RESUMEN
This study aims to present the in vitro inhibitory effect of Psidium guajava and Juglans regia leaf extracts on the main developer of acne lesions, Propionibacterium acnes (P. acnes), and other organisms that are isolated from acne lesions. Thirty-eight subjects (males and females) who had various types of acne were enrolled in the study. The contents of the acne lesions were cultured and the frequency of P. acnes (alone and with Staphylococci spp.) was 47%, whereas the frequencies for Staphylococcus aureus and Staphylococcus epidermidis were 13% and 24%, respectively. The antimicrobial activities of Psidium guajava and Juglans regia leaf extracts, determined by disk diffusion method (zone of inhibition), were compared to tea tree oil (TTO), doxycycline and clindamycin antibiotics. The zones of inhibition due to the Psidium guajava and Juglans regia leaf extracts ranged from 15.8-17.6 mm against P. acnes, 11.3-15.7 mm against S. aureus and 12.9-15.5 mm against S. epidermidis, respectively. These zones of inhibition were significantly higher than those of TTO and equivalent in case of Staphylococci spp., but less in case of P. acnes, to those obtained from doxycycline or clindamycin. It can be concluded that Psidium guajava and Juglans regia leaf extracts may be beneficial in treating acne especially when they are known to have anti-inflammatory activities.