Bacterial infections of SkinBacterial infections of Skin

Learning objectives of bacterial infectionsLearning objectives of bacterial infectionsof skinof skin

Define Pyoderma and classify it.

 List the normal flora of skin.

  Define impetigo. List the differentiating features of

bullous and non-bullous impetigo.

Describe the C/F, investigations of impetigo.

Outline the management of impetigo.

Learning objectives of bacterial infections of skin

·                        Define folliculitis , classify it and describe the

management of it.

Describe the C/F, investigations and management of

ecthyma/ cellulites/ erysipelas/ furuncle/ carbuncle/ SSSS.

·                   List the skin infection produced by B- hemolytic

streptococci.

·              List the skin infection produced by staphylococci.

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

3. Transient or temporary residents

Normal Skin Flora

• Major bacterial groups

– Coryneforms (Gram +ve, pleomorphic rods)

Corynebacterium (Aerobic & lipophilic)

Brevibacterium (Aerobic & non-

lipophilic)

Propinobacterium (Anaerobic)Contd…

- 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 pyodermas1. Primary

Impetigo Ecthyma Folliculitis

– Superficial

– Deep* Folliculitis of leg

* Furuncle

* Carbuncle

* Sycosis Barbae

• Cellulitis/ Erysipelas• Pyonychia• SSSS• TSS

2. SecondarySecondary infection of preexisting dermatoses

eg. Atopic dermatitis, Scabies

Impetigo (contagious superficial infection)

Non-bullous Bullous1. Cause

- Streptococcal (Group A) Staph. aureus

- Staph. aureus (Phage Groups II)

2. Pre-school and young school age All ages

3. Very thin walled vesicle on an erythematus base Bullae of 1-2cm

4. Transient Persist for 2-3 day

5. Yellowish-brain crusts (thick) Thin, flat,

brownish crust

Contd…

6. Irregular peripheral extension without Central healing with healing peripheral extension

7. Regional adenitis Rare

8. Constitutional symptoms present Absent

9. Face (around the nose, mouth & limbs) occur anywhere

10. Palms & sole spared May involved

11.MM, very rare May 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

Folliculitis

• Deep folliculitis of leg

• Chronic

• Staph. aureus

• Hair follicles of leg

• Multiple

• Atrophic scar

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 synotrane (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 7 - 14 day

• Don’t grow staph. from blister fluid

• Complication 2%

– Cellulitis

– Pneumonia

• Prognosis : Rule

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

• Replacement of microflora with a less pathogenic

stains of S.aurus (strain 502)

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 toxina. Staphylococcal scalded skin syndrome

b. Toxic shock syndrome

ß-hemolytic streptococcus produces skin infection

I. Direct infection of skin or subcutaneousa. Impetigo (non bullous)

b. Ecthyma

c. Erysipelas

d. Cellulitis

e. Vulvovaginitis

f. Blistering distal dactylitis

g. Necrotizing fascitis

II. Secondary infectionEczema 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

Consider the following in relation to bacterial infection of skin

•a.     Cellulitis is the inflammation of subcutaneous tissue as well as dermis caused by Streptococcus.

•b.   Bullous impetigo is caused by streptococci

•c.      In erysipelas, inflammation is limited to dermis and upper

• part of subcutaneous tissue.

•d.     Furunculosis is caused by Streptococcus

Thank you