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Bacterial infections of Skin

Normal flora of skin Classification: 1.Resident flora: grow on skin & relatively stable in no. and composition at particular sites 2.Transient flora: lie on skin surface without attachment, unable to multiply & disappear within short time

Normal Skin Flora Major bacterial groups –Coryneforms - Staphylococci (Gram +ve cocci, aerobs) S. epidermidis, S. hominis, S.hemolyticus, S. saprophyticus Minor bacterial groups –Acinetobacter (25%) –Micrococci Fungal group –Pityriasporum

Bacterial infection of the skin (Pyoderma) Classification of pyodermas 1.Primary  Impetigo  Ecthyma  Folliculitis –Superficial –Deep *Furuncle *Carbuncle *Sycosis Barbae

Cellulitis/ Erysipelas Pyonychia SSSS TSS 2.Secondary Secondary infection of preexisting dermatoses eg. Atopic dermatitis, Scabies

Impetigo (contagious superficial infection) Non-bullousBullous 1. Cause - Streptococcal (Group A)Staph. aureus - Staph. aureus (Phage Groups II) 2.Pre-school and young school ageAll ages 3.Very thin walled vesicle on an erythematus base Bullae of 1-2cm 4.TransientPersist for 2-3 day 5.Yellowish-brain crusts (thick)Thin, flat, brownish crust Contd…

6. Irregular peripheral extension withoutCentral healing with healing peripheral extension 7.Regional adenitisRare 8. Constitutional symptoms presentAbsent 9.Face (around the nose, mouth & limbs)occur anywhere 10. Palms & sole sparedMay involved

–Malnutrition –Diabetes –Immuno-compromise status Complications –Streptococcal infection –PSGN (strep M-type 49) –Scarlet fever –Urticaria –Erythema mutiforme Predisposing factors

Ecthyma Streptococcal & staph Common in children Small bullae or pustules on erythematous base Formation of adherent dry crusts Beneath which ulcer present Indurated base Heals with scar and pigmentation Buttocks, thighs and legs, commonly affected

Folliculitis Superficial folliculitis Infection of hair follicles Commonly caused by staph. aureus Children Scalp & limb Rarely painful Heals in a week

Furuncle (Boil) Acute Staph. aureus Small, follicular noduler -- Pustule--necrotic- -discharge pus Painful Constitutional symptoms

Heals with scar Age: Adult Site: Neck, Wrist, Waist, Buttocks, Face Complication Cavernous Sinus thrombosis, (upper lip & check) Septicemia (malnutrition)

Carbuncle Extensive infection of a group of contagious follicles Staph. aureus Middle or old age Predisposing factors –Diabetes –Malnutrition –Severe generalized dermatoses –During prolonged steroid therapy

Painful, hard lump Suppuration begins after 5-7 days Pus discharge from multiple follicular orificies Necrosis of intervening skin Large deep ulcer Constitutional symptoms

Sycosis barbae Beard region Pustules surrounded by erythema Males After puberty After trauma Upper lip and chin Staph. aureus

Cellulitis Acute/sub-acute/chronic Inflammation of loose connective tissue Streptococcal (Group A) Erythematous, edematous, swelling Pain/tenderness Constitutional upset

Pyonychia Acute Erythematous swelling of proximal and lateral nail fold Painful

Staphylococcal scalded skin syndrom (Ritter’s Disease) Exotoxin of staph (Phage Group II) Acantholysis Occult staph. upper respiratory tract infection or purulent conjunctivitis Infants and children Tender red skin

Staphylococcal scalded skin synotrane (Ritter’s Disease) Denuded skin Heals day Don’t grow staph. from blister fluid Complication 2% –Cellulitis –Pneumonia Prognosis : good / 3% death

Principles of therapy of pyoderma Good personal hygiene Management of predisposing factors –Local Attend to traumas, Pressure, Sweating, Bites Treat pre-existing dermatosis Investigate carrier sites: Nose, Axilla, Perineum Systemic Treatment of disease like DM Nutritional deficiency Immunodeficiency

Principles of therapy of pyoderma Local therapy –Cleaning with soap-water and weak KMN04 solution –Removal of crusts with KMN04 soluation –Application of antibacterial cream Systemic therapy –Antibiotics

Recurrent staphylococcal infection Persistent nasal carriage Abnormal neutrophitic chumotaxis Deficient intracellular killing Immunodeficient status D.M.

T/t of staph. carriage elimination Nasal & perineal care Rifampicin 600 mg/d 7-10 days Clindamycin 150 mg/d 3 months Topical mupirocin

S.aureus produces skin infection I. Direct infection of skin and adjuscent tissues a.Impetigo b.Ecthyma c.Folliculitis d.Furunculosis e.Carbuncle f.Sycosis II.Cutaneous disease due to effect of bacterial toxin a.Staphylococcal scalded skin syndrome b.Toxic shock syndrome

ß-hemolytic streptococcus produces skin infection I. Direct infection of skin or subcutaneous a. Impetigo (non bullous) b. Ecthyma c. Erysipelas d. Cellulitis e. Vulvovaginitis f. Blistering distal dactylitis g. Necrotizing fascitis II. Secondary infection Eczema infection

III. Tissue damage from circulating toxin Scarlet fever IV. Skin lesion attributed to allergic hypersensitivity to streptococcal antigens E.Nodosum Vasculitis V. Skin disease provocated or influenced by streptococcal infection (mechanism uncertain) Guttate psoriasis

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