BACTERIAL SKIN DISEASES

carbuncle Etiology:

- A carbuncle is a deep infection of a group of contiguous follicles with staph. aureus accompanied by intense inflammatory changes in the surrounding and underlying connective tissues. - They may be seen in the apparently healthy but are more common in the presence of diabetes ,malnutrition, cardiac failure and during prolonged steroid therapy.

Clinical features:

- A furuncle first presents as a small follicular inflammatory nodule soon becoming pustular and then necrotic and healing after discharge of a necrotic core to leave a violaceous macule and a scar. - On the upper lip and cheek cavernous sinus thrombosis is a rare and dangerous complication - The sites commonly involved are the face and neck,the arms,the fingers,the buttocks and anogenital region. - Attacks may consist of a single crop or multiple crops at irregular intervals which continue for many months or even years.

Etiology:

- Common in adolescence and early adult life the infection strain of staphylococcus is usually also present in the nares or the perineum. - From the sites of carriage the infection is disseminated by the fingers and by clothing. mechanical damage to the skin even the friction of collars and belts may determine the distribution of the lesions. - Malnutrition is an important predisposing factor in some countries. however in a high proportion of cases no convincing predisposing factor can be responsible.

furuncle (boil) def

A furuncle is an acute, usually necrotic infection of a hair follicle with staph aureus.

cellulitis & erysipelas Clinical features:

- Erythema,heat ,swelling and pain or tenderness are constant features. In erysipelas the edge of the lesion is well demarcated and raised but in cellulitis it is diffuse. - In erysipelas blistering is common and there may be superficial hemorrhage into he blisters or in intact skin especially in elderly people. - In cellulitis the skin shows erythema, oedema, hotness, pain and tenderness with illdefined border. - Severe cellulitis may show bullae and can progress to dermal necrosis.lymphangitis and Lymphadenopathy are frequent. except in mild cases there is constitutional upset with fever and malaise. - Classical erysipelas starts suddenly and systemic symptoms may be acute and severe . - The leg is the commonest site and here there is usually a wound even if superficial ,an ulcer or an inflammatory lesion including interdigital fungal are possible portal of entry. - The next most frequent site for classical streptococcal erysipelas is the face where a traumatic entry site is less commonly seen. Without effective treatment,complications are common: fasciitis, myositis,subcutaneous abscesses,septiceamias and in some streptococcal cases nephritis and the more severe infection may be fatal in infants and in the debilitated or immunosuppressed. Periorbital and orbital cellulitis may be complicated by cavernous sinus thrombosis.

Treatment:

- Flucloxacillin systemically or another penicillinase resistant antibiotic. - A topical antibacterial agent reduces contamination of the surrounding skin. - occlusive dressings should be avoided. - In recurrent cases exclude diabetes. nasal and perineal carriage should be sought in the patient and other household members.

Treatment of ecthyma

- Improved hygiene and nutrition and treatment of scabies and any other underlying disease are important. - The antibiotic chosen should be active against both strept and staph.

Treatment of impetigo

- In mild and localized infection a local antibiotic as mupirocin oint may be enough. - In both Staph and Strept infection. fusidic acid is also effective against both organisms but in order to reduce the likelihood of the development of resistance because of its value in systemic infection it may be better to restrict its use. - Topical neomycin and bacitracin are often used in combination. - If the infection is widespread or severe or is accompanied by lymphadenopathy or suspect a nephritogenic streptococcus an oral antibiotic such as flucloxacillin or erythromycin is indicated. - Removal of infected crusts with washing with soap and water or potassium permanganate compresses 1/8000 concentration help also in the treatment. - proper hygienic measure and eradication of predisposing factors such as insect bites, pediculosis, scabies and minor tauma reduce the transmission of infection.

Clinical features:

- Painful, hard red swelling. it increases in size for a few days to reach a diameter of 3-10 cm or more. suppuration beginning after 5-7 days and pus is discharged from the multiple follicular orifices. necrosis of the intervening skin usually occurs. - Most lesions are on the back of the neck,the shoulders or the hips and thighs. - Constitutional symptoms may accompany or precede the development of the carbuncle in the form of: Fever , malaise and prostration which may be severe if the carbuncle is large or the patient's general condition is poor. - In favourable cases healing slowly takes place to leave a scar. - In bad general condition, death may occur from toxaemia. Treatment: - Flucloxacillin or another penicillinase resistant antibiotic should be given. - Diabetes or other possible underlying conditions should be thought of. - Surgical intervention may be needed.

Clinical features of ecthyma

- Small bullae or pustules on an erythematous base are soon covered by hard crusts of dried exudates. - the base may become indurated and a red oedematous areola is often present. - - The crust is removed with difficulty to reveal a purulent irregular ulcer. - Healing occurs after a few weeks with scarring. - Autoinoculation may lead to multiple lesions. - The buttock ,thighs and legs are most commonly affected.

bacterial folliculitis

- Staphylococcal infection is a common cause of superficial folliculitis. - Follicular impetigo of Bockhart is an infection of the follicular osteum with staph aureus. it is commonest in childhood and occur mainly in the scalp or scalp margins or on the limbs. - The individual lesion is a yellow pustule sometimes with a narrow red areola. the pustules develop in groups and may heal within 7-10 days, but sometimes become chronic. Treatment: - Mild staphylococcal folliculitis is often self limiting. - In more severe cases antibiotics topical or systemic may be required. - If the infection is persistent or recuurent, the usual sites of staphylococcal carriage (nose and perineum) should be thought of in the patient and his or her contacts.

Erysipelas VS Cellulitis

- organism: strept - general manif: always present - local manif: . well defined raised border erythema . edema w hotness, redness . surface may show bullae - site: common on the face - strept. staph, or haemophelous influenza - mb present or not - ill defined border erythema . edema. hotness, pain, tenderness . surface may show necrosis - common in extremities BOTH type may end w lymphoedema & vicous circle i.e. edoema ppt. for cellulites

non-bullous impetigo

- staphylococcus aureus - streptococci - both

Clinical features of impetigo

-In bullous impetigo, the bullae are less rapidly ruptured and become much larger. -the contents are at first clear later cloudy. -after rupture thin flat brownish crusts are formed, central healing and peripheral extension may give rise to circinate lesions. -the lesions may occur anywhere. -regional adenitis is rare. - In non-bullous impetigo, the initial lesion is very thin-walled vesicle on an erythematous base, the vesicle ruptures so rapidly that it is seldom seen as such. - The exuding serum dries to form yellowish brown crusts. The crusts eventually dry and separate to leave erythema which fades without scarring. - In severe cases there may be regional adenitis with fever and other constitutional symptoms.

cellulitis & erysipelas Bacterially:

Bacterially: Cellulitis and erysipelas are predominantly streptococcal diseases. In cellulitis, staph is occasionally implicated alone or together with strept. Hamophilus influenza is an important cause of facial cellulitis in young children.

Clinical Types of Impetigo

Bullous. Circinate. Nonbullous, crusted, Telbery Fox. Secondary. Ecthyma. Follicular, ostial, Bock hart.

cellulitis & erysipelas Definition:

Cellulitis is strictly an acute, subacute or chronic inflammation of loose connective tissue of the subcutaneous tissue in which an infective generally bacterial cause is responsible. Erysipelas is a bacterial infection of the dermis and upper subcutaneous tissue, - its main feature is a well-defined raised edge reflecting the more superficial (dermal) involvement. - however cellulitis may extend superficially and deeply so that in many cases the two processes coexist and it is impossible to make a distinction.

impetigo contagiosum def

Definition: Impetigo is a contagious superficial pyogenic infection of the skin. Two main clinical forms are recognized: -bullous impetigo -Non bullous impetigo or (impetigo contagiosa of Tilbury fox or crusted imetigo).

erythrasma

Definition: Is a mild,localized superficial infection of the skin caused by corynebacterium Minutissimum. Etiology: Clinical infection may occur at any age but is more common among adults than children,diabetes may be a predisposing factor.,obesity and warm humid climate are predisposing factors also. Clinical features: - It occurs most commonly in the groins,axillae and the intergluteal and submammary flexures,in the groins,it affects the area in contact with the scrotum. - The patches are of irregular shape and sharply marginated,at first red but later becoming brown, new lesions are smooth but older lesions tend to be finely wrinkled or scaly. D.D. of erythrasma: Intertrigo: Frictional dematitis. Tinea cruris. Flexural psoriasis. Seborrhoeic dermatitis Fluorescence under wood's light: Coral red fluorescence with wood's light strongly suggest erythrasma. Treatment: Erythrasma responds well to most topically applied azole antifungal agents such as clotrimazole and miconazole(although it is a bacterial infection) for two weeks. For more extensive lesions erythromycin is probably the most effective approach, alternatives include topical fucidin and oral tetracycline.

Pathology of impetigo

In bullous impetigo - The epidermis splits just below the stratum corneum or granulosum forming large blisters. - Neutrophils migrate through the spongiotic epidermis into the blister cavity which may also contain cocci. - The upper dermis contains an inflammatory infiltrate of neutrophils and lymphocytes. Non bullous impetigo - Similar to bullous - Except that blister formation is slight and transient.

ecthyma def

Is a pyogenic infection of the skin characterized by the formation of adherent crusts ,beneath which ulceration occurs.

Treatment:

Penicillin is the treatment of choice and should be continued for 10 days. In recurrent cases long acting penicillin can prevent attacks. In patients allergic to penicillin another drug commonly erythromycin should be taken. Some patients may require life long prophylaxis.

sites of Impetigo

The face especially around the nose and mouth and the limbs are the sites most commonly affected, but involvement of the scalp and the body especially in children with atopic dermatitis or scabies.

bullous impetigo

staphylococcal dis