Microbiological features and perinatal outcomes in patients with preterm premature rupture of membranes and oligohydramnios

BACKGROUND: Oligohydramnios in preterm premature rupture of membranes is the cause of increased perinatal morbidity and mortality among preterm newborns. Microbiological features in women with preterm premature rupture of membranes and oligohydramnios are probably some of the determining factors affecting the implementation of an unfavorable outcome of gestation.

AIM: The aim of this study was to determine microbiological features and perinatal outcomes in patients with preterm premature rupture of membranes and oligohydramnios.

MATERIALS AND METHODS: This retrospective study conducted from 2018 to 2021 included 161 pregnant women with PPROM at 24 to 33 weeks and 6 days of gestation. Of these, the main group consisted of 83 patients with signs of oligohydramnios, while the control group comprised 78 patients without oligohydramnios. Patient examination upon admission to the hospital included analysis of the amniotic fluid index, the white blood cell differential, plasma ferritin and C-reactive protein levels, and bacteriological tests of vaginal secretions by isolating and growing microbes on optimal culture media.

RESULTS: The patients with oligohydramnios had shorter latent period (р = 0.004), but the noted distinctions were a higher frequency of clinical chorioamnionitis (р = 0.025), fetal distress (р = 0.030), and earlier parturition (р = 0.040) with more frequent caesarean sections (р = 0.016) compared to the control group. Vaginal microbiota in the main group showed a higher prevalence of Staphylococcus aureus (р = 0.008), Bacteroides spp. (р = 0.030), Streptococcus spp. (р = 0.002), Micrococcus spp. (p < 0.001), Bacillus subtilis (p < 0.001), Bacillus megaterium (p = 0.009), Bacillus buchneri (р = 0.008), Klebsiella pneumoniae (р = 0.002), Haemophilus spp. (р = 0.005) and no Candida albicans compared to the control group. In the main group, newborns more often had a lower body weight at birth (р = 0.002) and a lower Apgar score at the fifth minute (р = 0.011). They also showed higher incidences of respiratory distress syndrome (р = 0.006), bronchopulmonary dysplasia (р = 0.036), congenital pneumonia (р = 0.011) and necrotizing enterocolitis (р = 0.022) and more often needed treatment in an intensive care unit (р = 0.034), including surfactant supplementation (р = 0.007), cardiotonic support (р = 0.004) and artificial lung ventilation (р = 0.006) compared to the control group.

CONCLUSIONS: Oligohydramnios in preterm premature rupture of membranes is associated with pronounced dysbiotic changes in the vaginal microbiota including the prevalence of Micrococcus spp., Streptococcus spp., Staphylococcus aureus and absence of Candida spp. from the isolates, as well as increased incidence of adverse perinatal outcomes.