Skin Microflora and Bacterial Infections of the Skin

Abstract

The skin is a milieu for controlled bacterial growth. Skin supports the growth of commensal bacteria, which protect the host from pathogenic bacteria. Environmental and local factors, host immunity, and organism adherence and virulence are intricately related to cutaneous infection. Resident gram-positive bacteria include Staphylococcus, Micrococcus, and Corynebacterium sp. Staphylococcus aureus and Streptococcus pyogenes are notoriously pathogenic in the skin. In order for bacteria to be pathogenic, they must be able to adhere to, grow on, and invade the host. Bacteria possess numerous virulence genes that allow for growth in these privileged niches. Epidermal infections caused by S. aureus and S. pyogenes include impetigo and ecthyma. Dermal infections consist of erysipelas, cellulitis, and necrotizing fasciitis. The pilosebaceous unit is involved in folliculitis, furunculosis, and carbunculosis. Moreover, S. aureus and S. pyogenes produce toxins that may elicit a superantigen response, causing massive release of cytokines. Staphylococcal scalded skin syndrome, toxic shock syndrome, and scarlet fever are all superantigen-mediated. Gram-negative organisms such as Pseudomonas aeruginosa, Pasteurella multocida, Capnocytophaga canimorsus, Bartonella sp., Klebsiella rhinoscleromatis, and Vibrio vulnificus are not typical resident skin microflora but may cause cutaneous infection.

Gram-positive bacteria are a major reservoir of Class 1 antibiotic resistance integrons in poultry litter

“…In the latter two genera, production of 5ЈCS-3ЈCS amplicons shows that intI1 is linked to sul1I in the hallmark arrangement of Class 1 integrons. Staphylococci and corynebacteria are common skin commensals of humans (47), and the former readily become antibiotic resistant during treatment with oral or parenteral antibiotics (48). A similar phenomenon may occur in antibiotictreated animals.…”

Rhinoscleroma: eight Peruvian cases

“…This bacterium is not a typical resident in the airway tract and the skin microbiota, so that it has been isolated only from lesions of the human airway mucosa 14 . Transmission results most probably through large amount of contaminated airborne particles, which are expelled by coughing and sneezing, or by contact with contaminated fomites 22 .…”

Detection of potentially novel bacterial components of the human skin microbiota using culture-independent molecular profiling

“…2 3 10 6 Propionibacterium granulosum Molecular profiling of skin microbiota the genus level, the detected bacteria were classified into 24 genera, which indicates a much greater diversity than that of the formerly established resident bacteria, which consists of eight genera (Chiller et al, 2001). At the species level, the detected bacteria were classified into 19 species and 13 phylotypes, which included only 10 resident bacterial species formerly identified through culture methods (Tables 2 and 3) (Chiller et al, 2001;Marples & McGinley, 1974). All 19 species and 13 phylotypes were listed according to the total number of clones detected, as seen in Table 4.…”