BF V3 275

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Sunday, 26 August 2018 21:42

Pathogen Prevents Pathogen Pervasion - BacterioFiles 353

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Published in Bacteriofiles

This episode: Some bacteria that can cause pneumonia can prevent other bacteria from doing the same!

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(9.6 MB, 10.5 minutes)

Show notes: 

bf353staphstrepMicrobe of the episode: Bell pepper mottle virus

Journal Paper:
Reddinger RM, Luke-Marshall NR, Sauberan SL, Hakansson AP, Campagnari AA. 2018. Streptococcus pneumoniae Modulates Staphylococcus aureus Biofilm Dispersion and the Transition from Colonization to Invasive Disease. mBio 9:e02089-17.

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Episode outline:

  • Background: Body has many natural defenses
    • Physical barriers like skin
    • Chemical barriers like antimicrobials
    • Plus immune system
  • Also barriers erected through technology, like clean water and other sanitization
    • Vaccines to boost natural defenses
  • Still pathogens can break through, cause disease
    • And if multiple attack via different paths, can be even worse
  • Influenza infection can weaken defenses, allow other pathogens to cause severe pneumonia
    • Streptococcus pneumoniae, aka pneumococcus, makes biofilms in most people
      • But can infect resp tract, lungs, ears, esp of young and old
      • Vaccine available, targets polysaccharide capsule, but >90 types, hard to target all
      • Targeting some, 13 or 23, but can allow others to take their place
    • Also Staphylococcus aureus, also normally colonizes nose of ~1/3 to 3/4 of people
      • Can cause very severe pneumonia after flu
  • But when pathogen approaches are too similar, they come to compete with each other
    • Try to inhibit rather than working together
  • What’s new: Now, scientists publishing in mBio have discovered that pneumococcus can sometimes prevent Staph aureus from causing disease!
  • Methods: Previously showed each species can form biofilms in cell cultures
    • H292, human lung epithelial cell line, derived from tumor
  • But what about together?
    • Found they could make stable biofilms together for at least 48h
    • Strep makes flat mat-like film, Staph builds up towers on it
  • Disease results when they disperse from biofilm
    • Induced like when influenza infection causes fever
    • So tried heating stable biofilm setups to see response
      • Each individual species alone dispersed more with heat
      • But together, Strep dispersed more but Staph dispersed less
    • Seems like Strep is changing Staph's behavior
    • Doesn't happen with Streptococcus mitis, species that also forms biofilms
  • Then tried in mice, colonizing nasal passages
    • Both species together set up stable biofilm
    • Stayed there, didn't spread and cause disease
  • Then tried shocking system with influenza infection
    • >60% of mice had pneumococcal pneumonia,
    • None had both species in lungs
    • So even in vivo Strep seems to keep Staph in place
  • Summary: Streptococcus pathogens can grow together in a biofilm with Staphylococcus pathogens in nasal passages, but Streptococcus seems to keep Staphylococcus from leaving the biofilm and causing disease
  • Applications and implications: Maybe helpful for diagnosis/treatment
    • 2nd infection pneumonia after flu often very serious
    • Don't have to look for Staph as much if Strep present
  • Also good reminder that microbiota are complex
    • disrupting some aspect like with vaccine can have unintended consequences
    • Pay more attention to effects from vaccine in future, see if Staph risk higher
  • Try to figure out how Strep prevents Staph from leaving biofilm
    • Good preventive treatment, probably wouldn't have as much risk of resistance
  • What do I think: More pathogens not always worse, if competitive
    • Best to have competitive friendly microbe keeping away pathogens
    • Like Staph epidermidis vs. Strep as discussed last episode
    • But take what we can get
  • Enemy of our enemy is not always a friend
Last modified on Sunday, 26 August 2018 21:47
Jesse Noar

Jesse Noar is microbiologist with a PhD from North Carolina State University and Bachelor's from Cornell. Most of his research has focused on the amazing abilities and potential uses of bacteria, especially those found in soil. Jesse hosts the BacterioFiles podcast highlighting the most interesting recent microbiology research on all kinds of different microbes, part of the ASM family of podcasts. Learn more at or at