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Numerous microorganisms can penetrate the skin disease. Resident bacterial flora is often a major offender.

Classification:

• Primary

• Secondary

Common bacterial pathogens:

• Staphylococci aureus

• Streptococcal

Primary lower extremity bacterial infections

• Impetigo (epidermal)

o Caused by Staph. or Strept.

o Children>adults

o Contagious, superficial infection

o Vesicles which rupture to form pustular yellow exudate

o < face

o Impetigo contagiosa

o Bullous impetigo

o Secondary impetigo (Impetiginization)

• Ecthyma (dermal)

o Caused by Staph. or Strept

o <homeless people

o Ulcerated, crusted & infected lesion

• Cellulitis

o Acute, aggressive infection

o Staph or Strept.

o Dermal and tissue subcutaneous

o Sharply demarcated, erythematous, tender plaque

o Fever, malaise & fever

o Lymphatic streaking

• Erysipelas

o Superficial form of cellulitis

o Sharply demarcated, erythematous, oedematous plaque - hot and tender

o Direct innoculation of skin

o Fever, malaise, flu like symptoms

o Group A beta-haemolytic streptococci

Secondary lower extremity bacterial infections

• Intertrigo:

o Non-specific inflammation between two surfaces

o Friction & moisture

o No bacterial or fungal infection present

• Intertriginous infection

o Friction & moisture

o Common interdigitally

o Bacterial form includes:

• Erythrasma

• Chronic bacterial infection

• Corynebacterium minitissimum

• Burning, pruritus, maceration, fissuring

o Fungal form includes

• Intertriginous tinea pedis

• Candida albicans, T. rubrum

• White (sometimes green tinge) macerated skin

• Fissuring and loss of epidermis

• 4th web space

Other fungal infections

• Fungal granuloma:

o Perifollicular infection – T. rubrum

• Onychomycosis:
o Very common nail infection

• Paronychia

o Chronic form is often caused by Candida infection of the periungual tissue