Access Type

Open Access Embargo

Date of Award

January 2019

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Physiology

First Advisor

Kevin . Theis

Second Advisor

Robert . Lasley

Abstract

Introduction

Preterm birth is the number one cause of neonatal morbidity and mortality. A causal link has been established between infection and preterm birth. Urinary tract infection is the number one infection in pregnancy. Evaluating the existence of a placental and maternal bladder microbiome is a major scientific and clinical milestone in perinatal medicine.

Methodology and Results

Chapter 2: This is a prospective case control study. 69 placentas were collected in a sterile fashion from six groups of women without infection: Term cesarean not in labor (n=18), term cesarean in labor (n=9), term vaginal (n=21), preterm cesarean not in labor (n=7), preterm cesarean in labor (n=8), preterm vaginal (n=6). Core placental samples underwent cultivation. DNA extraction and 16S rRNA gene sequencing were performed on swabs that were collected from two sites of the placenta at five placental levels: amnion, amnion-chorion space, subchorion, villous tree and basal plate. Results showed lack of evidence for the existence of placental microbiota.

Chapter 3: The existence of placental microbiome depends on coexistence of trophoblasts and bacteria. We evaluated the inflammatory response of the trophoblasts to co-incubation with a pathogenic bacterium Escherichia coli, and two “commensal” bacteria, Lactobacillus crispatus, and Lactobacillus jensenii. All three bacteria led to significant generation of chemokines and inflammatory cytokines compared to control group (incubation without bacteria). These findings support the finding of chapter 1 that the existence of placental microbiome in healthy placentas is not biologically plausible.

Chapter 4: Urinary tract infection is the number one cause of infection in pregnancy and is associated with serious adverse outcomes including preterm birth. This is a prospective case control study of 25 healthy pregnant women > 35 weeks of gestation. We evaluated the existence of maternal bladder microbiota by performing cultivation and 16S rRNA gene sequencing on Foley catheter, clean catch and vaginal samples. Foley catheter samples indicated the existence of a distinct microbiota by cultivation and next generation sequencing, with Ureaplasma, Gardnerella, and Gram positive anaerobic cocci being potential members.

Conclusion

Our studies provide evidence for the sterility of the placenta and the existence of a distinct maternal bladder microbiota.

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