Becteria-induced Preterm Delivery and the Effects of Antibiotics on its Prognosis in the Rabbit / 대한산부인과학회잡지

ABSTRACT

Bacterial infection has been implicated in premature labor in human. But it is impossible to undergo human study of bacteria-induced preterm delivery. If we carry out animal experiment which simulate human preterm delivery induced by bacteria, studies for mechanism, diagnosis, and treatment of preterm delivery will be progressed rapidly. To elucidate mechanisms and potential intervention strategies in preterm pregnancy loss, we observed bacteria-induced preterm labor and the protecting effect of administration of antibiotics with hysteroscopy-guided intracervical inoculation of Escherichia coli. Sterile saline solution(group I, n=5) or 2x10(7)cfu (colony-forming units) of E. coli bilaterally in the cervix of pregnant New Zealand White rabbits on day 20 or 21(70% of gestation) by hysteroscopy was inoculated and rabbits were assinged to ampicillin-sulbactam therapy beginning at 0hr(group II, n=4), 2 hr(group III, n=4), 4 hr(group IV, n=2), and 16 hr(group V, n=2) after inoculation with E. coli, or to no antibiotic therapy(group VI, n=3). Unasyn(ampicillin-sulbactam) was used and its daily dosage was 100 mg/kg/day. The occurrence of vaginal bleeding or preterm birth was observed every two hours. If one rabbit fetus was found to be delivered, exploratory laparotomy was done. Amniotic fluid culture on each sac, decidual culture on each uterine cavity, and pathologic examinations on each placenta were done. The results of experiments are as follows. In control group(0.2cc sterile saline inoculation only), there was no preterm labor and no bacterial growth in culture. In all three rabbits in group VI, preterm delivery occurred and the culture results were all positive in maternal blood, decidua, and amniotic sacs. Preterm delivery also occurred in group V, but results of maternal blood culture were all negative. Increased trend in the occurrence of preterm delivery was statistically significant in the order(p < 0.05) group I(0/5), group II(0/4), group III(0/4), group IV(0/2), group V(2/2), and group VI(3/3). Pregnancy outcomes on the basis of the number of living fetus, dead fetus, and macerated fetus, have significant trend in the above order. Amniotic fluid culture results also had significant relationship(p < 0.05) group I(0.20), group II(20/26), group III(18/30), group IV(10/11), and group VI(7/7). In group V, amniotic fluid fail to be obtained due to severe oligohydramnios. Decidual culture results also had an increased trend; group I(0/32), group II(21/29), group III(20/30), gorup IV(16/16), gorup V(11/11), and group VI(25/25). It is statistically significant(p < 0.05) Incidence of histologic chorioamnionitis was also significantly increased from group I to VI. These results indicate that E. coli inoculation has induced preterm delivery and antibiotic therapy has somewhat prevented preterm birth, amniotic fluid infection, decidual infection, and histologic chorioamnionits. Antibiotic effects were attenuated in cases of delayed antibiotic administration.