DERMATOLOGY BACTERIAL INFECTION Assistant Professor Mohammed yassin
The surface of the skin teems with micro-organisms which are most numerous in moist hairy areas rich in sebaceous glands . the resident flora is a mixture of harmless and poorly classified staphylococci , micrococcus , and diphtheroids. Infection caused by Gram – positive organisms …The 2 Gram – positive cocci , staphylococci aureus and group A. Beta – hemolytic streptococci , account for the majority of the skin and soft tissue infections . The streptococci are secondary invaders of traumatic skin lesions and cause impetigo , erysipelas, cellulites .S. aureus invades skin and cause impetigo , folliculitis , cellulites and furuncles. Elaboration of toxins by S. aureus causes the lesion of bullous impetigo and staphylococci scalded skin syndrome .
staphylococcal infection… Impetigo contagiosa :- is a staphylococci , streptococci or combined infection , it is common ,contagious superficial skin infection .There are two different clinical presentation : bullous impetigo and non - bulous impetigo. bullous impetigo is primary staphylococci disease . non - bullous is primary streptococci and now also staphylococci . non - bullous impetigo :- occurs in children with close physical contact with each other . Common sources are pets , dirty finger nails crowded houses .The disease begins with 2 –mm erythematous macules which shortly develop into vesicles or bullae . As soon as these lesions rupture , thin straw colored , seropurulent discharge .The exudate dries to form loosely stratified golden – yellow crusts , which accumulate layer upon layer until they are thick and friable .
Complications :- acute glomerulonephritis ( AG) Nephritogenic streptococci are generally associated with impetigo rather than upper respiratory infection . Differential diagnosis :- 1. Herpes simplex may be impetiginized as may . 2. Eczema . 3. Recurrent impetigo of the head and neck prompt search for head lice . 4. Ringworm infection . Bullous impetigo :- this variety characteristically occurs in new born infants . though it may be occur at any age , it is highly contagious and is a threat in nurseries . it begins between fourth and tenth days of life with the appearance of bulla . Common sites are face and hands . Constitutional symptoms are at first absent , but later weakness and fever . or subnormal temperature may be present .diarrhea with green stools frequently occurs.
Complications :- pneumonia – bacteremia – meningitis may develop rapidly , with fatal termination – osteomylitis ,& septic shock . Treatment :- * systemic antibiotics combined with topical therapy are advised .* Because most cases are caused by staph . Semi synthetic penicillin or a first generation cephalosporin .* All treatment should be given for 7 days .* it is necessary to soak off the crust frequently , after which bacitracin or mupirocin ointment should be applied .* applying antibiotic ointment as prophylactic to sites of skin trauma will prevent impetigo in high risk children . Staphylococcal Scalded Skin Syndrome ( ssss) :- is generalized , superficially exfoliative , confluent disease occurring most commonly in neonates and young children .- ssss is generally febrile , rapidly evolving , generalized , desquamative infectious disease , in which the skin exfoliates in sheets . the skin separate at the granular layer .
Clinically :-* begin abruptly with fever , skin tenderness and erythema involving the neck , groins ,and axilla .There is sparring of the palms and soles and mucous membranes .* nickolsky sign is positive .* Generalized exfollation follows with in the next hours – days with large sheets of epidermis separating .Diagnosis :- * Rapid dignosis can be made by examining the frozen sections of ablister roof .* Cultures are taken from the mucous membranes .DDx: TEN(toxic epidermal necrolysis),BurnTreatmeant :- Penicillinase resistant penicillin such as dicloxacillin combined with fluid therapy and general supportive measures .Prognosis :- is good in children .
Folliculitis :- ** superficial pustular follicutlitis (impetigo of bockhart ) :-* is a superficial follicutlitis with thin walled pustules at the follicle orifices .* Favorite locations are extremities and scalp , it is also seen on the face , especially periorally .* Fragile yellowish – white domed pustules develop in crops and heal in few days .* staph. Aureus is the most frequent cause .* it may secondarily arise scratches , insect bites , or other skin injuries .** Sycosis Vulgaris (sycosis barbae ) :-* is a perifollicular , chronic , pustular staphylococcal infection of the bearded region .* characterized by the presence of inflammatory papules and pustules and tendency to recurrence .* The disease begins with erythema and burning or itching usually on the upper lip near the nose . in day or two one or more pin – head pustules pierced by hairs develop.* These ruptures on shaving or washing leave erythematous spots .
Complication:- * spread. * scar formation * marginal blepharitis with conjunctivitis . DDX :- Tinea Barbae, acne vulgaris , pseudofolliculitis barbae and herpetic sycosis . Follicutlitis in other areas :- Staph . folliculitis may occur in eyelashes , axillae , pubis and thighs. On the pubis it may be transmitted among sexual partners. Treatment of follicutlitis:- * A thorough cleaning of the affected areas with antibacterial soap and water three times a day is recommended . * Deep lesions represent small follicular abscess and must be drained . * Many patients will heal with drainage and topical therapy . * bacteroban ( mupirocin )and retapamoline ointment and topical cleocin . * If the above fail , first generation cephalosporin or penicillinase resistant penicillin . such as dicloxacillin is indicated . When the inflammation is acute , hot , wet soaks with burrow solution .
Furunculosis:- furuncule or boil is an acute , round ,tender ,circumscribed , perifollicular staphylococcal abscess that generally ends in central suppuration . ** Acarbuncie :- is a merely two or more confluent furuncles , with seperate heads. * The lesion begins in hair follicles , and often continues for prolonged period by autoinoculation. * Some lesions disappear before rupture , but most undergo central necrosis and rupture through the skin , discharging purulent , necrotic debris . * Site of predilection :- nape of neck , axillae , and buttocks but boils may occur anywhere .
Risk factor :- * Irritated skin , pressure ,friction , hyperhydrosis . * Dermatitis ,Dermatophytoses or shaving . * Certain systemic disorders may predispose to furunculosis alcoholism , malnutrition blood dyscrasias , and disorders of neutrophil function , immuno suppression ,AIDS and diabetes . Treatments :- * Warm compresses and antibiotics taken internally may arrest early furuncles . * A penicillinase resistant penicillin or first generation cephalosporins should be given orally in a dose of 1 -2 g day. * When the lesions are early and acutely inflamed incision should be strictly avoided and moist heat employed .
Prevention
to break the cycle of recurrent furunculosis 1- a daily chlorhexidine wash, with special attention to the axillae, groin, and perianal area 2- laundering of bedding and clothing 3- use of bleach baths; 4- frequent handwashing. 5- application of mupirocin ointment twice daily to the nares of patients and family members every fourth week has been found to be effective. 6- Rifampin (600 mg/day) for 10 days, combined with dicloxacillin for MSSAstreptococcal skin infections
Ecthyma :- Is an ulcerative stapylococcal or streptococcal pyoderma ,nearly always of the shins of the dorsal feet .* The disease begins with a vesicle or vesicopustule which enlarge to form in a few days thickly crusted lesion .* when the crust is removed there is superficial saucer – shaped ulcer with raw base and elevated edges .Risk factor :- * uncleanliness .* malnutrition and trauma . Treatment :-* cleansing with soap and water .* Application of mupirocin or bacitracin ointment twice daily .* Oral dicloxacillin or fist generation cephalosporin is also indicated .Prognosis:-The lesions tend to heal after a few weeks , leaving scars but rarely may proceed to gangrene .** Scarlet Fever :-is a diffuse erythematous exanthema that occurs during the course of streptococcal pharyngitis . The eruption is produced by erythogenic extotoxin .* It affect primarily children , who develop eruption 24 – 48 hr .after the onset of pharyngeal symptoms .* The tonsils are red , edematous and covered with exudates .* The tongue has a white coating through which reddened , hypertrophied papillae project giving appearance ( white strawberry ) .* By the fourth or the fifth day the coating disappear , the tongue is bright red , and the ( red strawberry tongue ) remains . The cutaneous eruption begins in the neck , spreads to the trunk , and finally the extremities .
* with in the widespread erythema are 1-2 papules which give the skin sand paper quality .* There is accentuation over skin folds .* There is facial flushing and circumoral pallor .* Abranny desquamation occurs as the eruption fades , with peeling of the palms and soles , about 2 – weeks after acute illness . The later may be the only evidence that the disease happened .Diagnosis :- * Culture of the pharynx will recover the organism .* Elevated antistreptolysin titer ( ASO titer ) may provide evidence of recent infection .Treatment :-Penicillin , erythromycin or dicloxacillin the treatment is curative .Prognosis :-The px is excellent .
** Celluiltis & Erysipelas :- are skin infection characterized by erythema ,edema and pain . in most instances there is fever and leukocytosis . ** Celiuiltis :- is a suppurative inflammation involving particularly the subcutaneous tissue caused most frequently by streptococcus pyogens or S.aureus . Risk facter :- Minor trauma or abrasions and psoriatic , eczematous or tinea lesions . on the leg tinea pedis is the most common portal of entry . * Mild local erythema and tenderness , malaise and chilly sensation and fever may be present at the onset . * The erythema rapidly becomes intense and spreads . The area becomes intense and pits on pressure . * Sometimes the central part becomes nodular surmounted a vesicle and discharge pus and necrotic martial .
Diagnosis :- * distinctive clinical . * isolation of the etiologic agent is difficult . * Fever with leukocytosis with mildly increased sedimentation rate . * Culture of the organism on needle aspirate specimens or blood culture . ** Erysipelas :- is an acute B- hemolytic streptococcal infection ( group A ) of the skin involving the superficial dermal lymphatics . Clinically :- * The skin lesions vary form transient hyperemia to slight desquamation , to intense inflammation with vesicles or bullae , * A distinctive features is the advancing edge of the patch , this is raised and sharply demarcated . * it feels like a wall to the palpating finger . * The leg and face are the most frequent sites affected .
Risk facter :- * Operative wounds . * Fissures . * Abrasions . * Unclean tying of umbilical cord . * Venous insufficiency . * Obesity . * lymphoedema * chronic leg ulcers . DDX :- * lupus erythematous . * contact dermatitis * angioneurotic edema . complications :- septicemia . deep cellulitis, necrotizing fasciitis, and abscess formation may be complications, especially in obese patients and those with chronic alcohol abuse.
Treatment :- * initial empiric treatment should be cover both staphylococci and streptococci . * intravenous penicillinase resistant penicillin or first generation cephalosporin is usually effective . * Treatment should be continued for at least 10 days . * Erythromycin is also effective . * locally ice bags and compresses are used
Infection Caused by over growth of aerobic diphtheroids
** Erythrasma :- A mild , chronic , localized , superficial infection of the skin caused by corynbacterium minutisimum . * characteristic by sharply demarcated ,dry , brown , slight scaling patches occurring in the intertriginous areas , especially the axillae , the genitocrural crease , and the webs between the fourth and the fifth toes and less commonly between the third and fourth toes . * The lesion is asymptomatic except in the groins , where may be some itching and burning . DDX :- Tinea cruris , intertrigo , seborrheic dermatitis , inverse psoriasis , candidiasis and lichen simplex chronicus .DX :- The woods light is the diagnostic medium for erythrasma which shows a coral red flouroscence which results from presence of porphyrin . Treatment :- * topical erythromycin or topical clindamycin is easily applied and rapidly effective . * Oral erythromycin 250 mg four times a day for 1 week , or tolnaftate solution or topical miconazole .
Toxic Shock Syndrome Introduction Toxic shock syndrome [TSS)is a multisystem disease caused by an exotoxin produced by S. aureus. Or strept Clinical features TSS is characterized by a sudden onset of high fever with myalgias, vomiting, diarrhea, headache and pharyngitis. Rapid progression to shock can occur. Clinically, the illness can vary from relatively mild disease to being rapidly fatal. The dermatologic manifestations are more extensive and predictable in staphylococcal TSS than in streptococcal TSS. Patients usually develop a diffuse scarlatiniform exanthem that starts on the trunk and spreads centripetally. There is erythema and edema of the palms and soles. Erythema of the mucous membranes, a strawberry tongue, hyperemia of the conjunctivae , and a generalized non-pitting edema are also present. Desquamation of the hands and feet occurs 1-3 weeks after the onset of symptoms.
Treatment Severe cases of TSS require intensive supportive therapy. Hypotension should be treated with intravenous fluids and vasopressor agents. Foreign bodies (e.g. meshes) and any nidus of infection (e.g. nasal packing, tampon) should be removed. Beta-lactamase-resistant antibiotics are used to eradicate any foci of toxin-producing staphylococci. Some advocate using antibiotics that suppress toxin production, such as clindamycin, rifampin or fluoroquinolones. In severe cases of shock unresponsive to antibiotics, low-dose corticosteroids have beenUsed.