Abstract
Biofilms are aggregates of bacteria encased in an extracellular polymer matrix that acts as a diffusion barrier protecting the microbial community. Bacterial communication occurs by small signaling molecules called quorum sensing (QS) factors, which are involved in the activation of virulence genes and formation of biofilms. Larvae of the green bottle blowfly Lucilia sericata remove necrotic tissue by mechanical action (debridement) and proteolytic digestion. We produced a freeze-dried storable powder from larval extract and investigated its therapeutic effect on biofilms. Larval extract in concentrations of 6 and 12 mg/mL in combination with 0.5% antibiotics (≙50 U/mL penicillin and 50 μg/mL streptomycin) diminished free-floating (planktonic) Pseudomonas aeruginosa maintenance, while it showed no effect on Staphylococcus aureus and was not toxic to dermal cells. We established an ex vivo human dermal wound model. Larval extract in concentrations of 24 and 75 mg/mL in the presence of antibiotics (0.5%) significantly destroyed the biofilm stability of both P. aeruginosa and S. aureus biofilms. Furthermore, SEM analyses revealed crack and gap formations on P. aeruginosa. biofilm surface and decreased expression of P. aeruginosa biofilm maturation and virulence genes (lasR, rhlR and rhlA) was observed after treatment by larval extract in combination with antibiotics.
Highlights
IntroductionBacterial biofilms are complex structures consisting of microbial communities encased in extracellular polymer matrix containing polysaccharides, proteins, and nucleic acids [1,2]
Introduction iationsBacterial biofilms are complex structures consisting of microbial communities encased in extracellular polymer matrix containing polysaccharides, proteins, and nucleic acids [1,2]. antibiotics still show great therapeutic effects on individual, free-floating bacteria, their effect on biofilms is inherently negligible [3]
To analyze the effect of Larveel® on cells infected with Gram-negative and Grampositive bacteria, fibroblast and keratinocyte co-cultures were infected with P. aeruginosa or
Summary
Bacterial biofilms are complex structures consisting of microbial communities encased in extracellular polymer matrix containing polysaccharides, proteins, and nucleic acids [1,2]. Antibiotics still show great therapeutic effects on individual, free-floating (planktonic) bacteria, their effect on biofilms is inherently negligible [3]. Even the long-term use of antibiotics in high concentrations does not guarantee the elimination of microorganisms within biofilms [6]. A further mechanism is that extracellular matrix protects chronic wound biofilms from the inflammatory processes of the host, which plays a significant role in wound healing [7,8]. Mature biofilms can persist in humans for many months or even over the lifetime of the host [9].
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