Infections Of The Skin, Muscle, & Soft Tissue

Infections of the Skin, Muscle and Soft Tissue •

Terminology o Macule – circumscribe lesion different in color from surrounding skin o Patch – a macule > 1cm in diameter o Papule – an elevated circumscribed lesion of any color of < 1cm in diameter o Nodule – a papule > 1cm o Plaque – nodule > 2cm o Vesicle – an elevated marginated lesion filled with clear fluid < 1cm o Pustule – a well marginated focal accumulation of pus within the skin o Wheal – a transient elevate lesion in the upper dermis containing fluid

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Infections Associated with Vesicles o Varicella  Vesicles have dewdrop appearance and develops centrifugally  Children are more affected o Herpes-zoster -“Shingles”

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Vesicles occur in a single dermatome and preceded by pain (hyperesthesia or radicular pain)for several days

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Unilateral eruption and doesn’t cross the midline Reactivation of a latent Varicella-Zoster viral infection in the dorsal root ganglia – migrates along the sensory nerves to the skin May occur at any age but common in immuno- suppressed individuals ang elderly Diagnosis • Visual identification confirmed with Tzanck smear • Culture 50% right

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HSV  Herpes gladiatorum – in wrestlers  Herpetic whitlow – health care workers Cocksackievirus A16  Vesicles on hands, feet and mouth of children Orf  Poxvirus  Infects finger of goat and sheepherders Molluscum contagiosum  Flaccid vesicles Rickettsialpox  From mite-bite  Central vesicle with black eschar with white halo and proximal adenopathy Blistering dactylitis  S. areus and Grp A Strep  Pulp of distal digit of the hands

Infections Associated with Bullae o Staphylococcal scalded syndrome (SSS) o Toxic epidermal necrosis  Similar to SSS but is drug-induce and has a higher mortality o Necrotizing fascitis and gas gangrene also causes bulla o Halophilic vibrio infectio  Aggressive and fulminant  Hx of exposure to waters of Gulf of Mexico and Atlantic Seaboard  Hx of ingestion of raw food Infections Associated with Crusted Lesions o Impetigo contagiosa  S. pyogenes  Golden-brown thick crust o Bullous Impetigo  S. aureus

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 Golden-brown thick crust Streptococcal lesions  Common to 2-5yrs old  Poor hygiene; low economic status  Impetigo contagiosa • rapidly spreading erythema with vesicular or denuded areas with salmon colored crust • Asso with poststreptococcal glomerulonephritis Superficial dermatophyte infection (ringworm)  KOH staining for diagnosing Dimorphic fungi  Initially presents as crusted skin lesion resembling ringworm Coccidioides immitis Mycobacterium Chelonei  Crusted nodular lesion  In HIV-seropositive patient

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Folliculitis o Pruritic burning pain in areas with hair follicles o Pustules in hair follicles caused by Staph o Staphyloccocal cyst may resemble sebaceous cyst o “hot tub folliculitis”  P. aeroginosa  Diffuse folliculitis  Water insufficiently chlorinated  Self limiting o Pseudo folliculitis caused by ingrowing hairs in bearded area o “fresh water itch”  diffuse folliculitis  Water infested with avian schistosomes

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Papular and Nodular Lesion o M. marinum  May present as cellulites or raised erythematous nodules o Erythematous papules  Cat-scratch dse • Primary lesion (papule, pustule, conjunctivitis) • 1-3 wks after scratch – fever, malaise and headache with regional lymphadenopathy  Bacillary amgiomatosis ( Bartonella henselae)  Contact with dog or cat feces in soil o Dracunculiasis  Burrowing lesion o Ochocerca volvulus  Bite from Simulium flies  Migration into eyes may cause blindness o Verruca peruana  Bartonella bacilliformis  Transmitted by sandfly, Phlebotomus  A single gigantic lesion or may be multiple small lesions o Cysticercosis  May present numerous subcutaneous nodules o Schistosomiasis  Numerous erythematous papules o Lepromatous leprosy  Skin nodules as well as thickened subcutaneous tissue o Syphilis  Tertiary • Large nodules or gummas  Secondary

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HPV 

Flat papulosquamous lesion

May cause single warts (verruca vulgaris) or multiple warts in the anogenital area (condylomata acuminata)

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Ulcers with or without Eschars o Cutaneous anthrax  Begins as pruritic papule; develops an ulcer w/ surrounding edema and then into a large ulcer with a black eschar  May cause nonhealing ulcer with overlying dirty-gray membrane • May mimic psoriasis, eczema or impetigo o Ulceroglandular tularemia  Ulcerated skin lesion with painful regional adenopathy o M. ulcerans  On extremities in the tropics o M. tuberculosis  Ulcerations, papules, ertyhematous macular lesions of the skin in both normal and immunocompromised o M. leprae  Cutaneous ulcerations  Related to Lucio’s phenomenon or during reversal reaction o Decubitus ulcers  Due to tissue hypoxia secondary to pressure induced vascular insufficiency o Ulcerative lesions on the anterior shins  May be due to pyoderma gangrenosum o Ulcers on genitals  Painful – chancroid  Painless – primary syphilis

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Erysipelas o Due to S. pyogenes o A.K.A. St. Anthony’s Fire  Abrupt onset of fiery-red swelling of face and extremities o

 A superficial cellulitis with marked involvement of the lymphatics Distinct features: 

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Well-indurated margin, particularly in the nasolabial fold  Rapid progression  Intense pain Diagnosis  An erythematous, warm, indurated, plaue with shapr borders  Commonly involves the face  Superficial location of lesion

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+ lymphatic involvement yields edema and “Peau d’ Orange” appearance

Lesions don’t itch; they hurt  Flaccid bullae may develop  Extension to deeper tissues is rare Treatment:  Penicillin  Erythromycin  Cephalosporin

Cellulitis o Definition  A rapidly spreading infection of the dermis and subcutaneous tissues  Characterized by localized pain, erythema, swelling and heat  Clinical locations • Cellulitis of the extremities • Facial cellulitis

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• Periorbital cellulitis (H. Influenza) • Perianal cellulitis Etiologies • Predominantly o Staphylococcus sp (centrally localized infections)  Common in px with eosinophilia and elevated IgE (Job’s syndrome) o Strep sp (more rapidly, diffuse process; assoc with lymphangitis and fever)  Common in patients with chronic lymphedema, lymph node dissection and Milroy’s • In wounds secondary to animal bite - consider Pasteurella multocida • Facial cellulitis usually cultures H. influenza B o Assoc with sinusitis, otitis media, or epiglottitis • P. aeroginosa (3 types) – following penetrating injury o Ecthyma gangrenosum o Hot-tub folliculitis o cellulitis Portal of entry • Cracks in skin, abrasions, cuts • Burns • Insect bites • Surgicaol insicion, intravenous catheters Diagnosis • Erythematous lesion that is swollen and tender with an indefinite border that may involve a large area of the skin • A rapidly spreading infection • Elevated WBC. + cultures in 50% cases Screening and Tests • Gram’s staining and culture o When there is drainage o Open wound o Obvious portal of entry • Needle aspiration of the leading edge • Punch biopsy of the cellulitis tissue itself Treatment • Dependent on the organism and severity of the disease o Mild infections  Penicillin for Strep  Erythromycin or Cephalosporin for Staph  Amoxicillin-Clavulanic acid for bites  Severe infections require IV medication dependent upon organism isolated and hospitalization

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Necrotizing Fasciitis o A.K.A. streptococcal gangrene o Associated with Grp A Strep o May be Clostridium perfringens o Chronology of sighns and symptoms  Pain and unexplained fever are the only symptoms early in the dse  Swelling develops followed by brawny edema and tenderness  Dark red induration of the epidermis along with bullae filled with blue or ourple fluid  The skin becomes friable and takes bluish, maroon, or black color  Thrombosis of blood vessel becomes extensive  Patient later becomes toxic (parang med student) and frequently manifest shock and multiorgan failure

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Myositis / Myonecrosis o Muscle involvement with virus or parasitic infection o Myalgia in most infections

Severe muscle pain as hallmark in:  Pleurydonia (cocksackie)  Trichinosis  Bacterial infection o Acute rhabdomyolysis in  Clostridial and Streptococcal myositis o Pyomyositis  Due to S. aureus in the tropics  Generally has no portal of entry  Infections usually remains localized  In S. pyogenes – primary myositis (streptococcal necrotizing myositis) o Myonecrosis occurs concomitantly with necrotizing fasciitis  Both part of streptococcal shock syndrome Gas gangrene usually follows o

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