NIAID scanning electron microscope image of Group A Streptococcus (red) interacting with a human neutrophil (orange).
NIAID investigators and colleagues studying group A streptococcus bacteria have identified gene changes in bacterial toxins that they believe make the pathogen more virulent and capable of causing epidemics. A portion of the study, done at NIAID’s Rocky Mountain Laboratories, involved testing the ability of streptococcal strains to interact with cells of the human immune system. The success of the epidemic strains appears linked to their ability to resist killing by human neutrophils. The group, including scientists at facilities in Montana, Texas, Finland and Iceland, next plans to investigate whether a similar process yields epidemic strains of other bacterial agents, such as Staphylococcus aureus, Klebsiella pneumoniae or Escherichia coli.