Bacterial vaginosis (BV) has been considered to be the most prevalent infection found in sexually active women. BV is thought to play an important role in the premature rupture of membranes (PROM) and preterm birth. Preterm delivery accounts for a substantial percentage of low birth weight infants and perinatal mortality and morbidity.
Bacteroides and
Prevotella species have been isolated from the amniochorion of women with preterm birth and PROM. Women with >104 /mL
Prevotella bivius
(formerly
Bacteroides bivius
) have a 60-100% higher rate of preterm delivery. The purpose of this study was to determine wether some strains of
Prevotella species isolated from PROM and BV patients produce proteases especially collagenase enzymes which faciliate the rupture of membranes leading to preterm birth.
Vaginal specimens have been obtained from 120 women with BV and premature rupture of membrane in 30-44 weeks gestational age. Twenty anaerobic coccobacilli consisting of
Bacteroides fragilis
, black pigmented
Bacteroides and
Prevotella bivius were isolated and identified. The isolates were examined for protease activity, using porcine skine gelatin and casein as substrates by Martleys method.
Elastase and collagenase activity were detected using elastin, guinea pig skin collagen, bovine achilles tendon collagen, FALGPA and GP,VPK as substrates by Levenson method.
Collagenase and elastase activity was detected in 90 and 100% of isolates. Gelatinase and caseinase activity was detected in 40 and 50 % of isolates. Collagenase produced by Prevotella bivia isolates was purified by ammonium sulphate precipitation, gel filtration and ion exchange chromatography. The collagenase was cleaved from the synthetic collagen substrate FALGPA, and GP, VPK substrates. The activity of the enzyme was inhibited by EDTA, Antipain and PMSF.
This study suggests that proteases produced by
Prevotella bivia may be involved in the pathogenesis of premature rupture of membrane. PROM before 37 weeks has been reported to be significantly higher among patients with
Bacteroides and
Prevotella colonisation of the genital tract. The amniochorion consists of collagen and elastin which convey physical integrity to the placenta. Collagenase and elastase released into the genital tract may promote connective tissue destruction in the cervix and chorioamnion membranes.
