Severe infections emerge from commensal bacteria by adaptive evolution

• DOI: 10.7554/elife.30637
• Publication Date: 2017-12-19T16:00:30Z
• Authors: Bernadette C Young; Chieh-Hsi Wu; N Claire Gordon; Kevin Cole; James R Price; Elian Liu; Anna E Sheppard; Sanuki Perera; Jane Charlesworth; Tanya Golubchik; Zamin Iqbal; Rory Bowden; Ruth C Massey; John Paul; Derrick W Crook; Timothy E Peto; A Sarah Walker; Martin J Llewelyn; David H Wyllie; Daniel J Wilson
• Keywords: Commensalism; Pathogenesis

Bacteria responsible for the greatest global mortality colonize human microbiota far more frequently than they cause severe infections. Whether mutation and selection among commensal bacteria are associated with infection is unknown. We investigated de novo in 1163 Staphylococcus aureus genomes from 105 infected patients nose colonization. report that 72% of infections emerged nose, infecting nose-colonizing showing parallel adaptive differences. found 2.8-to-3.6-fold enrichments protein-altering variants genes responding to rsp, which regulates surface antigens toxin production; agr, quorum-sensing, production abscess formation; host-derived antimicrobial peptides. Adaptive mutations pathogenesis-associated were 3.1-fold enriched but not bacteria. None these signatures observed healthy carriers nor at species-level, suggesting infection-associated, short-term, within-host pressures. Our results show spontaneous evolution specifically infection, raising new possibilities diagnosis treatment.