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REVIEW 277 ▲ Pyodermitis * Piodermites Júlio César Empinotti 1 Hirofumi Uyeda 2 Roseli Terezinha Ruaro 3 Ana Paula Galhardo 4 Danielle Cristine Bonatto 4 Abstract: Pyodermitis are primary skin infections mainly caused by pyogenic bacteria of the Staphylococcus and Streptococcus genera. They are relatively common diseases that affect adults and children. There have been fre- quent reports of bacterial resistance to the recommended antibiotics over the last few years; however, new subs- tances are in use or under development, and this represents an evolution in the treatment of pyodermitis. This review aims at describing clinical, diagnostic and therapeutical features of major pyodermitis: impetigo, ecthyma, erysipelas, staphylococcal scalded skin syndrome and folliculitis. Keywords: Bacterial infections; Review; Staphylococcus; Streptococcus; Skin infections staphylococcal Resumo: As piodermites são infecções cutâneas primárias originadas principalmente por bactérias piogênicas dos gêneros Staphylococcus e Streptococcus. Tratam-se de doenças relativamente comuns, que acometem adul- tos e crianças. Nos últimos anos há relatos freqüentes de resistência bacteriana aos antibióticos preconizados, no entanto, novas substâncias estão em uso ou mesmo em desenvolvimento, o que representa uma evolução na terapia das piodermites. Esta revisão tem como objetivo descrever aspectos clínicos, diagnósticos e terapêuticos das principais Piodermites: impetigo, ectima, erisipela, síndrome da pele escaldada estafilocócica e foliculites. Palavras-chave: Infecções bacterianas; Infecções cutâneas estafilocócicas; Revisão; Staphylococcus; Streptococcus INTRODUCTION The skin has resident bacteria, which live as Staphylococcus aureus (coagulase- positive) and by commensal bacteria, and transient bacteria, which can Streptococcus pyogenes. These bacteria, originating occasionally colonize the skin. The resident flora con- from the environment, show pathogenicity usually in sists mainly of Gram-positive cocci (Staphylococcus the presence of a disturbance of skin integrity. 1 epidermidis), diphtheroids (Corynebacterium and Pyodermitis are defined as primary skin infec- Brevibacterium) and anaerobic rods (Propioni - tions caused mainly by pyogenic bacteria of the bacterium). The organisms of the resident flora contri- Staphylococcus and Streptococcus genera. 3 bute to resistance against colonization with pathoge- Among staphylococci, Staphylococcus aureus nic bacteria by hydrolyzing lipids and producing free (S. aureus) is the most important pathogen, causing fatty acids, which are toxic to many bacteria. 1,2 superficial or deep infections and diseases related to The transient flora is mainly represented by the action of their toxins. The skin is the natural habi- Received on 19.04.2011. Approved by the Advisory Board and accepted for publication on 13.07.2011. * Work conducted at Universidade Estadual do Oeste do Paraná - UNIOESTE, Cascavel Parana, Brazil. Conflict of interest: None Financial Support: None 1 PhD – Professor of Dermatology, Universidade Estadual do Oeste do Paraná - UNIOESTE - Cascavel (PR), Brazil. 2 Dermatologist, Associate Member of the Brazilian Society of Dermatology - Assistant Professor of Medicine, Universidade Estadual do Oeste do Paraná - UNIOESTE - Cascavel (PR), Brazil. 3 Dermatologist, Associate Member of the Brazilian Society of Dermatology - Collaborator Professor of Dermatology, Medical School, Universidade Estadual do Oeste do Paraná - UNIOESTE - Cascavel (PR), Brazil. 4 Medical Student, Universidade Estadual do Oeste do Paraná - UNIOESTE - Cascavel (PR), Brazil. ©2012 by Anais Brasileiros de Dermatologia An Bras Dermatol. 2012;87(2):277-84. 278 Empinotti JC, Uyeda H, Ruaro RT, Galhardo AP, Bonatto DC tat of many species of staphylococci. There is perma- Impetigo nent colonization with S. aureus in the anterior nares Impetigo is a superficial skin infection caused of 20% of the population. Approximately 60% of healt- mainly by staphylococci and, less often, streptococci hy individuals have occasional colonization with S. or a combination of both bacteria. The disease is com- aureus somewhere in the body, especially in the axil- mon and more prevalent in children. 1 (Figure 1). la, perineum, pharynx, hands and nares. The main There are two variants of the disease: nonbul- defense against staphylococci is neutrophil phagocy- lous impetigo and bullous impetigo. Staphylococci tosis. Conditions that predispose to skin colonization have been the cause of bullous impetigo and group A due to low resistance to the agent include atopic der- streptococci are most frequently the causative orga- matitis, diabetes mellitus, dialysis, intravenous drug nisms in nonbullous impetigo. 3 use, liver dysfunction and HIV infection. Direct inva- The nonbullous variant, which accounts for sion occurring at small breaks in the mucous membra- more than 70% of cases, also known as impetigo con- nes, skin and its appendages results in a variety of tagiosa (Tilbury-Fox), begins with a thin-walled vesicle superficial infections. 1,4,5 or pustule, hardly noticeable, as it soon ruptures, Streptococci almost always participate in the sometimes on an erythematous base. The purulent microbiota of the oral or gastrointestinal tract, and exudate dries and forms the classic thick yellow- they are among the most common agents of human brown crust (meliceric). When removed, the crust diseases. Streptococcus pyogenes (S. pyogenes) is res- quickly reappears. Although exposed areas of skin are ponsible for most infections caused by bacteria of the affected more often in adults, in children any site can Streptococcaceae family, being found in the oropha- be affected. 6,7 rynx of 10% of the general population. Only 1% of In staphylococcal bullous impetigo, small individuals have it in normal skin. The most virulent breaks in the skin allow the onset of infection with the streptococci belong to group A and have the M pro- formation of blisters caused by staphylococcal exfolia- tein on their surface, which protects against phagocy- tive toxins produced on site. The disease affects chil- tosis and increases adherence to epithelial tissues. 1 dren, most often in the face and legs; however, it can Infections with S. pyogenes are more common in also involve other areas. 4 Lesions begin as erythema- childhood and adolescence. This is due to the fact that tous maculae that progress to superficial blisters with successive infections, symptomatic or unapparent, serous content. Nikolsky’s sign is not present. 1 These with prevalent serotypes in the community confer las- blisters rupture easily, leading to the formation of ting and specific immunity against this pathogen. 4 thin, smooth, honey-colored crusts, similar to a coa- The frequency of pyodermitis varies based on ting film, which, upon scaling, do not leave scars. The several factors; in general, they affect around 7% of lesions are small, multiple and in various stages of the population. The summer season favors skin infec- development. Staphylococcal bullous impetigo does tions, as it facilitates the installation and maintenance not jeopardize the general health of the individual, of the microclimate, heat and moisture necessary for and fever is only present when there are multiple the development of infectious agents. 5 lesions. Locally, there is minor discomfort and itching In the pathogenesis of pyodermitis we must may occur. 4 consider host factors: presence of resident flora which hinders the colonization with other bacteria and pro- duces unsaturated fatty acids that form a chemical bar- rier; mechanical barrier; the moisture content of the skin - the higher the moisture, the easier the bacterial multiplication; an alkaline pH that facilitates bacterial colonization, and the immune competence of the individual. With regard to the microorganism, the degree of pathogenicity and virulence is considered, which basically derives from the invasive potential determined by the presence of antiphagocytic ele- ments on the bacterial surface and the ability to pro- duce toxins. Although the etiology of pyodermitis is basical- ly the same, there are several distinct clinical forms with regard to morphology, evolution, pathogenesis, 5 complications and therapy. FIGURE 1: Impetigo An Bras Dermatol. 2012;87(2):277-84. Pyodermitis 279 In the two variants, after the vesiculobulla rup- low sensitizing power, such as mupirocin or fusidic tures and there is crust formation, central clearing acid. This approach is sufficient to clear mild to mode- and peripheral extension can lead to a circinate rate cases, since the infection is often self-limited. 3,7 lesion, mimicking superficial fungal infection. Lesions Recently, retapamulin has been revealed as a are usually asymptomatic and may sometimes show new topical antibiotic to treat cases of impetigo. mild itching or burning. There is rapid development Retapamulin is the first member of a new class of anti- of satellite lesions by contamination of other areas, by biotics called pleuromutilins. It is a semi-synthetic scratching, or where there was contact with the exu- drug, available as 1% ointment for dermatological use date. 6 only. It was approved by the FDA in April 2007 for the The appearance of lesions of impetigo, which treatment of impetigo, when the disease is caused by usually follows bruising, abrasions, minor trauma or S. aureus sensitive to methicillin or S. pyogenes; it is insect bites, occurs in people whose skin surface was recommended for topical application twice