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| ==Interaction with ''Haemophilus influenzae''==
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| Both ''[[Haemophilus influenzae|H. influenzae]]'' and ''S. pneumoniae'' can be found in the human upper respiratory system. A study of competition in a laboratory revealed that, in a petrì dish, ''S. pneumoniae'' always overpowered ''H. influenzae'' by attacking it with a [[hydrogen peroxide]] and stripping off surface molecules that ''H. influenzae'' needs for survival.
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| When both bacteria are placed together into a nasal cavity, within 2 weeks, only ''H. influenzae'' survives. When both are placed separately into a nasal cavity, each one survives. Upon examining the upper respiratory tissue from mice exposed to both bacteria, an extraordinarily large number of [[neutrophils]] immune cells were found. In mice exposed to only one bacteria, the cells were not present
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| Lab tests show that neutrophils that were exposed to already dead ''H. influenzae'' were more aggressive in attacking ''S. pneumoniae'' than unexposed neutrophils. Exposure to killed ''H. influenzae'' had no effect on live ''H. influenzae''.
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| Two scenarios may be responsible for this response:
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| # When ''H. influenzae'' is attacked by ''S. pneumoniae'', it signals the immune system to attack the ''S. pneumoniae''
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| # The combination of the two species together sets off an immune system alarm that is not set off by either species individually.
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| It is unclear why ''H. influenzae'' is not affected by the immune system response.<ref name="PLosPathog2006-Lysenko">{{cite journal | author=Lysenko ES, Ratner AJ, Nelson AL, Weiser JN | title=The role of innate immune responses in the outcome of interspecies competition for colonization of mucosal surfaces | journal=PLoS Pathog | year=2005 | pages=e1 | volume=1 | issue=1 | id=PMID 16201010}} [http://pathogens.plosjournals.org/perlserv/?request=get-document&doi=#10.1371/journal.ppat.0010001 Full text]</ref>
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| ==References== | | ==References== |
Revision as of 05:53, 9 August 2015