Cytolethal distending toxin (cdt), cytotoxic necrotizing factor (cnf), and cycle inhibiting factor (cif) genes known to cause megalocytosis were not present in either of these genomes, which substantiated our PCR results, suggesting the megalocytic cytotoxicity observed in our in vitro infection experiments was the result of colibactin activity. Here, NPHS1 is linked to infection.