Metagenomic survey of pathogen prevalence in the infant gut

The human microbiota impacts our health and well-being from infancy throughout our lives. Besides mutualistic and commensal strains, it also contains opportunistic pathogens. Infants may be especially vulnerable to opportunistic pathogen colonisation due to their immature immune systems and low microbial diversity.The study aims to examine associations between opportunistic pathogen prevalence and factors such as breastfeeding, antibiotic use, birth-mode, and the presence of other bacterial taxa. This study analysed 3981 publicly available shotgun metagenomes collected from 1275 infants and 415 mothers across ten countries to identify species that may be considered opportunistic pathogens in the infant gut. The prevalence of C. difficile was decreased in breastfed infants and in those carrying Faecalibacterium and Dorea spp. S. aureus carriage was negatively associated with antibiotic use and positively with skin contact and breastfeeding. K. pneumoniae was acquired later in life and was more prevalent in premature infants, and less commonplace in vaginal deliveries without antibiotics. Our findings indicate that opportunistic pathogen prevalence in the infant gut is influenced by medical and caregiving practices and may be modifiable through targeted interventions. Reducing the spread of these opportunistic pathogens could contribute to global efforts against early life infections.