Monday, August 27, 2018

BacterioFiles 353 - Pathogen Prevents Pathogen Pervasion

Streptococcus (green) and
Staphylococcus (red)
together in biofilm.
By: Reddinger et al, 2018, mBio
This episode: Some bacteria that can cause pneumonia can prevent other bacteria from doing the same!

Download Episode (9.6 MB, 10.5 minutes)

Show notes:
Microbe 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.

Other interesting stories:

Post questions or comments here or email to Thanks for listening!

Subscribe: Apple Podcasts, RSS, Google Play. Support the show at Patreon, or check out the show at Twitter or Facebook.

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, <15 had="" li="" rest="" sick="" staph="" t="" weren="">
    • 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

No comments:

Post a Comment