Antibiotic selections for which resistance was observed.

The percent of libraries from infants (N = 8) and children and adolescents (N = 12) generating colonies resistant to 14 antibiotics is plotted. Two libraries that were <0.1 GB in size were excluded, as they did not have enough genetic diversity to accurately represent the resistance in their source metagenome. Not shown are four antibiotics for which no resistance was found: ciprofloxacin, meropenem, colistin, and cefepime.