Neonatal invasive Haemophilus influenzae disease in England and Wales: epidemiology, clinical characteristics, and outcome

Abstract

Background: Nontypeable Haemophilus influenzae (NTHi) frequently causes noninvasive upper respiratory tract infections in children but can cause invasive disease, mainly in older adults. An increased burden of invasive NTHi disease in the perinatal period has been reported by a number of studies. Here we describe the epidemiology, clinical characteristics, and outcome of neonatal invasive H. influenzae disease in England and Wales over a 5-year period.

Methods: Public Health England conducts enhanced national surveillance of invasive H. influenzae disease in England and Wales. Detailed clinical information was obtained for all laboratory-confirmed cases in infants aged ≤31 days during 2009-2013.

Results: Overall, 118 live-born neonates had laboratory-confirmed invasive H. influenzae disease: 115 (97%) were NTHi, 2 were serotype f, and 1 was serotype b. NTHi was isolated within 48 hours of birth (early-onset) in 110 of 115 (96%) cases, and 70 of 110 (64%) presented with septicemia. Only 17 mothers (15%) had suspected bacterial infection requiring antibiotics during labor. Few (8/110 [7%]) neonates had comorbidities. The incidence of early-onset NTHi increased exponentially with prematurity, from 0.9 per 100 000 (95% confidence interval [CI], .6-1.4) in term neonates to 342 per 100 000 (95% CI, 233.9-482.7) in neonates born at <28 weeks' gestation (incidence rate ratio, 365 [95% CI, 205-659]; P < .001). Case fatality for early-onset NTHi was 19% (21/110); each additional gestational week reduced the odds of dying by 21% (odds ratio, 0.79 [95% CI, .69-.90]; P < .01). A quarter of neonates who survived experienced long-term complications.

Conclusions: Early-onset neonatal NTHi disease is strongly associated with premature birth and causes significant morbidity and mortality.

Keywords: Haemophilus influenzae; epidemiology; neonatal; outcome.