Our case-control study was conducted at dermatology clinics and microbiology laboratory at Suez- Canal University Hospitals, Ismailia, Egypt to determine the microbial agents involved in the acne vulgaris, the prevalenceof P. acnes strains isolated from acne patients and healthy control groups and their antibiotic susceptibility patterns. Thirty eight acne patients (study group) were assessed according to the Acne Global Severity Scale (AGSS).The control group included 20 healthy subjects with matched age, gender and swab location of the study group. The samples were obtained by a sterile swab and then inserted into a transport medium. In the microbiology lab; microbial agents and P. acnes were isolated, identified and antibiotic susceptibility of each isolate was determined by disk diffusion method. According to AGSS,34.2% of the patients had mild acne, 42.1% had moderate acne, 15.8% had severe acne and 7.9% of them had very severe acne. The most frequent detected microorganisms in patients and controls were S. epidermidis (71.1% versus 35%, respectively), followed by P. acnes (18.4% versus 10%, respectively) and then S. aureus (10.5% versus 5%, respectively).There was significantly higher incidence of P. acnes in moderate (57.1%) and severe (28.6%) cases of acne in comparison to mild cases (14.3%) (p=0.0005). The most sensitive antibiotic was doxycycline (76.3%), followed by azithromycin (65.8%), tetracycline (60.5%), erythromycin (52.6%) and lastly clindamycin (50%). Selection of appropriate antibiotics is highly important in order to decrease antibiotic resistance rates and treatment failure.