Strengths and Limitations
Our study has some limitations. First, since we analyzed the relationship between the results of vaginal culture at admission and neonatal outcomes, our analysis did not consider antibiotic treatment during hospitalization, which may affect the neonatal outcomes. Second, although cerclage was identified as a risk factor for ESBL-E vaginal colonization, the causality is uncertain. In fact, a previous study has demonstrated that the proportion of Lactobacillus spp. was reduced, while that of abnormal vaginal flora increased before rescue cerclage.28 Considering this result, the possibility that ESBL-E vaginal colonization had already occurred before the operation could not be excluded because information on vaginal culture before cerclage was not available in this study population.
To the best of our knowledge, this is the first study to identify changes in the prevalence and risk factors of ESBL-E vaginal colonization in high-risk pregnancies. Our study is also meaningful in that we included a relatively large number of patients who underwent vaginal culture according to the protocol of our institution. In addition, the need for further studies on the treatment of ESBL-E colonization and pregnancy outcomes was identified in this study. For example, there are only a few randomized controlled trials on ESBL-E infection treatment, and there are many controversies on whether antibiotic treatment for ESBL-E infection is effective or on which treatment methods are effective.45,46