title: In-vivo Effectiveness of Adapalene 0.1%/Benzoyl Peroxide 2.5% Gel on Antibiotic-sensitive and Resistant Propionibacterium acnes.
abstract: BACKGROUND
  A gel combination treatment containing a retinoid (adapalene 0.1%) and an antimicrobial (benzoyl peroxide 2.5%) has been shown to be an effective treatment for acne vulgaris, addressing three of the four pathogenic factors (hyperkeratinization, Propionibacterium acnes proliferation, inflammation) without contributing to the incidence of Propionibacterium acnes antibiotic resistance as neither the retinoid nor benzoyl peroxide creates selective pressure for resistance.
  
  
  OBJECTIVE
  To evaluate the effectiveness of an adapalene-benzoyl peroxide gel combination in reducing antibiotic-sensitive and resistant strains of Propionibacterium acnes on the facial skin of volunteers.
  
  
  METHODS
  This four-week, open-label, single-center study included 30 healthy adults with high facial Propionibacterium acnes populations [>10(4) colony-forming units per square centimeter of skin (CFU/cm(2))] and presence of subpopulations resistant to erythromycin, tetracycline, and clindamycin. The gel was applied once daily to the forehead. Cultures for total and antibiotic-resistant Propionibacterium acnes were obtained from the forehead area at screening, Baseline, Week 2, and Week 4.
  
  
  RESULTS
  Total Propionibacterium acnes counts decreased by 1.1 log(10) CFU/cm(2) after two weeks of treatment, and by 1.6 log10 CFU/cm(2) after four weeks. All subjects had strains resistant to each of the five antibiotics at baseline. Mean counts of erythromycin and clindamycin resistant Propionibacterium acnes were high at baseline (5.37 and 5.28 log(10) CFU/cm(2), respectively) and decreased by ≥2.1 log(10) by Week 4 (P<0.001). Mean counts of strains resistant to tetracyclines were lower at baseline (3.8 to 4.2 CFU/cm(2)) and decreased by 1.9 (tetracycline), 2.4 (minocycline), and 1.3 (doxycycline) log(10) CFU/cm(2) by Week 4 (P<0.001).
  
  
  CONCLUSIONS
  Although limited in scope, the results of the present study demonstrate that the fixed-dose combination gel containing adapalene 0.1% and benzoyl peroxide 2.5% effectively inhibited both antibiotic-susceptible and antibiotic-resistant Propionibacterium acnes. In addition to reducing population densities, therapy with adapalene-benzoyl peroxide eradicated some resistant strains entirely in some individual subjects.
  
  
  CONCLUSIONS
  Topical adapalene-benzoyl peroxide gel effectively reduced skin colonization by antibiotic-sensitive and antibiotic-resistant Propionibacterium acnes after four weeks. This trial was registered with ClinicalTrials.gov (http://clinicaltrials.gov/), registry number NCT00907101.
authors: James J
authors: JJ
authors: Leyden
authors: Norman
authors: N
authors: Preston
authors: Cris
authors: C
authors: Osborn
authors: Ronald W
authors: RW
authors: Gottschalk
references: Eur J Dermatol. 2004 Jan-Feb;14(1):4-12
references: 14965788
references: Skin Pharmacol Physiol. 2006;19(5):283-9
references: 16778460
references: J Invest Dermatol. 1965 Dec;45(6):498-503
references: 5321315
references: Med J Aust. 1998 Sep 7;169(5):259-61
references: 9762064
references: Br J Dermatol. 1995 Feb;132(2):204-8
references: 7888356
references: Drugs. 1997 Mar;53(3):511-9
references: 9074847
references: BMJ. 2002 Aug 31;325(7362):475-9
references: 12202330
references: Infect Disord Drug Targets. 2008 Sep;8(3):156-9
references: 18782032
references: Dermatology. 1998;196(1):119-25
references: 9557245
references: Cutis. 2008 Nov;82(5):336-42
references: 19090337
references: Br J Dermatol. 2009 Nov;161(5):1180-9
references: 19466959
references: J Am Acad Dermatol. 2009 May;60(5 Suppl):S1-50
references: 19376456
references: Br J Dermatol. 2002 May;146(5):840-8
references: 12000382
references: Cutis. 2007 Jul;80(1 Suppl):5-9
references: 17824580
references: Arch Dermatol Res. 1979 May 4;264(3):369-71
references: 464656
references: Clin Ther. 2002 Jul;24(7):1117-33
references: 12182256
references: Ann Acad Med Singap. 2001 Jan;30(1):22-5
references: 11242619
references: J Cutan Pathol. 1974;1(5):191-200
references: 4283462
references: Arch Dermatol. 1983 Jul;119(7):577-9
references: 6222704
references: Br J Dermatol. 2003 Mar;148(3):467-78
references: 12653738
references: J Am Acad Dermatol. 1983 Jan;8(1):41-5
references: 6219134
references: Br J Dermatol. 1989 Jul;121(1):51-7
references: 2527056
references: J Am Acad Dermatol. 2003 Jul;49(1 Suppl):S1-37
references: 12833004
references: Br J Dermatol. 2001 Feb;144(2):339-46
references: 11251569
references: Adv Ther. 2002 May-Jun;19(3):109-18
references: 12201351
references: Dermatol Clin. 2009 Jan;27(1):1-15
references: 18984363
references: Br J Dermatol. 1998 Oct;139 Suppl 52:3-7
references: 9990413
references: Am J Clin Dermatol. 2001;2(4):263-6
references: 11705253
references: Dermatol Clin. 2009 Jan;27(1):17-24
references: 18984364
references: J Dermatolog Treat. 2002 Sep;13(3):107-10
references: 12227872
references: Eur J Dermatol. 2001 Nov-Dec;11(6):549-53
references: 11701406
references: Lancet. 2004 Dec 18-31;364(9452):2188-95
references: 15610805
references: Cutis. 2008 Dec;82(6):417-21
references: 19181031
references: J Clin Microbiol. 1990 May;28(5):941-3
references: 2191014
references: J Am Acad Dermatol. 1997 Jun;36(6 Pt 2):S96-103
references: 9204085
references: Cutis. 2009 Aug;84(2):110-6
references: 19746769
references: Int J Dermatol. 2003 Dec;42(12):925-7
references: 14636182
references: J Am Acad Dermatol. 1999 Nov;41(5 Pt 1):710-6
references: 10534632
references: J Drugs Dermatol. 2009 Jul;8(7):657-61
references: 19588642
references: J Am Acad Dermatol. 2007 Nov;57(5):791-9
references: 17655969