Antimicrobials and the skin physiological and pathological flora

Area of Science:

• Microbiology
• Dermatology
• Human Microbiome

Background:

• Healthy human skin is naturally colonized by various microorganisms.
• Key resident bacteria include coagulase-negative staphylococci, diphtheroid rods, and propionibacteria.
• Fungi such as Pityrosporum (Malassezia spp.) are also commonly found on the skin.

Purpose of the Study:

• To describe the composition and factors influencing the skin's resident microflora.
• To investigate the effects of antimicrobials on the skin's microbial ecology.
• To assess the potential for antimicrobial use to lead to pathogenic bacterial overgrowth.

Main Methods:

• Isolation and identification of bacterial and fungal genera from human skin.
• Analysis of factors influencing flora distribution and density (age, sebum, environment).
• Review of antimicrobial effects on resident flora and potential ecological shifts.

Main Results:

• Skin flora composition varies with age and environmental factors like sebum, temperature, and humidity.
• Axillary odor is linked to aerobic diphtheroid activity.
• Antimicrobials reduce but do not eradicate resident flora and can cause contact dermatitis.
• No evidence supports antimicrobials altering skin ecology to promote pathogenic bacterial overgrowth.

Conclusions:

• The skin's resident microflora is dynamic and influenced by host and environmental factors.
• Antimicrobial use may impact flora density and cause dermatitis but does not appear to disrupt the ecological balance leading to pathogenic overgrowth.