Detection and partial characterisation of two antibacterial factors from the excretions/secretions of the medicinal maggot Lucilia sericata and their activity against methicillin-resistant Staphylococcus aureus (MRSA)

In vitro antibacterial activity and synergetic effect of crude extract of the Wohlfahrtia nuba (Diptera: Sarcophagidae) flesh fly larvae

Multidrug-resistant pathogens have become ubiquitous, and effective treatment alternatives are urgently required. Maggot therapy is a promising agent that is being studied to overcome antibiotic-resistant pathogens. This study evaluated the antibacterial activity of the larvae extract of the Wohlfahrtia nuba (wiedmann) (Diptera: Sarcophagidae) flesh fly on the growth of five pathogenic bacterial species (methicillin-sensitive Staphylococcus aureus [ATCC 29213], methicillin-resistant Staphylococcus aureus [ATCC BAA-1680], Pseudomonas aeruginosa [ATCC 27853], Escherichia coli [ATCC 25922], and Salmonella typhi [ATCC 19430]) in vitro by using different techniques. Resazurin-based turbidimetric assay demonstrated that the W. nuba maggot exosecretion (ES) was potent against all the bacterial species tested, and according to the determined minimum inhibitory concentration (MIC) for each bacterium, gram-negative bacteria were more sensitive than gram-positive bacteria. Additionally, colony-forming unit assay showed that maggot ES was able to inhibit bacterial growth rate for all bacterial species tested, where the highest bacterial reduction was observed with methicillin-sensitive S. aureus (MSSA) followed by S. typhi. Moreover, maggot ES was shown to be concentration-dependent, where 100 μL of ES at 200 mg/mL was bactericidal towards methicillin-resistant S. aureus (MRSA) and P. aeruginosa compared with 100 μL at the MIC of the ES. Moreover, based on the result of agar disc diffusion assay, maggot extract was more efficient against P. aeruginosa and E. coli than the remaining reference strains tested. Furthermore, the combination between regular antibiotics with maggot ES at different concentrations indicated that ES acts synergistically with the tested antibiotics against the five bacterial models.

How Rearing Systems for Various Species of Flies Benefit Humanity

Flies (Diptera) have played a prominent role in human history, and several fly species are reared at different scales and for different beneficial purposes worldwide. Here, we review the historical importance of fly rearing as a foundation for insect rearing science and technology and synthesize information on the uses and rearing diets of more than 50 fly species in the families Asilidae, Calliphoridae, Coelopidae, Drosophilidae, Ephydridae, Muscidae, Sarcophagidae, Stratiomyidae, Syrphidae, Tachinidae, Tephritidae, and Tipulidae. We report more than 10 uses and applications of reared flies to the well-being and progress of humanity. We focus on the fields of animal feed and human food products, pest control and pollination services, medical wound therapy treatments, criminal investigations, and on the development of several branches of biology using flies as model organisms. We highlight the relevance of laboratory-reared Drosophila melanogaster Meigen as a vehicle of great scientific discoveries that have shaped our understanding of many biological systems, including the genetic basis of heredity and of terrible diseases such as cancer. We point out key areas of fly-rearing research such as nutrition, physiology, anatomy/morphology, genetics, genetic pest management, cryopreservation, and ecology. We conclude that fly rearing is an activity with great benefits for human well-being and should be promoted for future advancement in diverse and innovative methods of improving existing and emerging problems to humanity.

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.

Maggot Extract Inhibits Cell Migration and Tumor Growth by Targeting HSP90AB1 in Ovarian Cancer

Ovarian cancer is one of the most lethal gynecological malignancies, because of metastatic dissemination with poor late clinical therapy. Maggots have been used in traditional Chinese medicine, where they are also known as 'Wu Gu Chong'. Previous studies have indicated that maggot extract (ME) was beneficial for the treatment of gastric cancer when combined with other drugs, but the effect on anti-ovarian cancer and the underlying mechanism remains unclear. The aim of this study was to investigate the effects of ME on suppressing the proliferation and migration of ovarian cancer cells, and to clarify the underlying mechanism. In this research, Cell Counting Kit-8 (CCK-8), colony formation assay, and luciferase-positive cell quantification assay were employed to identify the inhibitory effects of ME on cell proliferation. Then, the pro-apoptosis and anti-metastasis effects of ME were explored by Western blot, dual annexin V-fluorescein isothiocyanate/propidium iodide (FITC/PI) assay, immunofluorescent staining, and wound-healing assay. We further established a xenograft model by subcutaneously or intraperitoneally injecting BALB/c nude mice with SKOV3 cells stably expressing luciferase, and the mice were treated with ME. The results showed that ME therapy effectively restrained the growth and metastasis of ovarian tumors in vivo. Furthermore, the mRNA levels of cancer factors including heat shock protein 90 alpha family class B member 1 (HSP90AB1), MYC, and insulin like growth factor 1 receptor (IGF1R) were analyzed by quantitative real-time PCR assay to explore the possible antitumor mechanisms of ME. Next, HSP90 ATPase activity was inhibited by geldanamycin in A2780, and the cell viability was shown to be dramatically reduced, decreasing further with the combination of ME and cisplatin. In turn, HSP90AB1 overexpression effectively inhibited the effect of ME in suppressing capability for cell viability and migration. In addition, HSP90AB1 overexpression limited the ability of ME to inhibit expression of MYC and IGF1R, while the opposite effect was observed for expression of pro-apoptosis protein caspase3 and BAX. Therefore, this study confirmed the potential roles and mechanisms of ME in inhibiting the growth and metastasis of ovarian tumors and promoting apoptosis of ovarian cancer cells by inhibiting overexpression of HSP90AB1.

Antimicrobial potentials of natural products against multidrug resistance pathogens: a comprehensive review

Antibiotic resistance is one of the critical issues, describing a significant social health complication globally. Hence, the discovery of novel antibiotics has acquired an increased attention particularly against drug-resistant pathogens. Natural products have served as potent therapeutics against pathogenic bacteria since the glorious age of antibiotics of the mid 20th century. This review outlines the various mechanistic candidates for dealing with multi-drug resistant pathogens and explores the terrestrial phytochemicals isolated from plants, lichens, insects, animals, fungi, bacteria, mushrooms, and minerals with reported antimicrobial activity, either alone or in combination with conventional antibiotics. Moreover, newly established tools are presented, including prebiotics, probiotics, synbiotics, bacteriophages, nanoparticles, and bacteriocins, supporting the progress of effective antibiotics to address the emergence of antibiotic-resistant infectious bacteria. Therefore, the current article may uncover promising drug candidates that can be used in drug discovery in the future.

Characterization of anti-microbial peptides and proteins from maggots of Calliphoridae and Sarcophagidae fly species (Diptera)

Removal of infected wounds using maggots has been known for centuries. Early research has shown that the maggot exosecretion, whole body, and fecal waste products of Calliphoridae and Sarcophagidae species contain a variety of alkaline peptides capable of inhibiting bacterial growth. Since the wide application of antibiotics such as penicillin, a number of bacterial infections have become insensitive to antibiotic treatment. In many of these instances, maggot therapy has been successfully applied for the treatment of chronic wounds. To identify and compare the expression patterns of anti-microbial peptides (AMPs) from some dipteran species, transcriptome analyses were conducted for the maggots of 11 Calliphoridae and Sarcophagidae species. Species of the subfamily Calliphorinae showed relatively higher expression levels of AMPs and anti-microbial proteins compared with those of Luciliinae and Sarcophagidae species. Furthermore, among all of the dipteran species examined, Lucilia illustris exhibited the highest transcription levels of AMPs. Cecropin A2 and defensin, whose expression levels were the highest among the anti-microbial peptides, were synthesized to test their biological activity. The synthesized peptides showed anti-microbial activities without hemolytic activities. In particular, cecropin A2 of L. illustris exhibited the highest anti-microbial activity against all of the bacteria and fungi examined, thereby possessing the potential to be developed as a new alternative to antibiotics. This comparative transcriptomic study may provide new insights into anti-microbial compositions of some dipteran species.

Safety and efficacy of Lucilia cuprina maggots on treating an induced infected wound in Wistar rats

Infection is one of the main complications that hinder wound healing. Currently, antibiotic-resistant bacteria, such as Methicilin-resistant Staphylococcus aureus (MRSA), are a concern worldwide for both humans and animals. Maggot therapy is re-emerging as an alternative to intractable wounds and may be an option to the traditional antibiotic treatment. Although the species of choice is Lucilia sericata, reports of clinical use have led us to evaluate the efficacy and safety of using Lucilia cuprina larvae on induced infected wounds in Wistar rats. In short, 32 male Wistar rats were divided into 4 groups: Group I - saline solution treated; Group II - antibiotic-treated; Group III - treated with larval debridement, and Group IV - without wound and treatment. Skin wounds were induced in groups I, II and III. All treatments were performed once and held for 48 h. Clinical, microbiological, histopathological, hematological, and biochemical analyses were done. Significant wound area contraction was found (>95%) in group III on day 9 compared to day 15 in group II. Complete elimination (0.0 ± 0.0 CFU/mL) of bioburden was achieved after the second treatment (day 6) in both the II and III groups, compared to an increase in Group I (6.51 ± 0.37 CFU/mL). A cleaner wound was also observed in the histopathological evaluation of group III, with adequate collagen formation and re-epithelialization on day 15. Furthermore, larvae increased blood platelet levels after the first treatment. L. cuprina larvae have proven safe and effective in accelerating wound treatment and eliminating MRSA.

Análisis comparativo de la actividad antimicrobiana de secreciones y excreciones larvales de Calliphora vicina y Sarconesiopsis magellanica (Diptera: Calliphoridae)

Introducción.

La creciente resistencia bacteriana a los antibióticos representa una amenaza mundial de salud pública. Las excreciones y secreciones larvarias derivadas de moscas necrófagas de la familia Calliphoridae podrían configurar una fuente promisoria para contrarrestar sus efectos.

Objetivo.

Comparar la actividad antimicrobiana de las excreciones y secreciones larvarias nativas, y de las mayores y menores de 10 kDa de Calliphora vicina y Sarconesiopsis magellanica (Diptera: Calliphoridae).

Materiales y métodos.

El bioensayo se hizo a partir de la técnica de turbidimetría y en el caso de las excreciones y secreciones menores de 10 kDa se determinó la concentración inhibitoria mínima (CIM).

Resultados.

Las excreciones y secreciones nativas y las menores de 10 kDa de C. vicina y S. magellanica, evidenciaron una potente actividad antibacteriana contra tres cepas de Staphylococcus aureus y cuatro bacterias Gram negativas, siendo las menores de 10 kDa más efectivas que las nativas en las dos especies de moscas evaluadas. Además, las menores de 10 kDa presentaron la misma efectividad, aunque en las pruebas de CIM se observó que las de S. magellanica fueron más potentes en todas las bacterias evaluadas, excepto contra la cepa de S. aureus ATCC 25923. Las mayores de 10 kDa no inhibieron el crecimiento bacteriano.

Conclusión.

Los resultados validaron, en general, que estas sustancias son fuente importante para el aislamiento y la caracterización de agentes antimicrobianos.

Study of the dual biological impacts of aqueous extracts of normal and gamma-irradiated Galleria mellonella larvae

Objectives

Galleria mellonella assimilates beeswax using many gut enzymes; however, high doses of gamma radiation have been used to eradicate such pests, affecting its life cycle. In vitro studies of irradiated extracts of G. mellonella against bacterial species as well as three tumour cell lines are demonstrated in the present study. The antibacterial and antitumour effects are compared with those of the non-irradiated Galleria mellonella larval extract.

Methods

The effect of different dose levels of gamma irradiation, ranging from 2 to 8 Gy, was tested on G. mellonella lipase, protease, and acid phosphate activities. The antimicrobial activity of un-irradiated and irradiated G. mellonella larval extracts was tested against different gram-positive and gram-negative bacteria and some fungi. The antitumour action was tested against different tumour cell lines. A cytotoxicity assay was performed on normal and irradiated larval extracts against normal human lung fibroblast cells. A microscopic examination of Streptococcus mutants and HepG-2 was performed using transmission and scanning electron microscopy.

Results

Optimum results were obtained at 6 Gy, which enhanced maximum enzymatic activity. Maximum antimicrobial activity was obtained against Streptococcus mutants with MIC 31.25 μg/ml at a dose of 6 Gy. A microscopic examination depicted an apoptotic process for irradiated G. mellonella larvae with either Streptococcus mutants or HepG-2.

Conclusion

The present study shows a synergistic relationship between the G. mellonella larval extract and a 6 Gy radiation dose for further biomedical applications.

Maggot debridement therapy to treat hard-to-heal diabetic foot ulcers: a single-centre study

OBJECTIVE

Maggot debridement therapy (MDT) has seen a resurgence in recent years in the treatment of hard-to-heal wounds, as a result of rising antibiotic resistance. The sterilised larvae of Lucilia cuprina have been used in MDT in Malaysia since 2003, with encouraging results for the treatment of hard-to-heal diabetic wounds. We report a case series of 30 patients selected from our clinic by convenient sampling with diabetic lower limb ulcers treated with MDT. The average age of patients receiving MDT was >50 years. Of the 30 patients in the study, nine were female and 21 were male. All patients had underlying diabetes, two patients had leg ulcers and 28 patients had diabetic foot ulcers. Sterilised Lucilia cuprina larvae were applied via a standard method of 10 maggots per square centimetre and dressed with sterile gauze. The study endpoint was defined as ≤5% coverage with slough or necrotic tissue following three successive applications of MDT. In this study, maximum debridement of wounds was achieved in 96.6% (29 patients) of our patients, with ≤5% coverage with slough or necrotic tissue, in addition to a reduction in wound-related pain, as assessed by a visual analogue scale. No adverse events were reported. The findings of this study support the use of MDT as a safe, efficacious, and cost-effective method of managing diabetic wounds.

Health professionals' perceptions of maggot debridement therapy

BACKGROUND

Maggot debridement therapy (MDT), or the use of maggots in dead tissue removal, has been shown to be beneficial in wound healing. Yet MDT in the US is often only used once conventional debridement methods have failed.

METHOD

In this study, nine health professionals, experienced in MDT, were interviewed in order to identify and analyse the perceived societal barriers to MDT acceptance and usage in the US.

RESULTS

Through qualitative analysis, using the grounded theory framework, this study found that among those interviewed, insurance reimbursement restrictions and stigmatisation of medicinal maggots were the factors driving resistance to MDT use.

CONCLUSION

Specifically, the 'yuck' factor and the perception of MDT as an 'ancient' modality contributed towards MDT stigma; in addition, lack of outpatient insurance coverage deterred MDT use. These findings provide useful information regarding the perceptual and systemic barriers that prevent greater acceptance of MDT. Ultimately, these barriers must be understood if we are to facilitate MDT implementation and improve MDT usage in the future.

Salvage of a mangled limb with Matriderm® augmented split-skin grafting and maggot biodebridement

Salvage of a mangled limb can be a long and strenuous way, but it is feasible even with rather simple techniques such as augmented split-skin grafting and maggot biodebridement.

A molecular approach to maggot debridement therapy with Lucilia sericata and its excretions/secretions in wound healing

Chronic wounds caused by underlying physiological causes such as diabetic wounds, pressure ulcers, venous leg ulcers and infected wounds affect a significant portion of the population. In order to treat chronic wounds, a strong debridement, removal of necrotic tissue, elimination of infection and stimulation of granulation tissue are required. Maggot debridement therapy (MDT), which is an alternative treatment method based on history, has been used quite widely. MDT is an efficient, simple, cost-effective and reliable biosurgery method using mostly larvae of Lucilia sericata fly species. Larvae can both physically remove necrotic tissue from the wound site and stimulate wound healing by activating molecular processes in the wound area through the enzymes they secrete. The larvae can stimulate wound healing by activating molecular processes in the wound area through enzymes in their excretions/secretions (ES). Studies have shown that ES has antibacterial, antifungal, anti-inflammatory, angiogenic, proliferative, hemostatic and tissue-regenerating effects both in vivo and in vitro. It is suggested that these effects stimulate wound healing and accelerate wound healing by initiating a direct signal cascade with cells in the wound area. However, the enzymes and peptides in ES are mostly still undefined. Examining the molecular content of ES and the biological effects of these ingredients is quite important to illuminate the molecular mechanism underlying MDT. More importantly, ES has the potential to have positive effects on wound healing and to be used more as a therapeutic agent in the future, so it can be applied as an alternative to MDT in wound healing.

Antibacterial and antifungal activity of excretions and secretions of Calliphora vicina

Antibiotic-resistant bacteria pose a major threat to global health in the 21st century, requiring a quick, cheap and effective response from public health officials. This study evaluated the antimicrobial activity of native excretions/secretions (NES) produced by third instar (3 days old) larvae of Calliphora vicina using a protocol adapted from the Institute of Clinical and Laboratory Standards (CLSI). The microorganisms tested were: Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and the fungus Candida albicans. After the incubation period, the suspensions were diluted and spread on nutrient agar plates to count the colony-forming units. A turbidimetric test also was carried out to test the action of the NES of C. vicina against S. aureus, a very common bacterial species, with an enormous capacity for adaption and resistance, being one of the bacteria of medical importance that causes the most hospital and community infections in the world. According to our results, the NES of C. vicina exhibits antimicrobial activity at different dilutions, being most effective against the gram-negative bacteria E. coli and K. pneumoniae.

Changing attitudes toward maggot debridement therapy in wound treatment: a review and discussion

Maggot debridement therapy is the real-time placement of maggots into a wound by health professionals for the treatment of diabetic ulcers or hard-to-heal wounds infected with antibiotic-resistant bacteria. Maggot debridement therapy shortens healing and disinfects wounds. This paper is a literature review of maggot debridement therapy in the clinical setting today and addresses the costs and benefits of this therapy. It includes recommendations to engage healthcare providers and increase awareness of this therapeutic treatment. A case study is presented on the use of maggot therapy for full debridement of a necrotic wound and clearing of a meticillin-resistant Staphylococcus aureus infection. There is also discussion on how to engage healthcare workers and reduce anxieties about the use of maggots as a treatment for hard-to-heal wounds. Education and awareness are the key factors in changing healthcare workers attitudes to maggot debridement therapy.

Maggot Debridement Therapy in Malaysia

Maggot therapy, also known as maggot debridement therapy, larval therapy, biodebridement, or biosurgery, is a type of biotherapy involving the intentional application of live, disinfected fly larvae or maggots into the nonhealing wound of a human or animal to debride the necrotic wound, reduce bacterial contamination of the wound as well as enhance the formation of healthy granulation tissue and stimulate healing in nonhealing wounds. In addition, van der Plas et al reported that the use of the medicinal larvae as natural remover of necrotic and infected tissue had prevented amputation in 11 selected patients. In Malaysia, Aaron et al had demonstrated prevention of amputation in 25 patients.

Efficacy of Maggot Debridement Therapy on Refractory Atypical Diabetic Foot Ulcers: An Open-Label Study

Atypical or refractory diabetic foot ulcers (DFUs) are still a major health problem. Maggot debridement therapy (MDT) by larva of Lucilia sericata is an ancient and a modern option for wound healing. It works by debridement, stimulation of wound healing, and disinfection. In this study, we aimed to evaluate the efficacy of MDT for healing atypical and refractory DFUs. Patients with atypical DFUs were selected and further evaluated for some predefined differential diagnoses like atypical fungal, parasitic, or bacterial infections, malignancy, trauma, and so on. Multiple MDT sessions were carried out. Ulcer size was measured before every MDT session. Complete wound healing, time to heal, and adverse effects were recorded as well. Forty-two DFU patients (26 men, 16 women) with 42 nonhealing atypical ulcers participated in this study. Complete wound healing was achieved in 35 patients (83.3%) by MDT. Complete debridement and then healing of the wounds happened in less than 1.79 ± 0.8 months. Four ulcers persisted, and 3 (7.1%) were eventually amputated. MDT may be considered as an effective treatment for atypical DFUs, which are unresponsive to conventional therapies.

First Report on the Use of Larvae of Cochliomyia macellaria (Diptera: Calliphoridae) for Wound Treatment in Veterinary Practice

Factors contributing to the delay or prevention of the natural wound healing process include infection and ineffective conventional treatment. Alternative therapies, such as the maggot debridement therapy (MDT), may be helpful for successful treatment in these cases. Aiming to disseminate information about the possibility of using other species of flies for wound treatment, besides the best known Lucilia sericata Meigen, 1826 (Diptera, Calliphoridae), we report here a successful MDT case with the application of Cochliomyia macellaria (Fabricius, 1775) larvae to treat an infected wound with extensive area of necrotic tissue in a dog. Five sterile larvae were applied to each square-cm of lesion and kept on the animal for only 48 h. The healing was successful, from both qualitative and quantitative points of view. The ratio of wound healing (RWH) reached almost 50% on the 5th day and 100% on the 14th day after MDT. Although the overall animal prognosis had been unfavorable, mainly due to the sepsis, the patient began to recover and had improved clinical condition from the fifth day after MDT. This study shows the importance and effectiveness of MDT in promoting faster and more complete healing of a complex wound.

Proline-Rich Antimicrobial Peptides in Medicinal Maggots of Lucilia sericata Interact With Bacterial DnaK But Do Not Inhibit Protein Synthesis

In the search for new antibiotics to combat multidrug-resistant microbes, insects offer a rich source of novel anti-infectives, including a remarkably diverse array of antimicrobial peptides (AMPs) with broad activity against a wide range of species. Larvae of the common green bottle fly Lucilia sericata are used for maggot debridement therapy, and their effectiveness in part reflects the large panel of AMPs they secrete into the wound. To investigate the activity of these peptides in more detail, we selected two structurally different proline rich peptides (Lser-PRP2 and Lser-PRP3) in addition to the α-helical peptide Lser-stomoxyn. We investigated the mechanism of anti-Escherichia coli action of the PRPs in vitro and found that neither of them interfered with protein synthesis but both were able to bind the bacterial chaperone DnaK and are therefore likely to inhibit protein folding. However, unlike Lser-stomoxyn that permeabilized the bacterial membrane by 1% at the low concentration (0.25 µM) neither of the PRPs alone was able to permeabilize E. coli membrane. In the presence of this Lser-stomoxyn concentration significant increase in anti-E. coli activity of Lser-PRP2 was observed, indicating that this peptide needs specific membrane permeabilizing agents to exert its antibacterial activity. We then examined the AMPs-treated bacterial surface and observed detrimental structural changes in the bacterial cell envelope in response to combined AMPs. The functional analysis of insect AMPs will help select optimal combinations for targeted antimicrobial therapy.

Antiviral and virucidal activities of Lucilia cuprina maggots' excretion/secretion (Diptera: Calliphoridae): first work

Maggots of Lucilia sericata and L. cuprina are a backbone of the maggot debridement therapy. Further, the excretion/secretion (E/S) of these maggots has antibacterial and antifungal activities, nevertheless the antiviral activity of E/S for these maggots still out the focus. This study aimed to evaluate the E/S of L. cuprina maggots against the Rift Valley Fever (RVF) and Coxsackie B4 (CB4) viruses for first time. After collection of the E/S, its cytotoxicity on Vero cells was evaluated and the safe concentration was determined which used to investigate the antiviral and virucidal effect of E/S on the selected viruses. The E/S decreased the titers of the tested viruses compared with that of untreated viruses. The outcome data refer to that the E/S of L. cuprina consider as a promising antiviral and virucidal agent.

Bactericidal Activity of Chrysomya rufifacies and Cochliomyia macellaria (Diptera: Calliphoridae) Larval Excretions-Secretions Against Staphylococcus aureus (Bacillales: Staphylococcaceae)

The inhibitory effect of Chrysomya rufifacies (Macquart) and Cochliomyia macellaria (Fabricius) larval excretions-secretions (ES) on Staphylococcus aureus was determined using a portable colorimetric method without the need for any dedicated spectral instrument. Polystyrene 96 well microplates were used and 100 μl of the bacterial inoculum (5 × 105 CFU/ml) plus 100 μl of the dipteran exosecretions at different concentrations were added to each well. Subsequently, 50 μl of a 1% solution of the triphenyl tetrazolium chloride stain was added to each well to determine the bacterial viability. The color development in each well was measured with the ImageJ software S. aureus was exposed to different concentrations of the ES of both species individually. At a concentration of 800 ppm ES of C. rufifacies or Co. macellaria, bacterial growth was inhibited 97.45 ± 1.70% and 82.21 ± 1.88%, respectively. As expected, exposure to a lower concentration (i.e., 50 ppm) was less inhibitory (C. rufifacies ES, 77.65 ± 4.25% and Co. macellaria ES, 43.54 ± 4.63%). This study demonstrates for the first time the bactericidal activity of C. rufifacies and Co. macellaria ES against S. aureus. This finding is promising as it could result in the identification and synthesis of proteins capable of suppressing pathogen development in wounds. Additionally, the proposed method can simplify the use of expensive laboratory instruments for antimicrobial activity determination.

In vitro evaluation of the association of medicinal larvae (Insecta, Diptera, Calliphoridae) and topical agents conventionally used for the treatment of wounds

Wound healing is a complex process involving multiple biochemical and cellular events and represents a neglected public health issue. As a consequence, millions of people worldwide suffer from chronic wounds. The search for new treatment alternatives is therefore an important issue. In the context of wound healing, Maggot Debridement Therapy (MDT) is an inexpensive treatment with few contraindications and very promising results. This study aimed to evaluate the in vitro feasibility and implications of larvae (= MDT) use when combined with topical agents as a strategy to identify additive or synergistic combinations. The weight and survival rate of Cochliomyia macellaria (Fabricius) (Insecta, Diptera, Calliphoridae) larvae reared in an in vitro wound with either honey, hydrogel, 10% papain gel, essential fatty acids (EFA), collagenase, or silver sulfadiazine were evaluated after 24, 48 and 72 h. Hydrogel (for weight: 24 and 72 h; for survival: 24 h) and 10% papain gel (for weight: 48 h; for survival: 48 and 72 h) demonstrated the least interference in larval weight gain and survival rate, when compared to the control group. The results obtained in this study showed that the combined use of larvae and hydrogel or 10% papain gel may be promising to maximize the tissue repair. Honey, EFA and collagenase could be used to prepare the bed of the dry wounds to receive the MDT.

Looking for the right mate-What we really know on the courtship and mating of Lucilia sericata (Meigen)?

Lucilia sericata is well known for causing myiasis in humans, livestock, pets and wildlife. It also vectors microbial pathogens, including paratuberculosis agents. This species can be exploited in maggot therapy to treat necrotic wounds, particularly those infected by multidrug-resistant pathogens. Despite its high medical and veterinary importance, our knowledge about its courtship and mating behavior is still limited. In this study, we quantified the courtship and mating behavior of L. sericata, shedding light on the potential impact of lateralization of selected behavioral traits during sexual interactions. When a male identified a female, he approached her with head pushing followed by foreleg tapping acts. Courtship lasted 7.65 ± 0.4 s. During copulation attempts, the male continued foreleg tapping acts on the female body, and tried to achieve genital contact. Copula lasted 14.88 ± 0.41 min, while male mating success was 85%. Several courtship and mating traits were found lateralized at population-level. Most of males approached the female with head pushing acts on her left side of the body. Both during courtship and copulation attempt phases, males mainly used the right foreleg to perform leg tapping acts on females. However, the impact of lateralized head pushing and foreleg tapping on the main behavioral parameters characterizing L. sericata courtship and mating was not significant, except for a higher number of foreleg tapping acts during copulation attempts displayed by right-biased males over left-biased ones. Overall, these results contribute to improve our basic knowledge on the reproductive behavior of L. sericata. Besides, selected behavioral parameters characterized here can be exploited as benchmarks to monitor mate quality during mass-rearing, as well as to select males with boosted mating competitiveness, helping to improve the success of SIT programs and behavior-based control tools.

Sarconesin: Sarconesiopsis magellanica Blowfly Larval Excretions and Secretions With Antibacterial Properties

Larval therapy (LT) is an alternative treatment for healing chronic wounds; its action is based on debridement, the removal of bacteria, and stimulating granulation tissue. The most important mechanism when using LT for combating infection depends on larval excretions and secretions (ES). Larvae are protected against infection by a spectrum of antimicrobial peptides (AMPs); special interest in AMPs has also risen regarding understanding their role in wound healing since they degrade necrotic tissue and kill different bacteria during LT. Sarconesiopsis magellanica (Diptera: Calliphoridae) is a promising medically-important necrophagous fly. This article reports a small AMP being isolated from S. magellanica ES products for the first time; these products were obtained from third-instar larvae taken from a previously-established colony. ES were fractionated by RP-HPLC using C18 columns for the first analysis; the products were then lyophilised and their antimicrobial activity was characterized by incubation with different bacterial strains. These fractions' primary sequences were determined by mass spectrometry and de novo sequencing; five AMPs were obtained, the Sarconesin fraction was characterized and antibacterial activity was tested in different concentrations with minimum inhibitory concentrations starting at 1.2 μM. Potent inhibitory activity was shown against Gram-negative (Escherichia coli D31, E. coli DH5α, Salmonella enterica ATCC 13314, Pseudomonas aeruginosa 27853) and Gram-positive (Staphylococcus aureus ATCC 29213, S. epidermidis ATCC 12228, Micrococcus luteus A270) bacteria. Sarconesin has a significant similarity with Rho-family GTPases which are important in organelle development, cytoskeletal dynamics, cell movement, and wound repair. The data reported here indicated that Sarconesin could be an alternative candidate for use in therapeutics against Gram-negative and Gram-positive bacterial infections. Our study describes one peptide responsible for antibacterial activity when LT is being used. The results shown here support carrying out further experiments aimed at validating S. magellanica AMPs as novel resources for combating antibacterial resistance.

Identification, Characterization, Immunolocalization, and Biological Activity of Lucilin Peptide

Maggots from the Lucilia sp. genus are used for debridement of infected and necrotic wounds. Broad-spectrum antimicrobial activity has been described in the excretion/secretions (ES¹) of these larvae. This study identifies the genetic sequence of a cecropin-like antimicrobial peptide from Lucilia eximia. Total RNA was extracted and used for PCR-RACE amplification of a cecropin, the native peptide was immunolocalized in the tissues and secretions of the larvae, and a synthetic analog was used to explore its antimicrobial, cytotoxic, LPS neutralizing and wound-healing activities in vitro. The genetic cDNA sequence of a cecropin-like antimicrobial peptide in L. eximia called "Lucilin" was amplified, corresponding to 63 aa completed protein and 40 aa mature peptide; the structure of the mature peptide was predicted as an α-helix. The peptide was immunolocalized in the salivary glands, fat body, the ES, and hemolymph of the maggots. Lucilin synthetic peptide analog was active against E. coli DH10B with a MIC² of 7.8 μg/mL, E. coli extended spectrum b-lactamase (ESBL) (MIC: 15.6 μg/mL), and Enterobacter cloacae (MIC: 125 μg/mL), but it was not active against Pseudomonas aeruginosa and Staphylococcus epidermidis; and had no cytotoxic or hemolytic activity. It showed immunomodulatory activity against human peripheral blood mononuclear cells (PBMCs) stimulated with LPS, reducing the TNF-α production when treated at 17 μg/mL and induces cell migration of Hacat at 5 and 50 μg/mL. Lucilin is a cecropin-like peptide from L. eximia with antimicrobial activity against Gram negative bacteria and immunomodulatory activities, decreasing the TNF-α production in PBMCs and inducing cellular migration in human keratinocytes.

Pharmacological Properties of the Medical Maggot: A Novel Therapy Overview

In the last decade, maggot has been hailed as the miraculous “medicinal maggot” for its diverse properties, including antimicrobial, antibiofilm, anti-inflammatory, and wound healing activities. The fact that maggots show so many beneficial properties has increased the interest in these tiny larvae dramatically. Whilst there is relatively abundant clinical evidence to demonstrate the success of maggots as debridement agents, not so much emphasis has been placed on the basic science evidence, which was a combination of physical and biochemical actions. This review differs from those earlier works in that it is undertaken to provide an update of the latest scientific basis published on maggot, particularly active ingredients within maggot excretions/secretions (ES). Further investigations should focus on the isolation, identification, recombination, transgenosis, and mass production of the beneficial molecules within maggots.

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 7457 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 7457 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 7457 and 5179-R1 nascent bio film 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.

Evaluating the anti-leishmania activity of Lucilia sericata and Sarconesiopsis magellanica blowfly larval excretions/secretions in an in vitro model

Leishmaniasis is a vector-borne disease caused by infection by parasites from the genus Leishmania. Clinical manifestations can be visceral or cutaneous, the latter mainly being chronic ulcers. This work was aimed at evaluating Calliphoridae Lucilia sericata- and Sarconesiopsis magellanica-derived larval excretions and secretions' (ES) in vitro anti-leishmanial activity against Leishmania panamensis. Different larval-ES concentrations from both blowfly species were tested against either L. panamensis promastigotes or intracellular amastigotes using U937-macrophages as host cells. The Alamar Blue method was used for assessing parasite half maximal inhibitory concentration (IC₅₀) and macrophage cytotoxicity (LC₅₀). The effect of larval-ES on L. panamensis intracellular parasite forms was evaluated by calculating the percentage of infected macrophages, parasite load and toxicity. L. sericata-derived larval-ES L. panamensis macrophage LC₅₀ was 72.57μg/mL (65.35-80.58μg/mL) and promastigote IC₅₀ was 41.44μg/mL (38.57-44.52μg/mL), compared to 34.93μg/mL (31.65-38.55μg/mL) LC₅₀ and 23.42μg/mL (22.48-24.39μg/mL) IC₅₀ for S. magellanica. Microscope evaluation of intracellular parasite forms showed that treatment with 10μg/mL L. sericata ES and 5μg/mL S. magellanica ES led to a decrease in the percentage of infected macrophages and the amount of intracellular amastigotes. This study produced in vitro evidence of the antileishmanial activity of larval ES from both blowfly species on different parasitic stages and showed that the parasite was more susceptible to the ES than it's host cells. The antileishmanial effect on L. panamensis was more evident from S. magellanica ES.

Evaluation of Sterilized Artificial Diets for Mass Rearing the Lucilia sericata (Diptera: Calliphoridae)

The impact of six sterilized diets (blood-yeast agar diet, decomposed beef liver diet, powdered beef liver diet, powdered fish diet, milk-based diet, and a chemically defined diet) on Lucilia sericata (Meigen) larvae reared at three densities (10 larvae, 20 larvae, and 40 larvae on 20 g diet) was determined in comparison to fresh beef liver as a control. Specifically, the effects of these diets on the following traits of L. sericata were measured: 1) pupal weight, 2) pupation percentage, 3) eclosion percentage, as well as 4) adult longevity. The experiment included two trials with five technical replicates in each. Lucilia sericata did not successfully develop on the powdered fish, milk-based, or chemically defined diets. Overall, the liver-based diets (decomposed and powdered) resulted in the most similar fly development to the fresh beef liver. Larvae reared on blood-yeast agar diet resulted in a significantly (increased 20.56% ± 8.09%) greater pupation rate than those reared on the decomposed and powdered beef liver diets. Pupae from larvae fed the fresh beef liver were significantly larger (6.27 ± 1.01 mg, 4.05 ± 0.94 mg larger, respectively) than those reared on the blood-yeast agar diet, decomposed beef liver, and powdered beef liver diets. Overall, results revealed larvae reared on sterilized liver-based diets resulted in traits similar to those raised on fresh beef liver. Owing to low costs the sterile liver-based diets could be produced and used with limited infrastructure and economic incomes.

Nonconsumptive Effects of Predatory Chrysomya rufifacies (Diptera: Calliphoridae) Larval Cues on Larval Cochliomyia macellaria (Diptera: Calliphoridae) Growth and Development

Forensic entomologists often rely on development data associated with a given species to estimate when it colonized human or other vertebrate remains. In most instances, these development studies are based on single species reared in isolation in the laboratory. This study examined the impact of excretions and secretions (ES) associated with third-instar Chrysomya rufifacies (Macquart), a predator, on the development of its prey, Cochliomyia macellaria (F.). Not surprisingly, Ch. rufifacies ES did not impact the development of first- or second-instar C. macellaria, which are typically not preyed on by Ch. rufifacies. However, development of third-instar C. macellaria, which do experience predation, was impacted. First, larvae were longer than those in the control (deionized water, dH2O). Filtering the ES and removing the associated bacteria and byproducts >0.2 µm dampened the previous impact observed by the unfiltered ES on third-instar C. macellaria. Second, third-instar C. macellaria treated with unfiltered ES completed pupariation 8 h quicker than the controls. Filtering the ES lessened this effect by 50%. And finally, third-instar C. macellaria treated with filtered or unfiltered Ch. rufifacies ES reached adulthood ∼5 h faster than controls treated with dH2O. In summary, these data have large ramifications for forensic entomology, as multiple species being present on decomposing remains is not uncommon. Understanding the impact of associated ES produced by interspecific cohorts on associated development could lead to more precise estimates of the minimum postmortem interval for forensic investigation of decomposing remains.

Insect Artifacts Are More than Just Altered Bloodstains

The bases for forensic entomology are that insects and their arthropod relatives can serve as evidence in criminal, medical and civil legal matters. However, some of the very same species that provide utility to legal investigations can also complicate crime scenes by distorting existing body fluid evidence (e.g., bloodstains, semen, saliva) and/or depositing artifacts derived from the insect alimentary canal at primary or secondary crime scenes. The insect contaminants are referred to as insect stains, artifacts, specks or spots, and are most commonly associated with human bloodstains. This review will discuss the different types of insect artifacts that have been described from crime scenes and laboratory experiments, as well as examine insect contaminates (non-blood based artifacts, transfer patterns, meconium, and larval fluids) that have received little research or case attention. Methods currently used for distinguishing insect stains from human body fluids will also be discussed and compared to presumptive tests used for identification of human body fluids. Since all available methods have severe limitations, areas of new research will be identified for the purpose of development of diagnostic techniques for detection of insect artifacts.

First Record of Larval Secretions of Cochliomyia macellaria (Fabricius, 1775) (Diptera: Calliphoridae) Inhibiting the Growth of Staphylococcus aureus and Pseudomonas aeruginosa

Maggot debridement therapy (MDT) consists on the intentional and controlled application of sterilized larvae of the order Diptera on necrotic skin lesions with the purpose of cleaning necrotic tissue and removing pathogenic bacteria. During MDT, a marked antimicrobial activity has been reported in literature specially associated with antibacterial substances from Lucilia sericata (Meigen); however, regarding Cochliomyia macellaria (Fabricius), little is known. This study aimed to evaluate in vitro inhibition of bacterial growth of Pseudomonas aeruginosa and Staphylococcus aureus in contact with excretions and secretions (ES) from C. macellaria larvae. Larval ES were extracted in sterile distilled water and divided in three groups: ES, containing 400 μL of autoclaved ES; ES+BAC, containing 400 μL of autoclaved ES+0.5-μL bacterial inoculum; and CONT-BAC, containing 400 μL of sterile distilled water +0.5 μL of bacterial inoculum. Aliquots of each experimental group were plated by spreading onto Petri dishes. Seedings were made at 0, 1, 2, 4, and 12 h after the extraction of ES. In ES+BAC groups, inhibition of S. aureus was verified between times 1 and 2 h and P. aeruginosa was inhibited between 0 and 4 h. There was no growth observed in any ES group. In the CONT-BAC groups, the number of colonies from time 4 h became countless for S. aureus and decreased for P. aeruginosa. As reported in the literature, we note here that ES have excellent bactericidal activity for both gram-positive and gram-negative bacteria, and this study shows for the first time the action of the bactericidal activity of exosecretions of C. macellaria against S. aureus and P. aeruginosa.

Genome sequence of Phormia regina Meigen (Diptera: Calliphoridae): implications for medical, veterinary and forensic research

BACKGROUND

Blow flies (Diptera: Calliphoridae) are important medical, veterinary and forensic insects encompassing 8 % of the species diversity observed in the calyptrate insects. Few genomic resources exist to understand the diversity and evolution of this group.

RESULTS

We present the hybrid (short and long reads) draft assemblies of the male and female genomes of the common North American blow fly, Phormia regina (Diptera: Calliphoridae). The 550 and 534 Mb draft assemblies contained 8312 and 9490 predicted genes in the female and male genomes, respectively; including > 93 % conserved eukaryotic genes. Putative X and Y chromosomes (21 and 14 Mb, respectively) were assembled and annotated. The P. regina genomes appear to contain few mobile genetic elements, an almost complete absence of SINEs, and most of the repetitive landscape consists of simple repetitive sequences. Candidate gene approaches were undertaken to annotate insecticide resistance, sex-determining, chemoreceptors, and antimicrobial peptides.

CONCLUSIONS

This work yielded a robust, reliable reference calliphorid genome from a species located in the middle of a calliphorid phylogeny. By adding an additional blow fly genome, the ability to tease apart what might be true of general calliphorids vs. what is specific of two distinct lineages now exists. This resource will provide a strong foundation for future studies into the evolution, population structure, behavior, and physiology of all blow flies.

Genome Sequence of a Proteus mirabilis Strain Isolated from the Salivary Glands of Larval Lucilia sericata

We announce a draft genome sequence of a Proteus mirabilis strain derived from Lucilia sericata salivary glands. This strain is demonstrated to attract and induce oviposition by L. sericata, a common blow fly important to medicine, agriculture, and forensics. The genome sequence will help dissect interkingdom communication between the species.

Viability of Lucilia sericata maggots after exposure to wound antiseptics

After debridement and before dressing a wound with maggots of calliphorid flies, one frequently performed step is the application of antiseptics to the prepared wound bed. However, the concomitant application of antiseptic agents during maggot therapy is regarded controversial as antiseptics may interfere with maggots' viability. In this experimental in vitro study, the viability of fly maggots was investigated after exposure to various antiseptics frequently used in wound care. Here, we show that Lucilia sericata fly maggots can survive up to an hour's exposure to wound antiseptics such as octenidine, povidone-iodine or polihexanide. Concomitant short-term application of wound antiseptics together with maggots on wound beds is tolerated by larvae and does not impair their viability.

Traditional Therapies for Skin Wound Healing

Significance: The regeneration of healthy and functional skin remains a huge challenge due to its multilayer structure and the presence of different cell types within the extracellular matrix in an organized way. Despite recent advances in wound care products, traditional therapies based on natural origin compounds, such as plant extracts, honey, and larvae, are interesting alternatives. These therapies offer new possibilities for the treatment of skin diseases, enhancing the access to the healthcare, and allowing overcoming some limitations associated to the modern products and therapies, such as the high costs, the long manufacturing times, and the increase in the bacterial resistance. This article gives a general overview about the recent advances in traditional therapies for skin wound healing, focusing on the therapeutic activity, action mechanisms, and clinical trials of the most commonly used natural compounds. New insights in the combination of traditional products with modern treatments and future challenges in the field are also highlighted. Recent Advances: Natural compounds have been used in skin wound care for many years due to their therapeutic activities, including anti-inflammatory, antimicrobial, and cell-stimulating properties. The clinical efficacy of these compounds has been investigated through in vitro and in vivo trials using both animal models and humans. Besides the important progress regarding the development of novel extraction methods, purification procedures, quality control assessment, and treatment protocols, the exact mechanisms of action, side effects, and safety of these compounds need further research. Critical Issues: The repair of skin lesions is one of the most complex biological processes in humans, occurring throughout an orchestrated cascade of overlapping biochemical and cellular events. To stimulate the regeneration process and prevent the wound to fail the healing, traditional therapies and natural products have been used with promising results. Although these products are in general less expensive than the modern treatments, they can be sensitive to the geographic location and season, and exhibit batch-to-batch variation, which can lead to unexpected allergic reactions, side effects, and contradictory clinical results. Future Directions: The scientific evidence for the use of traditional therapies in wound healing indicates beneficial effects in the treatment of different lesions. However, specific challenges remain unsolved. To extend the efficacy and the usage of natural substances in wound care, multidisciplinary efforts are necessary to prove the safety of these products, investigate their side effects, and develop standard controlled trials. The development of good manufacturing practices and regulatory legislation also assume a pivotal role in order to improve the use of traditional therapies by the clinicians and to promote their integration into the national health system. Current trends move to the development of innovative wound care treatments, combining the use of traditional healing agents and modern products/practices, such as nanofibers containing silver nanoparticles, Aloe vera loaded into alginate hydrogels, propolis into dressing films, and hydrogel sheets containing honey.

New Is Old, and Old Is New: Recent Advances in Antibiotic-Based, Antibiotic-Free and Ethnomedical Treatments against Methicillin-Resistant Staphylococcus aureus Wound Infections

Staphylococcus aureus is the most common pathogen of wound infections. Thus far, methicillin-resistant S. aureus (MRSA) has become the major causative agent in wound infections, especially for nosocomial infections. MRSA infections are seldom eradicated by routine antimicrobial therapies. More concerning, some strains have become resistant to the newest antibiotics of last resort. Furthermore, horizontal transfer of a polymyxin resistance gene, mcr-1, has been identified in Enterobacteriaceae, by which resistance to the last group of antibiotics will likely spread rapidly. The worst-case scenario, "a return to the pre-antibiotic era", is likely in sight. A perpetual goal for antibiotic research is the discovery of an antibiotic that lacks resistance potential, such as the recent discovery of teixobactin. However, when considering the issue from an ecological and evolutionary standpoint, it is evident that it is insufficient to solve the antibiotic dilemma through the use of antibiotics themselves. In this review, we summarized recent advances in antibiotic-based, antibiotic-free and ethnomedical treatments against MRSA wound infections to identify new clues to solve the antibiotic dilemma. One potential solution is to use ethnomedical drugs topically. Some ethnomedical drugs have been demonstrated to be effective antimicrobials against MRSA. A decline in antibiotic resistance can therefore be expected, as has been demonstrated when antibiotic-free treatments were used to limit the use of antibiotics. It is also anticipated that these drugs will have low resistance potential, although there is only minimal evidence to support this claim to date. More clinical trials and animal tests should be conducted on this topic.

Next Generation Sequencing Identifies Five Major Classes of Potentially Therapeutic Enzymes Secreted by Lucilia sericata Medical Maggots

Lucilia sericata larvae are used as an alternative treatment for recalcitrant and chronic wounds. Their excretions/secretions contain molecules that facilitate tissue debridement, disinfect, or accelerate wound healing and have therefore been recognized as a potential source of novel therapeutic compounds. Among the substances present in excretions/secretions various peptidase activities promoting the wound healing processes have been detected but the peptidases responsible for these activities remain mostly unidentified. To explore these enzymes we applied next generation sequencing to analyze the transcriptomes of different maggot tissues (salivary glands, gut, and crop) associated with the production of excretions/secretions and/or with digestion as well as the rest of the larval body. As a result we obtained more than 123.8 million paired-end reads, which were assembled de novo using Trinity and Oases assemblers, yielding 41,421 contigs with an N50 contig length of 2.22 kb and a total length of 67.79 Mb. BLASTp analysis against the MEROPS database identified 1729 contigs in 577 clusters encoding five peptidase classes (serine, cysteine, aspartic, threonine, and metallopeptidases), which were assigned to 26 clans, 48 families, and 185 peptidase species. The individual enzymes were differentially expressed among maggot tissues and included peptidase activities related to the therapeutic effects of maggot excretions/secretions.

Maggot debridement therapy promotes diabetic foot wound healing by up-regulating endothelial cell activity

To determine the role of maggot debridement therapy (MDT) on diabetic foot wound healing, we compared growth related factors in wounds before and after treatment. Furthermore, we utilized human umbilical vein endothelial cells (HUVECs) to explore responses to maggot excretions/secretions on markers of angiogenesis and proliferation. The results showed that there was neo-granulation and angiogenesis in diabetic foot wounds after MDT. Moreover, significant elevation in CD34 and CD68 levels was also observed in treated wounds. In vitro, ES increased HUVEC proliferation, improved tube formation, and increased expression of vascular endothelial growth factor receptor 2 in a dose dependent manner. These results demonstrate that MDT and maggot ES can promote diabetic foot wound healing by up-regulating endothelial cell activity.

Use of maggot therapy for treating a diabetic foot ulcer colonized by multidrug resistant bacteria in Brazil

This study reports the efficacy of maggot therapy in the treatment of diabetic foot ulcer infected with multidrug resistant microorganisms. A 74 year old female patient with diabetes for over 30 years, was treated with maggot therapy using larvae of Chrysomya megacephala. The microbiological samples were collected to evaluate aetiology of the infection. The therapy done for 43 days resulted in a reduction of necrosis and the ulcer's retraction of 0.7 cm [2] in area. Analysis of the bacteriological swabs revealed the presence of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa. Further studies need to be done to confirm the role of maggot therapy in wound healing using a large sample and a proper study design.

Evaluating Sarconesiopsis magellanica blowfly-derived larval therapy and comparing it to Lucilia sericata-derived therapy in an animal model

Larval therapy is used as alternative treatment for hard-to-heal chronic and infected wounds. Lucilia sericata is the most used blowfly species. However, it has been shown recently that Sarconesiopsis magellanica larval excretions and secretions have potent antibacterial activity; this blowfly belongs to the Calliphoridae family. The present work has dealt with evaluating larval therapy using S. magellanica on wounds induced in diabetic rabbits and its action was compared to the effect induced by L. sericata. Twelve New Zealand White rabbits (Oryctolagus cuniculus) were used; they were divided into 4 groups, the first two being treated with larval therapy derived from both aforementioned necrophagous blowflies, an antibiotic was used in the third and the fourth was used as control. All the animals were wounded on the back and infected with Pseudomonas aeruginosa and Staphylococcus aureus. Samples of the secretion from each animal's infected wound were taken and sown on blood agar. The colony forming units were then counted. The PUSH scale was used for the macroscopic evaluation of the wounds. Bacterial control was encountered 48 h post-treatment in the treatments involving larval therapy and to a lesser extent with the antibiotic. Likewise, wound debridement was quicker and more efficient with larval therapy compared to the antibiotic group; however, wound closing time was 23 days in all treatments. The group treated with S. magellanica larvae had relatively quicker evolution until the proliferation phase and the start of maturation, even though there were no significant differences between both blowfly species evaluated here regarding treatments by the end of the treatment period. The present study has validated the diabetic rabbit model for inducing chronic wounds regarding larval therapy and has likewise confirmed the effectiveness of S. magellanica-derived larval therapy as an alternative for curing and healing wounds.

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 preliminary physico-chemical properties of antimicrobial components in the native excretions/secretions of three species of Chrysomya (Diptera, Calliphoridae) in Brazil

Antibiotic-resistant bacteria in hospitals and communities increasingly threaten public health in Brazil and the rest of the World. There is an urgent need for additional antimicrobial drugs. Calliphorid blowfly larvae are a rich source of antimicrobial factors but the potential of Neotropical species has been neglected. This preliminary study evaluates the antimicrobial activity of the native excretions/secretions of larvae of three species of Brazilian calliphorids, Chrysomya megacephala, Chrysomya albiceps and Chrysomya putoria. Native excretions/secretions were collected from third instar larvae, sterile filtered and tested for antibacterial activity against Staphylococcus aureus 9518, Escherichia coli K12 4401 and Serratia marcescens 365. Turbidometric assays were made in micro-plates, using an ELISA reader, with readings taken up to 22 h. Bacterial suspensions at the start and end of each experiment were also serially diluted, spread on nutrient agar plates and then colony forming units counted. The physico-chemical characteristics of the native excretions/secretions were also tested by freezing/thawing, boiling, and protease digestion. The native excretions/secretions of larvae from these three Chrysomya species significantly inhibited bacterial growth. Therefore, Brazilian calliphorid flies could potentially provide new classes of antibiotics.