Haemophilus influenzae: a potent perinatal pathogen disproportionately isolated from Indigenous women and their neonates

Abstract

Background: Nontypeable Haemophilus influenzae (NTHi) bacteraemia in pregnant women is strongly associated with pregnancy loss and preterm delivery. However, the clinical significance of isolation of NTHi from nonsterile sites is unknown.

Aims: To examine the hypothesis that isolation of NTHi from any specimen is associated with adverse perinatal outcomes and to investigate the impression that NTHi is disproportionately isolated from indigenous women and their neonates.

Materials and methods: Cases where NTHi was isolated from maternal, fetal or neonatal specimens during the period from 1 July 1997 to 1 July 2009 were identified. Demographic and clinical data were extracted from case notes. Histopathological material was re-reviewed by a perinatal pathologist. Demographic and clinical features of the affected group were compared with the hospital obstetric population.

Results: NTHi was isolated from maternal, fetal or neonatal specimens in 97 pregnancies. Two women had NTHi isolated during different pregnancies. Two mothers and 10 neonates were bacteraemic. Indigenous women comprised 28% of pregnancies where NTHi was isolated, compared with 6% of the hospital obstetric population (P < 0.001). Pregnancy loss occurred in six cases (6%). Median gestation at delivery was 33 weeks. Of 96 liveborn neonates, 88 (92%) required admission to a neonatal special care unit. Four liveborn neonates died (4%). Chorioamnionitis was confirmed by histology in 31/33 (93.9%) of placentas examined.

Conclusions: Isolation of NTHi occurred more commonly in indigenous women and neonates. Isolation of NTHi from any obstetric or neonatal specimen is associated with chorioamnionitis, preterm birth, pregnancy loss, early-onset neonatal sepsis and neonatal death.

Keywords: Haemophilus influenzae; chorioamnionitis; indigenous population; preterm birth; sepsis.