In vitro antibacterial activity and in vivo efficacy of hydrated clays on Mycobacterium ulcerans growth

Abstract

BackgroundBuruli ulcer, caused by Mycobacterium ulcerans, is a localized skin lesion that can progress to extensive ulceration and necrosis if left untreated. Unpublished studies of hydrated clays for therapeutic, topical treatment of Buruli ulcer suggest that specific clay mineral products may have beneficial effects on wound healing. In this study, we evaluated the in vitro antibacterial activity of a panel of clay mixtures and their derivative leachates against M. ulcerans and assessed the in vivo efficacy of topically-applied, hydrated clays on Buruli ulcer progression in mice infected with M. ulcerans. Methods M. ulcerans 1615 was incubated with 10 % suspensions of CB07, CB08, CB09, CB10, and BY07 clay mixtures, and survival was determined over 28 days. For animal experiments, we examined the effect of topical hydrated clay therapy on Buruli ulcer progression in vivo in mouse tails subcutaneously infected with M. ulcerans 1615. ResultsThe CB07, CB08, and CB09 clays exhibited bactericidal activity against M. ulcerans after 7, 14, 21, and 28 days of incubation. In contrast, clay leachates exhibited inhibitory, bacteriostatic effects on M. ulcerans growth in vitro. After establishing an ulcerative M. ulcerans infection for three months, ulcerated regions of the tails were treated once daily (five consecutive days per week) for 22 days with hydrated CB09 clay poultices. Mice in the clay treatment group exhibited healing as assessed by gross morphological changes and a reduction in M. ulcerans present in the wounds.ConclusionsThese data reveal that specific clays exhibit in vitro bactericidal activity against M. ulcerans and that hydrated clay poultices may offer a complementary and integrative strategy for topically treating Buruli ulcer disease.

Traditional knowledge and practice of the Triassic variegated clay from Silesia (Krasiejów), Poland, in human medicine

“…As 94.34% analyzed questionnaires were consistent, this study extends existing scientific knowledge on the therapeutic use of clays, as Krasiejów clay was used with additional disease units before it was known (compare e.g., [ 2 , 5 , 7 , 8 , 10 , 11 , 14 , 19 , 20 , 24 ]). Namely, to date, the clays were used mainly as antibacterial agents, especially in the case of antibiotic resistance.…”

“…In traditional human medicine, the clay has been used both externally and internally, for instance, as an aseptic, astringent, and absorbing agent. Recently, however, there has been an increased interest in the geochemical properties of these minerals with respect to antibacterial and anti-inflammatory actions [ 2 , 8 , 19 – 23 ]. The emergence of antibiotic-resistant bacteria has accelerated the search for new sources of antibacterial compounds.…”

Buruli Ulcer in Animals and Experimental Infection Models

“…On a few occasions, treatment alternatives to drug administration were also tested in the BU mouse model: The effect of corticosteroid-induced immunosuppression on therapy with antibiotics was examined [83], phage therapy was shown to be effective in mice [54] and even the efficacy of hydrated clays on M. ulcerans growth was assessed in vivo on mouse tails [84]. However, as ideal the mouse model might be for drug testing and every therapy that can be applied by injection or orally, for the evaluation of topically applied therapies, including thermotherapy, the mouse model is highly impractical.…”

The Use of Medicinal Clay from Silesia “Terra sigillata Silesiaca”, Central Europe - A New Chance for Natural Medicine?

“…Caspar Schwenckfeld (1563-1609) was a spa doctor from Cieplice, Silesia, and a botanist, mineralogist, zoologist, and natural historian of the Karkonosze region, regarded as one of the outstanding Silesian scientists of the Renaissance, who also mentioned "terra sigillata Silesiaca" in his monograph "Stirpium & Fossilium Silesiae Catalogus" [10]. The therapeutic use of clay (terra sigillata medicorum) by potters in human and pet animals was known until the 19 th century in places of different cultures or religions around the world [11][12][13][14][15][16]. At the end of the 19 th century, Sebastian Kneipp (1821-1897), a creator of prophylactics and treatments who practiced in Bavaria, described in the List of Intangible Cultural Heritage of Humanity of UNESCO in 2015 treatment with clay compresses for ulceration, slow-healing cuts or stab wounds, and insect bites [17].…”