Infectious dose dictates the host response during Staphylococcus aureus orthopedic-implant biofilm infection

Debbie Vidlak, Tammy Kielian

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


Staphylococcus aureus is a leading cause of prosthetic joint infections (PJIs) that are typified by biofilm formation. Given the diversity of S. aureus strains and their propensity to cause community- or hospital-acquired infections, we investigated whether the immune response and biofilm growth during PJI were conserved among distinct S. aureus clinical isolates. Three S. aureus strains representing USA200 (UAMS-1), USA300 (LAC), and USA400 (MW2) lineages were equally effective at biofilm formation in a mouse model of PJI and elicited similar leukocyte infiltrates and cytokine/chemokine profiles. Another factor that may influence the course of PJI is infectious dose. In particular, higher bacterial inocula could accelerate biofilm formation and alter the immune response, making it difficult to discern underlying pathophysiological mechanisms. To address this issue, we compared the effects of two bacterial doses (103 or 105 CFU) on inflammatory responses in interleukin-12p40 (IL-12p40) knockout mice that were previously shown to have reduced myeloid-derived suppressor cell recruitment concomitant with bacterial clearance after low-dose challenge (103 CFU). Increasing the infectious dose of LAC to 105 CFU negated these differences in IL-12p40 knockout animals, demonstrating the importance of bacterial inoculum on infection outcome. Collectively, these observations highlight the importance of considering infectious dose when assessing immune responsiveness, whereas biofilm formation during PJI is conserved among clinical isolates commonly used in mouse S. aureus infection models.

Original languageEnglish (US)
Pages (from-to)1957-1965
Number of pages9
JournalInfection and immunity
Issue number7
StatePublished - 2016

ASJC Scopus subject areas

  • Parasitology
  • Microbiology
  • Immunology
  • Infectious Diseases


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