Bacterial skin infections Dr. Asmaa Alajeel Bacterial skin infections • The skin infections could be acute or chronic infections. • Some bacteria are considered as normal flora of the skin , mainly consist of staphylococcus epidermidis , other are corynebacterium , propoinibacterium acne and pityrosporum ovales which is a monocellular yeast and these types called resident flora which are harmless bacteria and does not cause skin infection, only in certain conditions ( immunocompramized person, aids patients) . Other types are the transient flora which includes most of the pathogenic bacteria. • Infections caused by G +v organism • The 2 G+ cocci staphylococcus aureus and group A β hemolytic streptococci account for the majority of skin and soft tissue infection. Impetigo • it is a staphylococcus, streptococcus or combined infections characterized by thin wall blister ruptured easily leaving a honeycomb like yellow crustations. Occur most frequently on the exposed part of skin mainly face, also neck and extremities. It is a very contagious disease particularly in children. Rarely impetigo is complicated by serious staphylococcus. Scalded skin syndrome or in case of streptococcus by glomerulonephritis. • Diagnosis is usually made on clinical ground, swab should be taken and send for culture. • . Impetigo • Treatment: for minor cases removal of crust and topical antibiotics such as neomycin, fucidic acid, mupirocin or bacitracin. In severe cases combined with systemic antibiotics impetigo Bullous impetigo • A variety of impetigo occurs characteristically in new born infant especially after insect bites or in older people in nurseries after skin injuries. This condition is with larger lesion and long course and spread quickly. Staphylococcal scalded skin syndrome • Affects neonates and young children caused by exfoliative toxin of group 2 staph aureus that cause splitting of the epidermis under or in the granular cell layer causing sheeting and exfoliation of the skin allover the body leaving erythematous skin. • It is self limiting disease treated by fluid therapy, general supportive measures and systemic antibiotics. The prognosis is good. Toxic shock syndrome • An acute febrile multisystemic illness caused by staph toxin isolated from cervical mucosa of menstruating women used tampons or due to infection in wound, catheter and nasal packing, manifest as fever, rash, erythema and circulatory collapse followed 1-2 weeks by desquamations of hand and soles. • Treatment: by vigorous fluid therapy, systemic antibiotics and irrigation of infected site. Folliculitis • Infections of the hair follicles caused by staphylococcus, if affectes the super facial part called superficial folliculitis and involve the ostium of the hair follicles. If it is deep then change to carbuncle or boil. • There are different types of folliculitis: folliculitis Folliculitis • Superficial pustular folliculitis ( bockhart impetigo ):- fragile pustules arranged in crops and heal in few days on scalp and extremities . • sycosis vulgaris : perifollicular , chronic pustular infection of beared area . • folliculitis decalvans : rare condition affects scalp area characterized by pustular infection of scalp after healing leave scarring alopecia behind. • The term pseudofolliculitis is not a bacterial infection, usually seen in beard area of male and legs of females, common in Negro with curly hair. After shaving the curly hair, the hair pierced the skin in stead of growing perpendicularly causing mechanical irritation and papulopustular lesion. Furunculosis (boils) • Deeply seated folliculitis affects the follicles as well as the dermis forming peirfollicular abscess. So painful, red nodules with discharging points of pus, could lead to scarring, the collection of boils form carbuncle with multiple drainage sites. carbuncle Folliculitis • Staph infection usually seen in itchy conditions like scabies, pediculosis and eczema, when there is skin injury from itching facilitate the entry of the staph , also in a person who is a carrier of staph ( 20% of population ) in the anterior naris , perineum and axilla. • Treatment of all types: - • For few lesions in localized area: antiseptic as potassium permanganate. • - Topical antibiotic, mupirocin (bactoban), neomycin, tetracycline and fucidic acid. • - If multiple lesions and wide spread infection: systemic and topical antibiotics; fluxacillin, cloxacillin and third generation cephalosporin. • - Surgical drainage. Ecthyma • Is an ulcerative deep staph or strepto pyoderma , nealy always of the shins or dorsal feet , tend to heal after few weeks , leaving scars . An uncleanliness, malnutrition and trauma are the predisposing causes , treatment by topical and systemic antibiotics. Erysipelas • An acute β – hemolytic group A -streptococcal infection of the skin involving the superficial dermal lymphatics, the face and the leg are the most frequent site affected. • Characterized by local tenderness, heat, swelling and a highly characteristic raised indurated border. Preceded by severe constitutional symptoms; chill, high fever, headache and vomiting. • Treatment by systemic penicillin continued at least for ten days. Local ice bag and cold compresses. Cellulites • Is a suppurative inflammation involving particularly the subcutaneous tissues caused most frequently by the strepto pyogens or staph aureus , it may affects any part of the body and may be associated with injury or surgical incision characterized by erythema and diffuse swelling and tenderness with no visible demarcation associated with chill and fever. • Treatment therapy should cover both streptococcal and staphylococcal infection. Scarlet fever • Erythematous exanthema occurs during coarse of streptococcal pharngitis manifest as tonsillitis strawberry tongue, punctuate erythema of the trunk and facial flushing, circumoral pallor, fallowed by peeling of hand and feet 1 week after • Treatment by penicillin Necrotizing fascitis • Acute necrotizing infection of fascia fallow surgery, perforating trauma, or denovo. Many virulent bacteria have been cultured (beta hemolytic strepo, hemolytic staph, and pseudomonas • Treatment: Intravenous antibiotics, surgical debridement Cutaneous tuberculosis • Caused by mycobacterium TB that can infect lung as well as other systems including the skin • There are 4 major categories of cutaneous tuberculosis. 1.Inoculation from an exogenous source (primary inoculation TB and TB verrucosa cutis). 2.Endogenous cutanous spread (auto inoculation), scrofuloderma, TB cutis orificialis. 3.Haematogenous spread to the skin (lupus vulgaris), acute military TB, TB ulcer, gumma or abscess. 4.Tuberculids: skin eruption associated with TB else where, example erythema induratum ( bazin’s disease) , papulo necrotic tuberculid , lichenscrofulosorum. 1/ Lupus vulgaris • Typically appear as single plaque composed of grouped red-brown papules which when blanched by diascopic pressure , have an apple jelly color mainly occurs on head and neck in a person with high degree of immunity , it is slowly progressive , destructive disease leaving deformed scar. 2/Scrofuloderma • Direct extension from underlying tuberculous lymphangitis, most frequently of cervical LN, so multiple nodules drain to form sinuses or ulcerate and heal with characteristic cord like scars. Scrofuloderma 3/ Tuberculosis verrucosa cutis • Common in butchers that deal with infected meat or affect anatomist dealing with infected cadavers, appear as hyperkeratotic plaques on the hands and feet. 4/ Primary inoculation TB (tuberculous chancre) • A nodule develops at site of inoculation of tubercle bacilli into a tuberculosis free individual that are neither immunized nor exposed to micro organism, which may ulcerate like syphilitic chancre and usually heal spontaneously with no treatment. 5/ Tuberculoids • Is a rare condition that is hypersensitivity reaction of the skin to TB bacilli infection else where in the body and the skin biopsy show no bacilli. • Erythema induratum (bazin’s disease ) multiple deep purplish ulcerating nodules that heal with scarring occur on the calf of middle aged obese women . • Papulo necrotic tuberciloid recurrent crop of ulcerative papules at the tips of the elbow and the knees heal by varioliform scarring 6/Tuberclosis cutis orificialis • involve the mucocutaneous border of the nose, mouth, anus, urinary meatus, and the vagina. Treatment of TB • Multi drug chemotherapy • - INH (isoniazid) 300 mg /day plus rifampicine 300 mg per day plus pyrazinamid 2 gm / day for 2 months then INH and rifampicine continued for other 7 months. • - Surgical draining for scrofuloderma • - Surgical excision for localized hyperkeratotic lesions. Leprosy • It is caused by mycobacterium leprae, weak acid fast bacilli, it is grow best at temperature between 32-35 C that why it may cultured in armadillos, the route of transmission of the infection from man to man is through respiratory route (nasal droplets) characteristically the disease affect skin and nerve, depending on the immunological status of the patient the disease either:- tuberculoid leprosy • : one or few lesions asymmetrically distributed , occur in patients with high immunity , positive lepromine test , associated with early prominent nerves involvement. The lesions are large erythematous or hyopigmented hairless anesthetic and anhydrotic plagues in which the organism are absent or few in the lesion Lepromatous leprosy • a numerous small contagious lesions (have a number of bacteria) symmetrically distributed, occurs