The microbiology  of normal  follicles, acne-affected follicles  and Pityrosporum  folliculitis is  similar  and limited  to  a  narrow range  of micro-organisms, these being propionibacteria, staphylococci and M. furfur. This observation has made it difficult to assign a role to these micro-organisms in the two diseases. The mass of circumstantial evidence incriminates P. acnes in inflammatory  acne and M. furfur in folliculitis. In the case of acne, the extent of P. acnes involvement is still under investigation as well  as  the  specific mechanism by which it exerts its detrimental affects.

 

  Gram-negative folliculitis, in comparison, has irrefutable evidence proving that some Gram-negative bacteria not found in normal follicules or on glabrous skin are present in these pathologically  affected follicles, and with specific treatment to eliminate these bacteria, there is clinical efficacy.

 

  Many methods have been devised to sample and study cutaneous microflora, and these include swabbing, scrubbing, use of adhesives and biopsy. Of these only biopsy followed by  microbiological analysis is adequate to define the microflora of follicles.