SLR- November 2022- Patricia Woo, DPM
Title: Microbiological Effects in Patients with Leg Ulcers and Diabetic Foot Treated with Lucilia sericata Larvae.Reference: Szczepanowski Z, Grabarek BO, Boroń D, Tukiendorf A, Kulik-Parobczy I, Miszczyk L. Microbiological effects in patients with leg ulcers and diabetic foot treated with Lucilia sericata larvae. Int Wound J. 2022 Jan;19(1):135-143. doi: 10.1111/iwj.13605. Epub 2021 May 4. PMID: 33942509; PMCID: PMC8684863.
Level of Evidence: IV
Scientific Literature Review
Reviewed By: Patricia Woo, DPM
Residency Program: North Colorado Medical Center – Greeley, CO
Podiatric Relevance:
Lower extremity wounds are prevalent in podiatric medicine and infection may lead to acute complications or limb threatening injuries. Historically, larvae have been used to decrease bioburden and bacteria while promoting healing of wounds. As the development of antibiotics grew to combat infection, the use of larval therapy became antiquated. However, larval therapy may still provide an effective therapy in contemporary treatment of lower extremity wounds.
Methods:
One hundred twenty nine patients from Kędzierzyn-Kozle, Poland, with lower limb ulceration or diabetic foot ulcers between 2010 to 2012 participated in this study. Inclusion criteria included chronic wounds with necrosis and purulence in the calf or feet areas and those with compensated DM (Diabetes Mellitus). Exclusion criteria included wounds lacking necrosis, exudates, traumatic wounds, bedsores, cancer ulcers, and burn wounds. Eighty patients underwent MDT (Maggot debridement therapy) while 40 patients were excluded and underwent ozone therapy. The eighty patients undergoing MDT were further sub-divided into 4 groups based on location of ulcer (foot/leg) and number of larvae applied (5 vs. 10). Before therapy, wounds were cleansed with 0.9% NaCl solution before a microbial swab was performed. Additional micro-assessments were taken after therapy completion. A clinical result of healing was considered for wounds with a >50% decrease in wound size at the conclusion of the study.
Results:
Twenty-three different species of bacteria were identified in the wounds before and after therapy.
Group 1: Diabetic foot ulcer with 5 larvae per cm2
Pre-therapy: Streptococcus B haemolyticus (24%); Streptococcus coagulase negative (19%)
Post-therapy: Proteus species (46%) and Enterobacteriaceae (23%)
Group 2: Diabetic foot ulcer with 10 larvae per cm2
Pre-therapy: Staphylococcus aureus (37%)
Post-therapy: Proteus species (29%) and Proteus mirabilis (21%).
Group 3: Lower leg ulcer with 5 larvae per cm2
Pre-therapy: Pseudomonas aeruginosa (20%) and Staphylococcus aureus (14%)
Post-therapy: Pseudomonas aeruginosa and Staphylococcus aureus (17% each)
Group 4: Lower leg ulcer with 10 larvae per cm2
Pre-therapy: Staphylococcus aureus (32%), Streptococcus B haemolyticus (16%)
Post-therapy: Proteus species (53%) and Proteus mirabilis (29%)
Group 5: Diabetic foot ulcer with Ozone therapy
Pre-therapy: Staphylococcus aureus (23%), Streptococcus B haemolyticus (23%)
Post-therapy: Proteus species (32%) and Staphylococcus aureus (32%).
Group 6: Lower leg ulcer with Ozone therapy
Pre-therapy: Staphylococcus aureus (20%) and Pseudomonas aeruginosa (18%)
Post-therapy: Staphylococcus aureus (30%), Enterococcus faecalis (22%)
Conclusions:
This study suggests that MDT is a viable option in patients who cannot undergo surgical wound debridement. When sterilized in egg form, larvae will secrete enzymes that increase alkaline pH levels and decrease bacterial growth. Consequentially the bacterial microflora is changed and biofilm, which normally hinders wound healing, is broken down. Based on the findings from this study, MDT provides an efficacious treatment modality for decreasing wound areas in lower extremity and foot ulcers. Although this article focuses on the changes in microflora, it is important to study the mechanisms by which larvae improve healing to maximize its utility in the future and study the rate of healing for the wounds with MDT.