Nasal carriage as a source of agr-defective staphylococcus aureus bacteremia

Davida S. Smyth, Jared M. Kafer, Gregory A. Wasserman, Lili Velickovic, Barun Mathema, Robert S. Holzman, Tiffany A. Knipe, Karsten Becker, Christof Von Eiff, Georg Peters, Liang Chen, Barry N. Kreiswirth, Richard P. Novick, Bo Shopsin

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Inactivating mutations in the Staphylococcus aureus virulence regulator agr are associated with worse outcomes in bacteremic patients. However, whether agr dysfunction is primarily a cause or a consequence of early bacteremia is unknown. Analysis of 158 paired S. aureus clones from blood and nasal carriage sites in individual patients revealed that recovery of an agr-defective mutant from blood was usually predicted by the agr functionality of carriage isolates. Many agr-positive blood isolates produced low levels of hemolytic toxins, but levels were similar to those of colonizing strains within patients, suggesting that introduction into the blood did not select for mutations with minor functional effects. Evidently, the transition from commensalism to opportunism in S. aureus does not require full virulence in hospitalized patients. Furthermore, agr-defective mutants were found in uninfected nasal carriers in the same proportion as in carriers who develop bacteremia, suggesting low correlation between virulence and infectivity.

Original languageEnglish (US)
Pages (from-to)1168-1177
Number of pages10
JournalJournal of Infectious Diseases
Issue number8
StatePublished - Oct 15 2012

All Science Journal Classification (ASJC) codes

  • Infectious Diseases
  • Immunology and Allergy

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    Smyth, D. S., Kafer, J. M., Wasserman, G. A., Velickovic, L., Mathema, B., Holzman, R. S., Knipe, T. A., Becker, K., Von Eiff, C., Peters, G., Chen, L., Kreiswirth, B. N., Novick, R. P., & Shopsin, B. (2012). Nasal carriage as a source of agr-defective staphylococcus aureus bacteremia. Journal of Infectious Diseases, 206(8), 1168-1177.