Abstract: The present disclosure relates to method for detecting P. acnes as well as a method for detecting mutation in genomic sequence of 23S rRNA sequence of P. acnes, particularly mutation A2058G. The method comprises amplifying a region of 23S rRNA specific for P. acnes using primers of SEQ ID Nos. 1 and 2 followed by detecting the mutation through selective action of an endonuclease- at a mismatch at the site of said mutation or post-hybridization with specific P. acnes 23S regions followed by mismatch specific endonuclease action. The presence of A2058G mutation confers antibiotic resistance, particularly clindamycin and erythromycin resistance, and thus the present disclosure also relates to methods of treating acne caused by clindamycin resistant P. acnes by using fluoroquinolone based antibiotics.