606: Stability of the maternal urinary microbiome across pregnancy

Abstract

To assess for longitudinal variation in the maternal urinary microbiome from the 1st trimester (1T) to the 2nd trimester (2T) of pregnancy. This is a prospective IRB-approved cohort study of 29 pregnant women with a singleton pregnancy < 14 weeks. Consented subjects provided a clean catch urine sample during their 1T and again in the 2T. Exclusion criteria included recurrent UTI, antibiotic use since conception, and urinary tract anomalies. Both samples were assessed by 16S rRNA gene sequencing. Using genus-level classification, from a single replica, alpha-diversity was measured, the Bray–Curtis distance calculated, and the complete method used for hierarchical clustering in RStudio. The clusters, termed urotypes, were named for the predominant microbe. Species-level identification was used to calculate the Bray-Curtis dissimilarity index (BC). A BC value of 0.5 was used to sort paired 1T and 2T urine samples as similar (< 0.5) or different (≥0.5). For descriptive purposes, samples were hierarchically clustered with complete-linkage agglomeration by the 1T urine results. A total of 29 patients were assessed in the first trimester. Thirteen patients provided a 2T urine, including 1 patient who was diagnosed with asymptomatic bacteriuria and was subsequently treated with antibiotics. The majority were multiparous (n=9) with a mean age of 29.5 years. 16S rRNA gene sequencing detected live microbes in 1T and 2T urine samples for all subjects. (Figure 1). 1T and 2T urine samples clustered into 3 and 4 urotypes, respectively, with the Lactobacillus urotype most common. Based on BC indices (Figure 2), paired 1T and 2T samples were similar (BC< 0.5) for 92% (n=12) of subjects Of the 11 subjects with a 1T Lactobacillus urotype, 8 had a 2T Lactobacillus urotype, including the patient who was diagnosed with asymptomatic bacteriuria and treated with antibiotics. The clean catch urine microbiome of pregnant women in their 1st trimester is similar to the 2nd trimester. Lactobacillus was the dominant organism at both time points for the vast majority of women.View Large Image Figure ViewerDownload Hi-res image Download (PPT)