In vitro antibacterial activity of mangosteen (Garcinia mangostana Linn.) crude extract against Staphylococcus pseudintermedius isolates from canine pyoderma

BackgroundStaphylococcus pseudintermedius, commonly involved in canine pyoderma, can be classified as meticillin‐susceptible S. pseudintermedius (MSSP) or meticillin‐resistant S. pseudintermedius (MRSP). MRSP infections may be difficult to treat due to broad β‐lactam resistance of MRSP and typically additional multidrug‐resistance. Topical antibacterial treatment is the preferred treatment modality for surface and superficial skin infections.Hypothesis⁄objectivesMangosteen crude extract containing the antibacterial compound α‐mangostin will have in vitro activity against MSSP and MRSP isolated from canine pyoderma.Bacterial isolatesTwenty‐three samples, MSSP (n = 12) and MRSP (n = 11), isolated from canine pyoderma.Methods and materialsMinimum inhibitory concentrations (MICs) were determined for mangosteen crude extract by broth microdilution. High‐performance liquid chromatography (HPLC) analysis was used to determine the amount of α‐mangostin in mangosteen crude extract. A time‐kill assay was performed at 30 min and 2 h after exposure to a high concentration of crude extract (100× MIC). Antibacterial activity for α‐mangostin was calculated according to HPLC results.ResultsThe concentration of α‐mangostin was 17.72 ± 1.42% w/w. The mean MIC of α‐mangostin towards MSSP was 0.53 ± 0.35 μg/mL, whereas the mean value for MRSP was 0.47 ± 0.27 μg/mL. There was no difference between the mean MIC of MRSP and MSSP (P = 0.84). After a 30 min exposure to 100× MIC of the crude extract, a 95% reduction in colony forming units was found.Conclusions and clinical importanceThe results showed that α‐mangostin in mangosteen crude extract was effective in inhibiting S. pseudintermedius (both MRSP and MSSP). Clinical studies are needed to investigate this effectiveness further in vivo.