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
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