Wound-colonizing microorganisms can form complex and dynamic polymicrobial 
communities where pathogens and commensals may co-exist, cooperate or compete 
with each other. The present study was aimed at identifying possible 
interactions between different bacteria isolated from the same chronic wound of 
a patient with the genetic blistering disease epidermolysis bullosa (EB). 
Specifically, this involved two different isolates of the human pathogen 
Staphylococcus aureus, and isolates of Bacillus thuringiensis and Klebsiella 
oxytoca. Particular focus was attributed to interactions of S. aureus with the 
two other species, because of the high staphylococcal prevalence among chronic 
wounds. Intriguingly, upon co-cultivation, none of the wound isolates inhibited 
each other's growth. Since the extracellular proteome of bacterial pathogens is 
a reservoir of virulence factors, the exoproteomes of the staphylococcal 
isolates in monoculture and co-culture with B. thuringiensis and K. oxytoca were 
characterized by Mass Spectrometry to explore the inherent relationships between 
these co-exisiting bacteria. This revealed a massive reduction in the number of 
staphylococcal exoproteins upon co-culturing with K. oxytoca or B. 
thuringiensis. Interestingly, this decrease was particularly evident for 
extracellular proteins with a predicted cytoplasmic localization, which were 
recently implicated in staphylococcal virulence and epidemiology. Furthermore, 
our exoproteome analysis uncovered potential cooperativity between the two 
different S. aureus isolates. Altogether, the observed exoproteome variations 
upon co-culturing are indicative of unprecedented adaptive mechanisms that set 
limits to the production of secreted staphylococcal virulence factors.