Anti-microbial Role of Non-antibiotic Agents Against Cutibacterium Acnes in Patients With Acne Vulgaris

Primary outcomes

1. inhibition of biofilm formation of c.acne after the use of Salicylic acid, Isotretinoin, and N-acetylcysteine

   Time frame: 6 month

   Biofilm forming ability of P. acnes isolates was adapted from Coenye et al., 2007 and Abbott et al., 2022

   G. The results were obtained according to (Stepanovic et al., 2007); the average OD values were calculated for all tested isolates & negative controls, and the cut-off value (ODc) was detected. It is defined as a 3 standard deviation (SD) above the mean OD of the negative control. The final OD value of a tested strain was expressed as the average OD value of the strain reduced by ODc value; ODc value was calculated for each plate separately. For easier interpretation of the results, strains were divided into the following categories:

   • Non-biofilm producer = OD ≤ODc
   • Strong biofilm producer = 4×ODc <OD

   Growth in the presence of the following agents was tested (all percentages are w/v): 2% salicylic acid, 5% acetylcysteine, and 0.05% isotretinoin

2. improvement of antibiotic sensitivity of c.acne after the use of Salicylic acid, Isotretinoin, and N-acetylcysteine

   Time frame: 6 month

   All strains were tested for antibiotic susceptibility to azithromycin and doxycycline The minimal inhibitory concentration (MIC) was evaluated by the broth microdilution method according to CLSI (2012). The minimal bactericidal concentration (MBC) was evaluated by using a modified flash microbicide method (Hernandes et al., 2013).

   The MICs of the tested antimicrobial agents were determined by the broth microdilution method according to CLSI (2012) as above in the presence of 2% salicylic acid, 5% acetylcysteine and 0.05% isotretinoin