease (IHD) among adults in Japan.

METHODS

Data for 200 adult IHD patients in 2014-2018 were analyzed. The capsular type of H. influenzae was determined by bacterial agglutination and polymerase chain reaction (PCR), and non-typeable Haemophilus influenzae (NTHi) was identified by PCR.

RESULTS

The annual incidence of IHD (cases per 100,000 population) was 0.12 for age 15-64 years and 0.88 for age ≥ 65 years in 2018. The median age was 77 years, and 73.5% were aged ≥ 65 years. About one-fourth of patients were associated with immunocompromising condition. The major presentations were pneumonia, followed by bacteremia, meningitis and other than pneumonia or meningitis (other diseases). The case fatality rate (CFR) was 21.2% for all cases, and was significantly higher in the ≥ 65-year group (26.1%) than in the 15-64-year group (7.5%) (p = 0.013). The percentage of cases with pneumonia was significantly higher in the ≥ 65-year group than in the 15-64-year group (p < 0.001). The percentage of cases with bacteremia was significantly higher in the 15-64-year group than in the ≥ 65-year group (p = 0.027). Of 200 isolates, 190 (95.0%) were NTHi strains, and the other strains were encapsulated strains. 71 (35.5%) were resistant to ampicillin, but all were susceptible to ceftriaxone.

CONCLUSION

The clinical presentations of adult IHD patients varied widely; about three-fourths of patients were age ≥ 65 years and their CFR was high. Our findings support preventing strategies for IHD among older adults, including the development of NTHi vaccine.

Haemophilus influenzae Non-type b Infection in an Adult Patient with Systemic Lupus Erythematosus

A 40-year-old man with systemic lupus erythematosus taking consecutive oral corticosteroids developed a high-grade fever and disorder of consciousness following acute rhinitis. Haemophilus influenzae type f (Hif) was found and isolated from the blood and cerebrospinal fluid by culture, leading to a diagnosis of meningitis. The prevalence of H. influenzae type b (Hib) infections has decreased due to routine immunization. As a result, the prevalence of invasive non-Hib, including Hif infection, is increasing as a common H. influenzae infection in children and adults. Physicians should be aware of non-Hib H. influenzae infection, even though the Hib vaccine is widely used in Japan.