Haemophilus influenzae Intra-Amniotic Infection With Intact Membranes

Abstract

Background: Amnionitis rarely occurs with intact membranes. Haemophilus influenzae is a rare pathogen in intra-amniotic infection, but its importance and prevalence could be increasing, as reflected by the growing number of reported cases in the last 20 years.

Methods: Using the key words “amnionitis,” “intra-amniotic infection,” “chorioamnionitis,” and “Haemophilus influenzae,” we searched MEDLINE files from 1980 to the present. Articles dating before 1980 were accessed from cross-reference of the more recent studies.

Results and Conclusions: H. influenzae, a nonmotile, aerobic, gram-negative rod-shaped bacteria, is primarily responsible for respiratory tract infections in children and neonatal meningitis; it has a low prevalence rate in genital tract cultures but a high attack rate of infection in mothers and neonates. With intact membranes, intra-amniotic infection occurs rarely and is thought to be caused by hematogenous transplacental seeding, direct invasion of the fetal membranes, or inoculation of the amniotic fluid during an invasive procedure. It can also be idiopathic.

It occurs most often in the second and early third trimesters and can be definitively diagnosed by a positive amniotic fluid culture or positive maternal or neonatal blood cultures and clinical evidence of intra-amniotic infection. We present a case of intra-amniotic infection with intact membranes at 15 to 16 weeks in a patient with clinical evidence of intra-amniotic infection and positive blood cultures whose infection was treated successfully with antibiotics, prolonging her pregnancy by 16 weeks.

Physicians caring for obstetric patients must be vigilant in diagnosing intra-amniotic infection, even with intact membranes, and this infection should be considered in the differential diagnoses for acute abdomen in pregnancy.