Listeria monocytogenes infection in pregnancy macaques alters the maternal gut microbiome

ObjectivesThe bacterium Listeria monocytogenes (Lm) is associated with adverse pregnancy outcomes. Infection occurs through consumption of contaminated food that is disseminated to the maternal-fetal interface. The influence on the gastrointestinal microbiome during Lm infection remains unexplored in pregnancy. The objective of this study was to determine the impact of listeriosis on the gut microbiota of pregnant macaques. MethodsA nonhuman primate model of listeriosis in pregnancy has been previously described [1, 2]. Both pregnant and nonpregnant cynomolgus macaques were inoculated with L. monocytogenes and bacteremia and fecal shedding were monitored for 14 days. Nonpregnant animal tissues were collected at necropsy to determine bacterial burden, and fecal samples from both pregnant and nonpregnant animals were evaluated by 16S rRNA next-generation sequencing. ResultsUnlike pregnant macaques, nonpregnant macaques did not exhibit bacteremia, fecal shedding, or tissue colonization by Lm. Dispersion of Lm during pregnancy was associated with a significant decrease in alpha-diversity of the host gut microbiome, compared to nonpregnant counterparts. The combined effects of pregnancy and listeriosis were associated with a significant loss in microbial richness, although there were increases in some genera and decreases in others. ConclusionsAlthough pregnancy alone is not associated with gut microbiome disruption, we observed dysbiosis with listeriosis during pregnancy. The macaque model may provide an understanding of the roles that pregnancy and the gut microbiota play in the ability of Lm to establish intestinal infection and disseminate throughout the host, thereby contributing to adverse pregnancy outcomes and risk to the developing fetus. Summary sentenceIntestinal microbial composition in macaques is influenced by significant interaction between the pregnant state and exposure to Listeria monocytogenes, associated in particular with significant changes to Akkermansia, Eubacteria ruminantum, Methanobrevibacter, Prevotella, and Treponema.