Kali carbonicum 6cH controls Malassezia pachydermatis growth in vitro

Abstract

External otitis caused by Malassezia pachydermatis is a common disease in the veterinary practice routine, whose treatment has been challenging due to the risk of antimicrobial resistance. Thus, Homeopathy is seen as a possible alternative to control the infection. To screen potential medicines to be used in a non-individualized clinical homeopathy approach, a series of in vitro assays were performed, in which a suspension of M. pachydermatis colonies in 0.5 McFarland scale was diluted 1:1000 in sterile saline solution, and 10 µL of pre-selected homeopathic medicines was added. Sulphur 6cH, Dolichos pruriens 6cH, and Kali carbonicum 6cH were chosen from a pilot study, and the last potency was prepared in pure, sterile water. The controls were pure, sterile water and succussed pure, sterile water. An amount of 50 µL of each suspension has seemed in plates containing Sabouraud dextrose agar medium, with or without 1% Tween 80, for counting of colony-forming units (CFU) and cytomorphological analysis of M. pachydermatis samples taken from the same colonies. The analysis was made using Image J 1.53 by manually counting quiescent and germinative forms. Kali carbonicum 6cH treatment decreased the germinative/quiescent ratio in relation to the controls, independent of Tween 80 presence in the medium. The UFC counting, however, did not show statistically significant differences among groups, probably by the lack of cytotoxicity against the yeasts. In conclusion, Kali carbonicum 6cH was considered a promising medicine to be tested in clinical conditions, probably due to its capacity to control yeast growth without creating a selective pressure able to induce resistance mechanisms.