Evaluation of Canine Skin Infection Using ATP Bioluminescence Assay and Bactericidal Activity of Titanium Dioxide

Abstract

Quantitative measurement of the number of bacteria on the canine epidermis was done by an adenosine triphosphate (ATP) dependent chemiluminescence assay. ATP activity was measured using swab samples collected by wiping the skin of 27 dogs with pyoderma and of 15 dogs without skin problems. In the control group, the median ATP level was about half that of the dogs with pyoderma. The results indicated that a certain number of bacteria exist even on normal canine epidermis. Using the same swab samples, the numbers of bacterial colonies were counted on standard agar cultures. In the cases with pyoderma, very many colonies could be counted, whereas there were almost no colonies in the normal cases. The bactericidal activity of titanium dioxide (TiO₂) was also evaluated using the swab samples, and ATP levels were measured quantitatively by the same method. Under ultraviolet illumination, TiO₂ showed bactericidal activity against Coagulase Negative Staphylococcus that had originated from the canine skin with pyoderma, although it was almost ineffective against the viability of Malassezia or a canine malignant cell line, MCA-B1. Direct application of TiO₂ to the canine skin with pyoderma was tested clinically, and succeeded in reducing ATP levels. These results indicate that TiO₂ is potentially useful as an external medication for canine pyoderma.