Disrupting the biofilm matrix improves wound healing outcomes

OBJECTIVE

The most unyielding molecular component of biofilm communities is the matrix structure that it can create around the individual microbes that constitute the biofilm. The type of polymeric substances (polymeric sugars, bacterial proteins, bacterial DNA and even co-opted host substances) are dependent on the microbial species present within the biofilm. The extracellular polymeric substances that make up the matrix give the wound biofilm incredible colony defences against host immunity, host healing and wound care treatments. This polymeric slime layer, which is secreted by bacteria, encases the population of microbes, creating a physical barrier that limits the ingress of treatment agents to the bacteria. The aim of this study was to determine if degrading the wound biofilm matrix would improve wound healing outcomes and if so, if there was a synergy between treating agents that disrupted biofilm defenses with Next Science Wound Gel (wound gel) and cidal agents (topical antibiotics).

METHOD

A three-armed randomised controlled trial was designed to determine if standard of care (SOC) was superior to SOC plus wound gel (SOC + gel) and wound gel alone. The wound gel used in this study contains components that directly attack the biofilm extracellular polymeric substance. The gel was applied directly to the wound bed on a Monday-Wednesday-Friday interval, either alone or with SOC topical antibiotics.

RESULTS

Using a surrogate endpoint of 50% reduction in wound volume, the results showed that SOC healed at 53%, wound gel healed at 80%, while SOC plus wound gel showed 93% of wounds being successfully treated.

CONCLUSION

By directly targeting the wound biofilm matrix, wound healing outcomes are improved.

Molecular diagnosis of Raoultella planticola infection of a surgical site

Raoultella planticola has been rarely diagnosed in clinical specimens. A case of a polymicrobial surgical site infection primarily caused by R. planticola in a 66-year-old Caucasian male with a fractured left tibia after an open reduction internal fixation of his left ankle is described and confirms this organism to be an opportunistic human pathogen. This pathogen was diagnosed with rapid clinical molecular pathogen diagnostic methods, which allowed an appropriate therapy to be implemented, thereby improving prognosis.

Effects of biofilm treatments on the multi-species Lubbock chronic wound biofilm model

OBJECTIVE

To evaluate the efficacy of several biofilm effectors in inhibiting biofilm formation in an in vitro multi-species chronic wound biofilm model.

METHOD

The Lubbock Chronic Wound Biofilm (LCWB) model has been described in detail elsewhere. Pathogens used in the model are Pseudomonas aeruginosa, Enterococcus faecalis and Staphylococcus aureus. These are three of the most important species associated with biofilms. Here, the model was exposed to the following biofilm effectors: xylitol, salicylic acid, farnesol, erythritol and two proprietary, semi-solid, wound-dressing formulations currently under development (Sanguitec gels).

RESULTS

Biofilm formation was completely inhibited in the LCWB model following treatment with 20% xylitol, 10% erythritol, 1,000 microg/ml farnesol, 20mM salicylic acid or 0.1% of either of the two Sanguitec gel formulations. Salicylic acid specifically inhibited S. aureus (p<0.01) at 10mM and 20mM, consequently increasing the ratios of P. aeruginosa and E. faecalis within the biofilm. Xylitol had an increasing inhibitory effect on P. aeruginosa (p<0.01) at all concentrations evaluated. Erythritol had an inhibitory effect on P. aeruginosa and S. aureus growth (p<0.01) at over 5% concentrations. The inhibitory effect of both Sanguitec gel formulations was more broadly effective, with an increasingly inhibitory effect on all LCWB species (p<0.01).

CONCLUSION

The LCWB model provides a multi-species format with which to evaluate the effect of biofilm effectors on wound flora in a biofilm phenotype. These results suggest that different treatments can target specific populations within a biofilm. Salicylic acid preferentially targeted S. aureus, xylitol preferentially targeted P. aeruginosa, while erythritol preferentially targeted both P. aeruginosa and S. aureus. In contrast, the two Sanguitec gel formulations provided a broad, less preferential, inhibition of biofilm development.

DECLARATION OF INTEREST

Research and Testing Laboratory is a for-profit enterprise that develops molecular methods and performs service research work on biofilms. Sanguitec gel was developed by JPK and CEJ.

Propagation of anaerobic bacteria within an aerobic multi-species chronic wound biofilm model

OBJECTIVE

Most chronic wound biofilms have been shown to have significant populations of anaerobes. In order to better screen antimicrobial and antibiofilm therapeutics, we evaluated the ability of key anaerobes to incorporate and propagate within our aerobic chronic wound biofilm.

METHOD

We had previously developed a rapid model to simulate polymicrobial chronic wound biofilms. This model incorporated meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus faecalis (VRE) and Pseudomonas aeruginosa. The model was used along with a variety of anaerobes to determine whether this biofilm model would support propagation of anaerobes similar to that we have identified in chronic wounds.

RESULTS

Using our previously defined Lubbock Chronic Wound Biofilm (LCWB) model combined with quantitative PCR, anaerobic bacteria were shown to proliferate through integration into the biofilm under aerobic conditions. Using electron microscopy we show close association between aerobes and anaerobes within the biofilm suggesting a synergistic relationship.

CONCLUSION

We have expanded the utility of the LCBW to show the ability of clinically significant anaerobic bacteria to thrive in aerobic conditions. The expansion of this model can further simulate the functional characteristics of chronic wound pathogenic biofilms and the species that dwell within them allowing improved ability to evaluate therapeutics that target anaerobes.

Behavioral management of conversion disorder in children

OBJECTIVE

To describe the behavioral management of conversion disorder in children and to preliminarily assess its effectiveness.

DESIGN

Retrospective case series.

SETTING

Inpatient pediatric rehabilitation unit.

PATIENTS

The first eight patients with conversion disorder treated on our pediatric rehabilitation unit, between 9 and 18 years of age. Six were girls. Three cases are described in detail.

INTERVENTIONS

All patients were treated as inpatients, using a behavioral approach. Inadvertent reinforcement of illness behavior was identified, and a reward system was established for good attainment. Some patients had a "level" system instituted, with increasing privileges for goal achievement. All patients and their families had psychological assessment and instruction in pain and stress management strategies.

MAIN OUTCOME MEASURES

Restoration of normal gait and function, independence in activities of daily living (ADL), and symptom recurrence after discharge.

RESULTS

All patients attained normal gait and ADL function before discharge.

CONCLUSIONS

(1) Behavioral management of conversion disorder in children appears to be as effective as in adults, although at times a behavioral reward or "level" system may be necessary for adequate reinforcement. (2) Instruction of the patient and family in appropriate stress and pain management appears key to maintaining treatment effect over time.