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| Streptococcus (green) and Staphylococcus (red) together in biofilm. By: Reddinger et al, 2018, mBio |
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.
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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, <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
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