Maggot therapy for resistant infections: the disconnect between scientific evidence, clinical acceptance and practice.

OBJECTIVE: Practitioners and scientists are re-examining marginalised wound care therapies to find strategies that combat the growing problem of antimicrobial resistance (AMR) without compromising patient outcomes. Maggot therapy (MT) makes up just an estimated 0.02% of UK's National Health Service spending on wound care. This study aims to uncover why MT is not used more often, despite its affordability and high level of efficacy for both debridement and disinfection, particularly in the context of AMR infections, and to determine what can be done to ensure MT is more effectively used in the future to improve patient outcomes and manage the growing problem of AMR. METHOD: For this investigation, a qualitative review of case studies using MT against AMR infections and a quantitative analysis of randomised control trials (RCTs) were performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses framework. RESULTS: Analysis showed that MT is highly effective against a range of infections and wound types, and compares well against conventional therapies. The low use of MT may be due in part to the documented 'yuck factor', often associated with maggots as well as misconceptions around the cost, efficacy and accessibility of MT. To overcome these factors, more RCTs on the spectrum and efficacy of MT across various clinical manifestations are needed, as well as professional and public engagement campaigns. CONCLUSION: MT is an underused therapy, particularly regarding AMR infections, and expanding its use in these circumstances appears warranted. MT could play a vital role in conserving the efficacy of the existing pool of antimicrobials available and should be considered in the development of antimicrobial stewardship programmes. DECLARATION OF INTEREST: This work was supported by the Swansea Employability Academy, Swansea University (internal funding). The authors have no conflicts of interest to declare.

Larval Therapy and Larval Excretions/Secretions: A Potential Treatment for Biofilm in Chronic Wounds? A Systematic Review.

Chronic wounds present a global healthcare challenge and are increasing in prevalence, with bacterial biofilms being the primary roadblock to healing in most cases. A systematic review of the to-date knowledge on larval therapy's interaction with chronic-wound biofilm is presented here. The findings detail how larval therapy-the controlled application of necrophagous blowfly larvae-acts on biofilms produced by chronic-wound-relevant bacteria through their principle pharmacological mode of action: the secretion and excretion of biologically active substances into the wound bed. A total of 12 inclusion-criteria-meeting publications were identified following the application of a PRISMA-guided methodology for a systematic review. The findings of these publications were qualitatively analyzed to provide a summary of the prevailing understanding of larval therapy's effects on bacterial biofilm. A further review assessed the quality of the existing evidence to identify knowledge gaps and suggest ways these may be bridged. In summary, larval therapy has a seemingly unarguable ability to inhibit and degrade bacterial biofilms associated with impaired wound healing. However, further research is needed to clarify and standardize the methodological approach in this area of investigation. Such research may lead to the clinical application of larval therapy or derivative treatments for the management of chronic-wound biofilms and improve patient healing outcomes at a time when alternative therapies are desperately needed.

Evaluating nursing opinion and perception of maggot therapy for hard-to-heal wound management.

OBJECTIVE: Maggot therapy (MT) or larval debridement therapy is a recognised, effective but underutilised treatment for the management of hard-to-heal wounds and infected ulcers. It is available on NHS prescription in the UK, where wound management is predominantly nurse-led. Anecdotal reports and published literature suggest that nurses may be reluctant to utilise the therapy. The aim of this study was to evaluate the feelings and opinions of nurses regarding the use of MT. METHOD: The first stage of this mixed-methods study was a focus group held to discuss MT and opinions of specialist nurse clinicians. Next, an anonymised web-based online survey was launched through the Nursing Times journal and distributed through social media targeting all nurses. Finally, in-depth interviews were held with specialist and generalist nurses. RESULTS: Awareness of MT among all nurses was extremely high. A breakdown of results showed that MT was much more highly regarded by wound specialist nurses than non-wound specialist nurses. The latter exhibited a greater level of reluctance to administer the therapy, with almost one-third of these nurses surveyed saying they found maggots disgusting and that the idea of MT made their skin crawl. In-depth interviews revealed that a lack of knowledge about MT was a prime concern. CONCLUSION: Wound specialist nurses are more likely to embrace MT than non-wound nurse specialists, who report a varying degree of wariness to MT. Our study highlights a need for better education and training in MT for all nurses, to address issues with acceptance and willingness to treat or help treat patients with hard-to-heal wounds which are suitable for MT.

An exploration of public perceptions and attitudes towards maggot therapy.

OBJECTIVE: The aim of the study was to explore public opinion and perceptions of maggot therapy (larval therapy), a treatment option for hard-to-heal wounds. METHOD: The study used a mixed-method approach to obtain quantitative and qualitative data. A focus group was convened to explore opinions and views of maggot therapy with a small group of members of the public. Analysis of emerging themes from the focus group was used to design an anonymised web-based survey, which was made available online to members of the public through email and social media. RESULTS: The focus group participants identified four key themes concerning the acceptability of maggot therapy. The subsequent online survey was completed by 412 participants, analysis of which revealed some worries and fears. Only 36% of survey participants agreed that they would accept maggot therapy as a first choice for a hypothetical painful wound, although this number increased with wound severity. The most predominant concerns regarding maggot therapy were sensation and a feeling of disgust associated with the therapy. However, participants could see some benefits to maggot therapy. CONCLUSION: Our study showed that public perception of maggot therapy is varied. Survey participants expressed worries and fears associated with its use. However, positive relationships existed between knowledge scores and potential acceptability of maggot therapy, suggesting that information dissemination and education may be an important factor in public perception and acceptability of maggot therapy.

Synthesis and In Vitro Antimicrobial SAR of Benzyl and Phenyl Guanidine and Aminoguanidine Hydrazone Derivatives.

A series of benzyl, phenyl guanidine, and aminoguandine hydrazone derivatives was designed and in vitro antibacterial activities against two different bacterial strains (Staphylococcus aureus and Escherichia coli) were determined. Several compounds showed potent inhibitory activity against the bacterial strains evaluated, with minimal inhibitory concentration (MIC) values in the low µg/mL range. Of all guanidine derivatives, 3-[2-chloro-3-(trifluoromethyl)]-benzyloxy derivative 9m showed the best potency with MICs of 0.5 µg/mL (S. aureus) and 1 µg/mL (E. coli), respectively. Several aminoguanidine hydrazone derivatives also showed good overall activity. Compounds 10a, 10j, and 10r-s displayed MICs of 4 µg/mL against both S. aureus and E. coli. In the aminoguanidine hydrazone series, 3-(4-trifluoromethyl)-benzyloxy derivative 10d showed the best potency against S. aureus (MIC 1 µg/mL) but was far less active against E. coli (MIC 16 µg/mL). Compound 9m and the para-substituted derivative 9v also showed promising results against two strains of methicillin-resistant Staphylococcus aureus (MRSA). These results provide new and potent structural leads for further antibiotic optimisation strategies.

What is the optimal treatment time for larval therapy? A study on incubation time and tissue debridement by bagged maggots of the greenbottle fly, Lucilia sericata.

The effective use of larvae of the greenbottle fly, Lucilia sericata, in wound debridement requires a working knowledge of how feeding changes over time. Using a laboratory assay and bagged larval dressings, the effect of incubation time on larval feeding rates and body mass was investigated for up to 120 hours at 32°C. The mass of tissue digested increased significantly in incremental 24-hour periods up to 72 hours, with no significant consumption occurring afterwards. Larval mass increased only up to 48 hours. A further test comparing the efficacy of a single 96-hour application of larvae against two consecutive 48-hour applications found that the mass of tissue digested in the latter was 14.3% higher than the former, a difference that was statistically significant. Current clinical guidance suggests a 4-day application period for bagged larvae. Based on these results, an incubation time of 72 hours (3 days) for bagged larvae would be the most effective at the study temperature. However, it is acknowledged that wound temperature can vary, whereby feeding rates would likely differ. In view of this, we conclude that a period of 3 to 4 days is optimum for the application of larvae, and current guidelines should be adhered to.

TIME management by medicinal larvae.

Wound bed preparation (WBP) is an integral part of the care programme for chronic wounds. The acronym TIME is used in the context of WBP and describes four barriers to healing in chronic wounds; namely, dead Tissue, Infection and inflammation, Moisture imbalance and a non-migrating Edge. Larval debridement therapy (LDT) stems from observations that larvae of the blowfly Lucilia sericata clean wounds of debris. Subsequent clinical studies have proven debriding efficacy, which is likely to occur as a result of enzymatically active alimentary products released by the insect. The antimicrobial, anti-inflammatory and wound healing activities of LDT have also been investigated, predominantly in a pre-clinical context. This review summarises the findings of investigations into the molecular mechanisms of LDT and places these in context with the clinical concept of WBP and TIME. It is clear from these findings that biotherapy with L. sericata conforms with TIME, through the enzymatic removal of dead tissue and its associated biofilm, coupled with the secretion of defined antimicrobial peptides. This biotherapeutic impact on the wound serves to reduce inflammation, with an associated capacity for an indirect effect on moisture imbalance. Furthermore, larval serine proteinases have the capacity to alter fibroblast behaviour in a manner conducive to the formation of granulation tissue.

Detection and partial characterization of antifungal bioactivity from the secretions of the medicinal maggot, Lucilia sericata.

The antibacterial properties of the excretions/secretions (ES) of the medicinal maggot, Lucilia sericata have long been known and the effectiveness of maggot debridement therapy in relation to the clearance of bacteria from the surface of wounds has been the source of much research over recent years. Less well known, however, are the antifungal properties of L. sericata ES. Here, we show by means of the colony forming unit assay and optical density assays, that L. sericata native ES possess significant antifungal properties and appears to possess a highly heat stable, freeze/thaw, and lyophilization resistant antifungal component. We also show that the antifungal activity present in the native ES consists of a number of antifungal components present in three fraction masses consisting of >10, 10-0.5, and <0.5 kDa, with the greatest level of activity being seen in the <0.5 kDa fraction.

Multiple actions of Lucilia sericata larvae in hard-to-heal wounds: larval secretions contain molecules that accelerate wound healing, reduce chronic inflammation and inhibit bacterial infection.

In Europe ≈15,000 patients receive larval therapy for wound treatment annually. Over the past few years, clinical studies have demonstrated the success of larvae of Lucilia sericata as debridement agents. This is based on a combination of physical and biochemical actions. Laboratory investigations have advanced our understanding of the biochemical mechanisms underlying the beneficial effects of larval secretions, including removal of dead tissue, reduction of the bacterial burden, and promotion of tissue regeneration. The present article summarizes our current understanding of the microbiological, immunological, and wound healing actions of larval therapy, and the molecules involved in these beneficial effects. Future studies will focus on the isolation, identification, and (pre)clinical testing of the effective molecules of L. sericata larvae. These molecules may be candidates for the development of new agents for the treatment of several infectious and inflammatory diseases, including chronic wounds.

Naturally derived factors and their role in the promotion of angiogenesis for the healing of chronic wounds.

Chronic diseases such as vascular disease and diabetes are witnessing a global increase in prevalence. Such diseases often predispose patients to the development of severe, debilitating, chronic wounds. Angiogenesis, the formation of new capillaries from the pre-existing vascular network, is an essential component of wound healing and aberrant angiogenesis is evident in almost all chronic wounds. Natural products, derived from both plants and animals, provide a significant haven of compounds which have proved to be of great benefit to man and his ailments. Whilst significant advances have been made in the understanding of impaired angiogenesis in a non-healing wound, in the clinical setting, few effective agents exist that can expedite wound healing and closure. The lack of effective healing agents has led to a renewed interest in investigations into natural wound healing resources. In this review, we collate new evidence that details the potential for several natural compounds to promote angiogenesis and wound healing, most predominately via the up regulation of VEGF expression, that warrant urgent further investigation for development into new pro-angiogenic/wound healing therapies.

Lucilia sericata chymotrypsin disrupts protein adhesin-mediated staphylococcal biofilm formation.

Staphylococcus aureus and Staphylococcus epidermidis biofilms cause chronic infections due to their ability to form biofilms. The excretions/secretions of Lucilia sericata larvae (maggots) have effective activity for debridement and disruption of bacterial biofilms. In this paper, we demonstrate how chymotrypsin derived from maggot excretions/secretions disrupts protein-dependent bacterial biofilm formation mechanisms.

Disruption of Staphylococcus epidermidis biofilms by medicinal maggot Lucilia sericata excretions/secretions.

Chronic infections are commonly associated with biofilms formed by bacteria such as Staphylococcus epidermidis. With the increase in antibiotic resistant bacteria, maggot debridement therapy has been reintroduced for the treatment of chronic wounds. Studies have shown that the excretion/ secretions (ES) of Lucilia sericata larvae (maggots) contain many bioactive compounds which may contribute to the efficacy of maggot therapy. The present study evaluates the effect of L. sericata ES on the formation and disruption of S. epidermidis 1457 and 5179-R1 biofilms. These strains employ either polysaccharide intercellular adhesin (PIA) or accumulation associated protein (Aap) for intercellular adhesion. A semiquantitative biofilm assay was used to measure the formation/disruption of S. epidermidis 1457 and 5179-R1 biofilms by ES. ES activity was characterized according to concentration, incubation time and temperature, thermal stability, and size. Immunofluorescence microscopy was used to ascertain the effect of ES on PIA and Aap. In the presence of ES, S. epidermidis 1457 and 5179-R1 nascent biofilm formation was inhibited, and pre-formed biofilms disrupted. ES activity was temperature and time dependent, inactivated by heat treatment, and disruption depended on the mechanism of intercellular adhesion. The molecule(s) responsible was >10 kDa in size and appeared to have protease or glucosaminidase activity. ES interferes with S. epidermidis biofilm formation, specifically degrading factors employed in biofilm accumulation, which would increase bacterial susceptibility to antibiotics and the host's immune system. In purified form, ES-factors may have general applicability for the treatment or prevention of chronic biofilm infections caused by staphylococci.

Effects of bedrest 3: musculoskeletal and immune systems, skin and self-perception.

This is the third article in the series exploring the adverse effects of prolonged bedrest and immobility. In this final article, the effects on the musculoskeletal and immune systems, skin and self-perception are examined.

Effects of bedrest 2: gastrointestinal, endocrine, renal, reproductive and nervous systems.

This article is the second in a three-part series discussing the effects of long periods of bedrest on the body. It explores what happens to the gastrointestinal, endocrine and renal systems when a person is confined to bed. The effects on the reproductive and nervous systems are also covered. Part 1 examined the effects on the cardiovascular, respiratory and haematological systems.

Effects of bedrest 1: cardiovascular, respiratory and haematological systems.

This is the first in a three-part series on the physiological effects of bedrest. It discusses what happens to the cardiovascular, respiratory and haematological systems when a person is bedridden. Other articles in the series will cover the effects of immobility on the digestive, endocrine, renal, nervous, immune and musculoskeletal systems and will examine the effects of bedrest on the skin.