Dr.Ahmed Abdul-Aziz Ahmed Assistant Clinical Professor Dermatology&Venerology. F.I.B.M.S.

1.Bacterial Skin infction 2.Acne Rosacea 3.Urticaria 1.Bacterial Skin infction 2.Acne &Rosacea 3.Urticaria &Angioedema&Erythemas 4.Genodermatosis

Bacterial Skin Infection

Basic structure of infectious agents VIRUSES BACTERIA FUNGI PROTOZOA HELMINTHS Cell structure Not applicable Prokaryotic Eukaryotic Eukaryotic Eukaryotic Size DNA and RNA No Yes Yes Yes Yes Living? No Yes Yes Yes Yes Nucleus? Not applicable No Yes Yes Yes Ribosomes Not applicable 70S 80S 80S 80S Internal organelles Not applicable No Yes Yes Yes Multicellular? Not applicable No Both No Yes Cell wal l Not applicable Yes,peptidoglycan Yes, chitin No No

Major families of bacteria Gram Positive bacteria: Staphylococcus, Streptococcus, Clostridium, Corynebacterium. Stain blue Gram Negative bacteria: Haemophillus, Enterobacter, Neisseria, Proteus, E. Coli, Klebsiella, Citerobacter, Pseudomonas, Morganella, Shigella, and Serratia. Stain red

Major families of bacteria Aerobic bacteria: Most of the above are aerobic organisms, meaning they exist in environments with oxygen. Anaerobic bacteria: Exist in environments without oxygen. Peptostreptococcus (most common), Peptococcus, Clostridium, and Bacteroides. Infections usually smell putrid.

Pathogenesis Primary Infections Usually affect normal skin, entering through a break in the skin such as an insect bite. Characteristic clinical picture and disease course Caused by a single pathogen Many systemic infections involve the skin Secondary Infections: Infection of skin that is already diseased. Variable clinical picture because of the underlying disease

Medstat.med

9 Impetigo Contagiosa

10 Impetigo Contagiosa

Impetigo on an uncommon site showing erosions, crusting and rupture blisters.

12 Impetigo Contagiosa

13 Bullous Impetigo

14 Bullous Impetigo

Bullous Impetigo

Impetigo contagiosa Impetigo

Circinate impetigo: with peripheral extension of lesion & healing in the center. Varities:

Crusted impetigo: on the scalp complicating pediculosis. Occipital & cervical LNs are usually enlarged & tender.

Age: all ages, but commoner in childhood & newborn (impetigo neonatorum). Site: face is often affected, but the lesions may occur anywhere, including palms & soles. Bullous Impetigo

The bullae are less rapidly ruptured (persist for 2-3 days) & become much larger. The contents are at first clear, later cloudy. After rupture, thin, brownish crusts are formed.

Ecthyma (ulcerative impetigo): adherent crusts, beneath which purulent irregular ulcers occur. Healing occurs after few wks, with scarring.

25 Ecthyma

Ecthyma

Staphylococcal scalded skin syndrome in a child. The overlying epidermis is loosening in the red areas

Staphylococcal scalded skin syndrome Exfoliatin (epidermolysin) split off the upper part of the epidermis just beneath the granular cell layer. The inciting infection may be on the skin but usually is in the eye or nasopharynx. The toxin enters the circulation and affects the skin systemically, as in scarlet fever. Nikolosky’s sign

31 Staphylococcal Scalded Skin Syndrome

32 Staphylococcal Scalded Skin Syndrome

SSSS and TEN

FOLLICULITIS

Folliculitis Fc

a dome-shaped pustule at the orifice of a hair follicle that heals within 7-10 days. Superficial Folliculitis (Bockhart’s Impetigo)

from penetration into the skin of sharp tips of shaved hairs. pseudofolliculitis

It is a staphylococcal infection similar to, but deeper than folliculitis & invades the deep parts of the hair folliculitis. Occasionally several closely grouped boils will combine to form a carbuncle. The carbuncle usually occurs in diabetic cases. The site of election is the back of the neck. Frunculosis (boils)

41 Furuncle

42 Furuncle / Carbuncle

Boils. Furuncles Bs

) Carbuncle

CELLULITIS & ERYSIPELAS

Cellulitis

Cellulitis Limbs Redness. Swelling Increased warmth Tenderness Blistering Regional lymphadenopathy Abscess

Cellulitis

Erysipelas Well-defined, raised border and marked swellingf affected skin.

Erysipelas note sharp spreading edge, here demarcated with a ballpoint pen.

51 Erysipelas

52 Cellulitis

53 Cellulitis

 Erythema, heat, swelling and pain or tenderness.  Fever and malaise which is more severe in erysipelas.  In erysipelas: blistering and hemorrhage.  Lymphangitis and lymphadenopathy are frequent.

Edge of the lesion: well demarcated and raised in erysipelas and diffuse in cellulitis.

SKIN DISEASES RELATED TO CORYNEFORM BACTERIA Erythrasma

It is mild, chronic, localized superficial infection of skin by Coryn. Minutissimum. Clinically: sharply- defined but irregular brown, scaly patches

Pitted keratolysis of the heel

usually localized to groins, axillae, toe clefts or may cover extensive areas of trunk & limbs. Obesity & DM may coexist. Coral red fluorescence under wood’s light.

60 Intertrigo Presentation: Superficial inflammatory dermatitis where two skin surfaces are in apposition. Etiology: Friction and moisture allows infection by bacteria (Staph, Strep, Pseudo.) or fungi or both.

61 Intertrigo

62 Intertrigo

63 Intertrigo

64 Pyogenic Paronychia Presentation: Tender painful swelling involving the skin surrounding the fingernail. Etiology: Moisture induced separation of eponychium from nail plate by trauma or moisture leading to secondary infection. Often work related Bacteria cause acute abscess formation, Candida causes chronic swelling. Treatment: Avoid maceration / trauma I&D of abscess PCN, 1 st Gen Cephalosporin, augmentin. Chronic infection requires fungicide and a bactericide.

65 Pyogenic Paronychia

66 Pyogenic Paronychia

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