Commonest cause of acute folliculitis (hair follicle infection) is
Acute folliculitis are of two types: superficial and deep. The most common causative organism is Staphylococcus aureus. Superficial folliculitis is also caused by Pseudomonas aeruginosa.Reference : page 41 IADVL's Concise Textbook of Dermatology
Staphylococcus aureus
Beta hemolytic streptococcus
Propionibacterium acnes
Streptococcus viridans
Urology