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Summer 2014, Vol. 22 No. 2

Hong Kong J. Dermatol. Venereol. (2014) 22, 57-64


Original Article

Effect of pH on fungal growth: problems with using vinegar (5% acetic acid) in treating superficial fungal infections

酸鹼值對真菌生長的影響:用醋(5%醋酸)治療表層真菌感染所面對的問題

YY Cheung 張煜鑫, SHC Lee 李孝治, M Hui 許明媚, TNM Luk 陸乃明

Abstract

Objectives: To investigate the effect of different pH on the in vitro growth of Trichophyton rubrum (T. rubrum) and to study the pH achievable by a test product at various depths in a porcine nail model. Methods: T. rubrum was grown in Sabouraud dextrose broth of various acidic pH to determine the fungicidal level. A test product with active ingredient of acetic acid was applied to the porcine nails for 60 and 120 times and the pH at various depths of penetration was measured by pH metre. Results: A pH of 3.0 or below is fungicidal to T. rubrum and the minimal pH achievable by 60 and 120 applications of the test product were 4.09 and 3.37 respectively. Conclusions: Use of vinegar (5% acetic acid) to treat tinea pedis is theoretically efficacious but it is difficult to achieve a fungicidal pH of 3.0 at the nail bed despite prolonged application.

目的:研究不同酸鹼值對活體外紅色毛癬菌生長的效果,並檢測所測試產品在豬蹄甲模型的不同深度可達致的酸鹼值。方法:在不同酸鹼值的薩氏葡萄糖瓊脂培養基內培養紅色毛癬菌,以確定殺真菌的酸鹼水平。另將一種內含醋酸活性成份的測試產物分別塗於豬蹄甲各60和120次,然後用酸鹼度計探測不同深度滲透所達致的酸鹼值。結果:紅色毛癬菌的殺真菌酸鹼值水平為3.0或以下,而該測試產品在60和120次塗抹後可達致的最低酸鹼值分別為4.09和3.37。結論:使用醋(5%醋酸)來治療足癬,在理論上是可行的;但即使長時間應用,它亦難以在甲床達致3.0的殺菌酸鹼值水平。

Keywords: Acetic acid, pH, superficial fungal infections, T. rubrum, vinegar

關鍵詞: 醋酸、酸鹼值、表層真菌感染、紅色毛癬菌、醋