Fig. 1

Twin infant fecal resistomes resemble those of their siblings. Predicted resistance proteins were collapsed into 97 % identity clusters. Binary Jaccard resistance protein cluster composition similarity was determined for (1) the same infant at different timepoints (self-sharing), (2) twin siblings, (3) unrelated infants, and (4) mothers and infants from the same family. a All resistance proteins at left; b the subset of β-lactamases and penicillin-binding proteins at right. Significance was calculated using the Student’s t-test with 1000 Monte Carlo simulations (**p < 0.01). Infant resistomes overall (a) were significantly more similar to a twin sibling or to the same subject at different timepoints than to their mothers or unrelated infants. Infant resistomes were no more similar to those of their mothers than to unrelated infants. There was also no significant difference between the similarity between infants and their twin sibling and the persistence of resistance proteins within a given individual at different timepoints (self-sharing)