Staphylococci: Colonizers and Pathogens of Human Skin

Rosanna Coates; Josephine Moran; Malcolm J Horsburgh

Disclosures

Future Microbiol. 2014;9(1):75-91. 

In This Article

Abstract and Introduction

Abstract

Staphylococci are abundant bacteria of the human skin microbiome. Several species, particularly Staphylococcus aureus and Staphylococcus epidermidis, are opportunistic pathogens and cause significant disease. The human skin serves many functions and here we review its role as an antimicrobial barrier and the staphylococcal mechanisms to colonize and counteract the various stresses present in this niche. Successful colonization is achieved using a diversity of adhesins, surface proteins and secreted enzymes to counteract the antimicrobial peptides, enzymes and lipid matrix components present in the acid mantle. Further mechanisms enable these bacteria to overcome osmotic and acid stresses and desiccation in order to survive the exacting demands of an ever-changing landscape.

Introduction

The skin is a vital barrier against infection with many defenses to prevent invasion, yet many organisms thrive within this hostile environment. Resident bacteria of the skin microbiome, including certain species of staphylococci, supplement the barrier function of the epidermis by inhibiting the colonization of skin pathogens such as Staphylococcus aureus through nutrient competition and the production of antimicrobial peptides (AMPs).[1] The importance of the human microbiome in health and disease is increasingly being recognized and is driving efforts to model the community structure of the resident microbiota.[2–5] Such studies highlight the diversity of the resident skin community across the human body over time, between individuals and ages.[3,6–9]

Staphylococci are the most studied of the resident skin flora owing to their ubiquitous colonization of human skin and the wide spectrum of diseases they cause. The dominant Staphylococcus species on skin is S. epidermidis, which is considered to be a universal colonizer and part of a pan-microbiota.[10] Across different body sites a substantial proportion of the skin community comprises coagulase-negative staphylococci (CoNS), including S. hominis, S. haemolyticus, S. saprophyticus, S. capitis, S. warneri, S. simulans and S. cohnii. Coagulase-positive S. aureus is not considered to be part of the natural skin microbiota and nasal decolonization treatments reduce its frequency on skin.[11,12] While most CoNS interactions with skin are likely to be commensal, they can cause opportunistic infections.[13] Staphylococcal diseases range from common skin ailments, such as boils and impetigo, to urinary tract infections and more serious diseases, including postsurgical infections, device-associated disease, toxic shock syndrome and systemic infection.[14]S. aureus colonization has been linked as a risk factor of certain infections, such as bacteremia.[15]

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