Quantitative comparison and analysis of species-specific wound biofilm virulence using an in vivo, rabbit-ear model.
BACKGROUND
Although bacterial biofilm is recognized as an important contributor to chronic wound pathogenesis, differences in biofilm virulence between species have never been studied in vivo.


METHODS
Dermal punch wounds in New Zealand white rabbit ears were inoculated with Klebsiella pneumoniae, Staphylococcus aureus, or Pseudomonas aeruginosa, or left uninfected as controls. In vivo biofilm was established and maintained using procedures from our previously published wound biofilm model. Virulence was assessed by measurement of histologic wound healing and host inflammatory mediators. Scanning electron microscopy (SEM) and bacterial counts verified biofilm viability. Extracellular polymeric substance (EPS)-deficient P aeruginosa was used for comparison.


RESULTS
SEM confirmed the presence of wound biofilm for each species. P aeruginosa biofilm-infected wounds showed significantly more healing impairment than uninfected, K pneumoniae, and S aureus (p < 0.05), while also triggering the largest host inflammatory response (p < 0.05). Extracellular polymeric substance-deficient P aeruginosa demonstrated a reduced impact on the same quantitative endpoints relative to its wild-type strain (p < 0.05).


CONCLUSIONS
Our novel analysis demonstrates that individual bacterial species possess distinct levels of biofilm virulence. Biofilm EPS may represent an integral part of their distinct pathogenicity. Rigorous examination of species-dependent differences in biofilm virulence is critical to developing specific therapeutics, while lending insight to the interactions within clinically relevant, polybacterial biofilms.
Division of Plastic Surgery, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
Akhil K
AK
Seth
Matthew R
MR
Geringer
Robert D
RD
Galiano
Kai P
KP
Leung
Thomas A
TA
Mustoe
Seok J
SJ
Hong
D000818:Animals; D058491:Bacterial Load; D018441:Biofilms; D015415:Biomarkers / Q000378:metabolism; D004431:Ear, External / Q000293:injuries* / Q000382:microbiology / Q000473:pathology / Q000502:physiology; D018836:Inflammation Mediators / Q000378:metabolism; D007711:Klebsiella pneumoniae / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D008855:Microscopy, Electron, Scanning; D023421:Models, Animal; D011135:Polysaccharides, Bacterial / Q000502:physiology; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D012329:RNA, Bacterial; D012333:RNA, Messenger; D011817:Rabbits; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017695:Soft Tissue Injuries / Q000382:microbiology / Q000473:pathology / Q000503:physiopathology; D013211:Staphylococcus aureus / Q000235:genetics / Q000472:pathogenicity* / Q000502:physiology; D014774:Virulence; D014945:Wound Healing
D015415:Biomarkers; D018836:Inflammation Mediators; D011135:Polysaccharides, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; C064841:exopolysaccharide, Pseudomonas