Acne Treatment with Topical Antibiotics

Pathogenesis of inflammation

P. acnes is found in low numbers on normal skin and is probably not

infectious. The bacteria may be the primary factor in the production of

inflammatory acne. The mixture of abnormally desquamated cells and

excessive amounts of sebum in the microcomedo provides a lipid rich

environment for bacteria to thrive. They produce neutrophil chemotactic

factors and stimulate neutrophils to release lysosomal enzymes. These

proinflammatory mediators attack the microcomedo follicular wall and

contribute to the formation of inflammatory lesions. Acne improves

when the P. acnes numbers are reduced. P. acnes is sensitive to many

antibiotics. The problem is to deliver antibiotics into the lipid-rich

environment of the sebaceous follicles where the organism is

proliferating. Topical and oral antibiotics are used alone or in

combination with topical retinoids. Retinoids disrupt the microcomedo.

Benzoyl peroxide

Benzoyl peroxide is an effective non-specific antimicrobial agent. It

penetrates sebum and suppresses the growth of P. acnes more effectively than topical clindamycin and erythromycin. It has only a weak effect on inflammation and little comedolytic activity. It does not stimulate bacterial resistance like erythromycin and clindamycin. Product formulations include gels, creams, lotions, cleansers and bar soaps. It is available in available in 2.5, 4, 5, 6, 8, 9 and 10 percent

formulations. Sulfoxyl strong and Sulfoxyl regular are 10 and 5

percent formulations of benzoyl peroxide that contain sulfur. They are

antibacterial and keratolytic and can be very effective for patients

with pustular acne and oily skin.

PB causes concentration-dependent irritation, erythema and dryness. It

has the potential to cause allergic contact dermatitis. Suspect this

side effect when patients complain of the acute onset of erythema and

itching at a higher intensity that would be expected from just

irritation from the base. Benzoyl peroxide can bleach clothing.

Benzoyl peroxide/clindamycin

Benzoyl peroxide is available as a 5 percent gel in combination with

erythromycin called Benzamycin. There are two benzoyl peroxide

clindamycin combination products. Benzaclin is available in a jar.

Duac is available in a tube. These combination products result in

greater reductions in inflammatory lesions and comedones at 16 weeks when compared to monotherapy with clindamycin. BP helps to reduce the emergence to resistant variants of P. acnes.

Clindamycin

Clindamycin is effective as monotheryapy for short periods of

treatment. Products include solution, lotions, gels and pledgets. It

can be especially effective when used as combination therapy with

retinoids such as tretinoin, tazarotene, and adapalene. If use for

longer than 3 months is required than switch to a combination benzoyl

peroxide/clindamycin product to avoid the problems of bacterial

resistance to clindamycin.

Sodium sulfacetamide and sulfur

These combination products have been available for many years. They

have antimicrobial activity and are keratolytic. They inhibit comedogenesis by normalizing desquamation of the follicular epithelium. They may cause irritation. Recently may gel, cream and cleanser formulations have become available. Klaron lotion is pure

sulfacetamide and is less irritating.

Azelaic acid

Topical Azelaic acid has been available in Europe for years. It reduce

P. acnes to about the same degree as topical clindamycin. It has mild

comedolytic and antiinflammatory activity. It also suppresses

post-inflammatory hyperpigmentation that is a problem in patients with

a dark complexion.