Skin, Soft Tissue, and Bone Infections IMPETIGO, ABSCESSES, CELLULITIS, AND ERYSIPELA

Objectives Differentiate the various types of skin and soft tissue infections and there clinical presentation Name pathogens commonly involved in skin and soft tissue infections Recognize specimens that are acceptable and unacceptable for different types of skin and soft tissue infections

Describe the microscopic and colony morphology and the results of differentiating bacteria isolates in addition to other non-microbiological investigation Discuss antimicrobial susceptibility testing of anaerobes including methods and antimicrobial agents to be tested Describe the major approaches to treat of skin and soft tissue infections either medical or surgical

Considerations in Skin and Soft Tissue Infection Localization – layer(s) of tissue involved Localized vs. multifocal Disseminated vs. symmetrical Acute, chronic or sub-acute Deep involvement Hematogenous vs. exogenous Host factors, exposures

General Rules in Skin Infection Pustules, tender painful papule or nodule with fluctuance Pyogenic esp. Staph Spreading erythema, painful , recent onset Strep, Pasteurella Bites Cat (Pasteurella), dog (Capnocytophaga), human (Eikenella) Linear nodules Tularemia, Mycobacterium, Sporothrix, Nocardia Vesicles Herpes, Rickettsialpox

Systemic toxicity, pain out of proportion to appearance Necrotizing fasciitis Bullae Vibrio, Capnocytophaga, Campylobacter Gangrene Polymicrobial including Clostridia, enteric GNR Eschar Molds, anthrax, tick borne, septicemia Purpura Meningococcus, Strep, Staph Petechiae Rickettsia, CMV,EBV, HIV (acute)

Classic associations in Skin Infection Finding Organism(s) Mastectomy Group A strep Fish Tank M. marinum Fresh water Aeromonas Thorn, moss Sporothrix Neutropenic, moist area Pseudomonas Neutropenic, tender nodules Candida Splenectomy Capnocytophaga Cirrhosis Vibrio Palms, soles Syphilis, Rickettsia Eschar Molds, anthrax, Rickettsia Lymphadenopathy Bartonella, Tularemia

Skin Infection: Geographic Factors Lyme disease Blastomycosis Yersinia pestis Coccidioides Ehrlichia Vibrio, mycobacteria Leishmania

Fever and Rash: Life threatening Associations Petechial lesions - meningococcal, rickettsial sepsis Mucosal involvement – Stevens-Johnson syndrome Bullae – Toxic epidermal necrolysis, Vibrio Purpura – meningococcus, staph, strep, or pneumococus (purpura fulminans) Ecthyma gangrenosum – Gram negative sepsis

Miscellaneous clues to Etiology of Skin infection Urticaria – hepatitis B (autoimmune reaction) Slapped cheek, sock and glove purpura – Parvovirus Hemorrhagic pustules – Neisseria Nail puncture foot – Pseudomonas Amoxicillin – EBV Chronic severe atopy, severe burns – HSV Intrathoracic or intraabdominal involvement – Actinomycosis, TB Underlying osteomyelitis – S. aureus, Bartonella Lung and /or CNS involvement – Nocardia, endemic mycoses, mycobacteria

Fever and Rash: Important Considerations History must include risk factor assessment – concurrent diseases, medication, travel, occupational/recreational exposure, animals Thorough exam including entire skin area, mucosa, lymph nodes Infectious and non infectious diseases can coexist Skin biopsy for culture and histology rarely contraindicated Acute retroviral syndrome self-inflicted lesions often not considered

Adequate differential diagnosis requires History Patient’s immune status The geographical locale Travel history Recent trauma or surgery Previous antimicrobial therapy Lifestyle Animal exposure or bites Physical Examination Severity of infection

Surgical exploration or debridement Investigation CBCs, Chemistry Swab, biopsy Radiographic procedures Level of infection and the presence of gas or abscess Surgical exploration or debridement Diagnostic and therapeutic

RAJAN S Cleveland Clinic Journal of Medicine 2012;79:57-66

Impetigo Impetigo is a common skin infection Facial impetigo

Causes, incidence, and risk factors Caused by streptococcus or staphylococcus bacteria MRSA is becoming a common cause The skin normally has many types of bacteria on it Intact skin is an effective barrier keeps bacteria from entering and growing in the body When there is a break in the skin bacteria can enter the body and grow there causing inflammation and infection

Breaks in the skin may occur with: Animal bites Human bites Injury or trauma to the skin Insect bites Impetigo may also occur on skin where there is no visible break It is most common in children particularly those in unhealthy living conditions

It is similar to cellulitis In adults it may follow other skin disorders or a recent upper respiratory infection such as a cold or other virus It is similar to cellulitis but it only involves the top layers of the skin Impetigo is contagious, meaning it can spread to others You can catch this infection if the fluid that oozes from the blisters touches an open area on your skin

Symptoms A single or possibly many blisters filled with pus easy to pop and when broken leave a reddish raw-looking base (in infants) Itching blister Filled with yellow or honey-colored fluid Oozing and crusting over

Swollen lymph nodes near the infection (lymphadenopathy) Rash may begin as a single spot but if person scratches, it may spread to other areas Skin lesions on the face, lips, arms, or legs, that spread to other areas Swollen lymph nodes near the infection (lymphadenopathy)

Signs and tests Diagnosis is based mainly on the appearance of the skin lesion A culture of the skin or lesion usually grows the bacteria Streptococcus sp. or Staphylococcus sp. The culture can help determine if MRSA is the cause specific antibiotics are used to treat this infection

Treatment The goal is to cure the infection and relieve the symptoms A mild infection may be treated with a prescription antibacterial cream More severe cases may require antibiotics, taken by mouth Wash (do not scrub) the skin several times a day, preferably with an antibacterial soap, to remove crusts and drainage

Expectations (prognosis) The sores of impetigo heal slowly and seldom scar The cure rate is extremely high the condition often comes back in young children

Complications Kidney failure Many patches of impetigo post-streptococcal glomerulonephritis rare Many patches of impetigo in children Permanent skin damage and scarring very rare Spread of the infection to other parts of the body common

Prevention Prevent the spread of infection use a clean washcloth and towel each time do not share towels, clothing, razors, and other personal care products with other family members wash hands thoroughly after touching the skin lesions Good general health and hygiene help to prevent infection

Thoroughly clean minor cuts and scrapes with soap and clean water You can also use a mild antibacterial soap Impetigo is contagious, so avoid touching the draining (oozing) lesions

Infected impetigo

Bullous impetigo Mainly seen in children younger than 2 years Involves painless, fluid-filled blisters mostly on the arms, legs, and trunk surrounded by red and itchy (but not sore) skin The blisters may be large or small After they break, they form yellow scabs

Bullae Bullous impetigo

Ecthyma Ecthyma is a skin infection similar to impetigo It is often called "deep impetigo“ because it occurs deep inside the skin

Causes, incidence, and risk factors Ecthyma is most often caused by the bacteria Streptococcus sp. Sometimes, Staphylococcus sp. bacteria causes this skin infection The infection may start in skin that has been injured due to a scratch or insect bite It often develops on the legs

Symptoms The main symptom of ecthyma a small blister with a red border may be filled with pus The blister is similar to that seen in persons with impetigo the infection spreads much deeper into the skin After the blister goes away, a crusty ulcer appears

Signs and tests You can usually diagnose this condition simply by looking at patient skin In rare cases the fluid inside the blister may be sent to a lab or a skin biopsy may be done

Treatment You will usually prescribe oral antibiotics Very early cases may be treated with topical medications More advanced forms may need intravenous antibiotics Placing a warm wet cloth over the area can help remove ulcer crusts You may recommend antiseptic soap or peroxide washes to speed recovery

Expectations (prognosis) Unlike impetigo ecthyma can sometimes result in scarring

Complications Spread of infection to other parts of the body Permanent skin damage with scarring

Prevention Carefully clean the skin after an injury such as a bite or scratch Avoid scratching or digging at scabs and sores

The stages of ecthyma The lesion begins as a pustule that later erodes and ultimately forms an ulcer Typical ecthyma lesions of the lower extremities

Skin abscess A skin abscess is a build up of pus in or on the skin An abscess is a collection of pus (neutrophils) that has accumulated within a tissue an inflammatory process in response to an infectious process or other foreign materials It is a defensive reaction of the tissue to prevent the spread of infectious materials to other parts

Causes Skin abscesses are common They occur when an infection causes pus to collect in the skin Skin abscesses may occur after: A bacterial infection (often staphylococcus) A minor wound or injury Boils Folliculitis A skin abscess may occur anywhere on the body The problem affects people of all ages

Symptoms Symptoms may include: Fever or chills, in some cases Local swelling around the infected spot Hard of tissue (induration) Skin lesion that may be an open or closed sore, or domed nodule Redness, tenderness, and warmth in the area Fluid drainage

Exams and Tests You could diagnose the problem by looking at the affected area The drainage from the sore may be sent to the lab for a culture This can help identify the cause of the infection

Treatment You can apply moist heat to help the abscess drain and heal faster DO NOT push and squeeze on the abscess The health care provider may cut open the abscess and drain it You may need to describe antibiotics by mouth to control the infection

Outlook (Prognosis) Most skin abscesses can be cured with proper treatment Infections caused by MRSA are do not respond to regular antibiotics and need special medicines

Possible Complications Spread of infection in the same area Spread of the infect in the blood and throughout the body Tissue death (gangrene)

Prevention Keep the skin around minor wounds clean and dry to prevent infection Call your health care provider if you notice signs of infection Take care of minor infections promptly

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