Evaluation of Methylene Blue as An Effective Antiseptic for Medicinal Leeches
Doğan S, Farzali S, Karimova B, Sağlam N (2024) · Türkiye Parazitoloji Dergisi · n=570
Study Profile
- Design
- in-vitro dose-finding study of methylene blue as an antiseptic for medicinal leeches; 570 Hirudo medicinalis specimens (Turkish leech farm, Fırat University) tested across 18 concentrations (1-512 ppm)
- Sample size (n)
- 570
- Intervention
- Methylene blue antiseptic baths at concentrations ranging 1-512 ppm to determine safe and effective antiseptic concentrations for medicinal-leech husbandry
- Comparator
- Saline-only control bath; not a comparison to other antiseptics in this study
- Primary endpoint
- Lethal concentration 50% (LC50), effective concentration (EC), and lethal time 50% (LT50) for medicinal leeches
- Primary result
- LC50 = 60.4 ppm (95% CI 53.7-66.6); EC = 2.0 ppm (95% CI 1.8-2.2); LT50 = 213h at 32 ppm vs 18h at 512 ppm; authors conclude MB concentrations of 2-19 ppm are safe and effective for hirudotherapy clinic and leech-farm antisepsis
- Follow-up duration
- Up to 1486 hours (LT50 upper CI at 32 ppm)
- PMID
- 38958415
Key Findings
- First systematic dose-finding study of methylene blue antisepsis for medicinal leeches
- Wide safety margin: EC50 (2 ppm) vs LC50 (60 ppm) — 30-fold therapeutic index
- Practical operating range 2-19 ppm fits with existing aquaculture infrastructure
- Provides leech-farm and hirudotherapy-clinic husbandry guidance
- Indirectly relevant to patient safety via reduced bacterial bioburden on therapy leeches
Limitations
- In-vitro / aquaculture model — does not measure clinical infection outcomes
- Single species (Hirudo medicinalis) — generalizability to Hirudinaria or Whitmania unclear
- Did not test methylene blue against specific pathogens (Aeromonas, Vibrio)
- Long LT50 confidence intervals at low concentrations limit precision
- Methylene blue residue on leech epidermis during patient application not characterized
Clinical Implications
Doğan 2024 provides actionable husbandry guidance for medicinal-leech farms and hirudotherapy clinics seeking to reduce gut-bacterial bioburden on therapy-grade leeches. For US K040187 hirudotherapy programs, the data inform potential pre-application leech-cleansing protocols but do not change patient-level antibiotic prophylaxis recommendations (still anchored on Aeromonas-active agents per Wilmer 2013, Beka 2018, Kruer 2014). The study complements Karasartova 2025 (leech microbiota and infection risk) by offering a candidate husbandry intervention.
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