Unique genetic diversity of Propionibacterium acnes isolated from human facial skins in Thailand revealed by the multi-locus sequence typing scheme

Acne vulgaris, a prevalent dermatological concern, has shown a consistent increase in reported cases from 2016 to 2019, according to data from the Institute of Dermatology, Thailand. This condition not only causes physical and psychological discomfort but also poses treatment challenges, including the potential development of antibiotic resistance. However, the precise role and distribution of Propionibacterium acnes, an acne-associated bacterium, remain unclear among the Thai population. This study aimed to investigate the prevalence of different P. acnes groups in facial samples from Thai individuals. Facial swabbing was performed to collect bacterial samples from facial skin of Thai individuals. The 16 S rRNA gene was analyzed for species identification. Multi-locus sequence typing (MLST8) was employed to classify sequence types (STs), clonal complexes (CCs), and phylotypes. Among the 65 P. acnes isolates, five closely matched sequence types (ST22, ST36, ST53, ST101, and ST115), five corresponding clonal complexes (CC1, CC2, CC3, CC5, and singleton type IA2), and three phylogroups (IA1, IA2, and IB) were identified. Notably, substantial differences were observed in the Thai samples analyzed in this study compared to findings from previous research. Specifically, CC2 (type IA2) emerged as the predominant type, in contrast to the predominance of CC1 (type IA1) reported in other studies. Furthermore, phylotype II, which has been documented elsewhere, was not detected in the present study. These variations in P. acnes prevalence highlight considerable genetic diversity across studies, potentially influenced by factors such as anatomical sampling sites and geographical regions. The isolates identified in this study will serve as valuable resources for future research on P. acnes diversity and for the development of population-specific acne treatments, particularly tailored to Thai individuals.