Antibacterial activity of cannabis extract (Cannabis sativa L. subsp. indica (Lam.)) against canine skin infection bacterium Staphylococcus pseudintermedius

Superficial bacterial skin infections caused by Staphylococcus pseudintermedius are common in dogs. The cannabis plant has shown potential antibacterial effects, but there is limited information about anti-S. pseudintermedius activity. This study investigated the antibacterial activity of the ethanolic extract and the topical formulations of Cannabis sativa L. subsp. indica (Lam.) against 23 S. pseudintermedius isolates obtained from canine pyoderma using broth microdilution and time-kill assays. The cannabis extract's minimum inhibitory concentrations for 50% (MIC50) and 90% (MIC90) of the tested S. pseudintermedius isolates were 6.25 and 12.50 mu g/ml, respectively. The MIC for S. pseudintermedius ATCC 49051 was 6.25 mu g/ml. The time-kill test revealed that the bactericidal effect of the cannabis extract was time- and not concentration-dependent. Topical formulations containing 0.5, 1, 2, 5, and 10% w/w cannabis extract showed limited in vitro antimicrobial activity in the time-kill test. Only the formulations with cannabis extract of 10% and 5% w/w could reduce the number of viable S. pseudintermedius ATCC 49051 by more than 3-log(10) (99.9%) at 6 and 24 h, respectively. This study demonstrated that the cannabis extract has a good potential to be developed as an antibacterial agent against S. pseudintermedius. However, a clinical trial should be conducted to determine its in vivo therapeutic efficacy.