Abundance in Breastfed Infants and Identification of a New Species in the Global Enterics Multicenter Study.

is a leading cause of bacterial diarrhea worldwide and is associated with high rates of mortality and growth stunting in children inhabiting low- to middle-resource countries. To better understand the impact of breastfeeding on infection in infants in sub-Saharan Africa and South Asia, we examined fecal microbial compositions, bacterial isolates, and their carbohydrate metabolic pathways in -positive infants <1 year of age from the Global Enterics Multicenter Study. Exclusively breastfed infants with diarrhea exhibited high abundances, and this negatively correlated with bacterial carbohydrate metabolism. Although and are prevalent among these infants, the second most abundant species was a new species, which we named " Campylobacter infans." Asymptomatic carriers also possess significantly different proportions of specific gut microbes compared to diarrheal cases. These findings provide insight into infections in infants in sub-Saharan Africa and South Asia and help inform strategies aimed at eliminating campylobacteriosis in these areas. is the primary cause of bacterial diarrhea in the United States and can lead to the development of the postinfectious autoimmune neuropathy known as Guillain-Barré syndrome. Also, drug-resistant campylobacters are becoming a serious concern both locally and abroad. In low- and middle-income countries (LMICs), infection with is linked to high rates of morbidity, growth stunting, and mortality in children, and breastfeeding is important for infant nutrition, development, and protection against infectious diseases. In this study, we examined the relationship between breastfeeding and infection and demonstrate the increased selection for and strains unable to metabolize fucose. We also identify a new species coinfecting these infants with a high prevalence in five of the seven countries in sub-Saharan Africa and South Asia examined. These findings indicate that more detailed studies are needed in LMICs to understand the infection process in order to devise a strategy for eliminating this pathogenic microbe.