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Skin, and Soft Tissue Infections:
Impetigo:-Impetigo is Superficial localized epidermis-skin infection.
-Caused by Streptococcus or Staphylococcus bacteria.
-Most common in children; particularly those in unhealthy living conditions.
-Impetigo is highly contagious: -The fluid that oozes from the blisters touches other skin site. -Types of impetigo: 1-Nonbullous impetigo. 2-Bullous impetigo.
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1-Non-bullous impetigo:-It begins as small vesicles that rupture quickly to form purulent erosions covered by honey-colored, adherent thick crusts.-Usually on face and extremities.-Lesions are superficial and limited to the epidermis, and are usually painless but may itch.
-Staphylococcus aureus accounts for 50-60% of cases.-About 20-45% of cases are due to a combination of Staphylococcus aureus and Streptococcus pyogenes.
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Clinical presentation of Non-bullous impetigo:
Staphylococcus impetigo Streptococcus impetigo
-Swab could be taken from lesions for detection of MRSA.-The sores of impetigo heal slowly and seldom scar.-Permanent skin damage and scarring (very rare).
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2-Bullous impetigo:-Large superficial fragile blisters filled with pus that rupture to leave a reddish raw-looking base lesion. -Caused by epidermolytic toxin-producing strains of Staphylococcus aureus.
-Painless Lesions on the face, arms, or legs, and other.
-Itching single or multiple blister(s):-Yellow or honey-colored fluid-Oozing and crusting over
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Bullous impetigo fluid-filled blisters are surrounded by red (erythematous) and itchy skin.
-Mainly seen in children younger than 2 years (about 90% of cases).
In Non-Bullous and Bullous impetigo:-Person-to-person transmission occurs in people living in crowded conditions and with poor hygiene.-Complication: Post-Streptococcus glomerulonephritis. Bullous impetigo
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Ecthyma: (deep impetigo):-It is an ulcerative form of impetigo that extends deeper into the dermis.-It begins as a vesicle or pustule overlying an inflamed area of skin that deepens into a dermal ulceration with overlying crust.-The crust is gray-yellow and is thicker and harder than impetigo crusts. -Ecthyma is most often caused by Streptococcus species.
-The infection may start in skin that has been injured due to a scratch or insect bite.
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The stages of Ecthyma:The lesion begins as a pustule that later erodes and ultimately forms an crusty dermal ulceration . Ecthyma of lower extremities.
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Folliculitis: -It is a purulent bacterial infection of the hair follicle.-Appears as a pinhead-sized erythematous papule topped by a superficial pustule located at the orifice of the hair follicle. -Staphylococcus aureus is the most common causative agent.
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Furunculosis :(Boils):
-Painful focal (localized) purulent (Filled with pus)
inflammatory lesion of skin; within dermis due to
uncontrolled folliculitis and sebaceous glands infection.
-This Micro-abscess show a progressive local swelling and
erythema.
-Staphylococcus aureus
is the most common
cause.
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Carbunculosis: -Larger and deeper purulent skin abscess of multifocal origin in deep dermis with multiple sinus tracts.-It is a number of furuncles connected together by sinus tracts.-It can be complicated by bacteremia.
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-The purulent lesions often rupture spontaneously and drain a purulent matter (mainly neutrophils), bringing immediate relief of pain. -Boil Lesions can occur anywhere on hair-bearing skin.
-Carbuncles are usually found in the thick fibrous inelastic skin of the neck and upper back.-Seen in 15-40 years of age.-Staphylococcus aureus is the most common cause.-Predisposed people are obese, diabetic, or with weak immunity.
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Erysipelas:
-Infection in upper dermis layer of skin characterized by
diffusely spreading deep-erythematous and
edematous inflammation.
-Especially in the face or legs.
-The infection spreads in the superficial
lymphatics of the dermis.
-80% of cases are due to Streptococci, 2/3 of these are
due to Streptococcus pyogenes.
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Cellulitis: -Deep diffused inflammation of dermis and subcutaneous layer of skin without necrosis.
-Streptococcus pyogenes and Staphylococcus aureus are the most common causative agents: (Superantigen and exfoliative toxins).
-Gram’s negative bacilli (E.coli, Pseudomonas) cause superficial cellulitis results in granulocytopenia and foot ulcer in diabetic patients.
-The spreading infection may rapidly turn life-threatening, due to lymph node invasion and bacteremia.
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Cellulitis:Possible signs and symptoms include: -Redness -Swelling -Tenderness -Pain -Warmth -FeverRisk factors include:
Lymphedema Staphylococcus cellulitis and Bullous
History of cellulitis Intravenous drug useObesityWeakened immune systemSkin conditions
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Staphylococcus cellulitis and Streptococcus cellulitis.
Invasive Group A Streptococcus cellulitis
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Complications of Cellulitis: 1-Bacteria can spread rapidly throughout body entering lymph nodes and bloodstream. (Lymphadenitis, Bacteremia, or Septicemia).
2-Recurrent cellulitis due to damaged lymphatic drainage system.
3-In rare cases: -Infection spread to the deeper layer of tissue the fascial
lining causing necrotizing fasciitis.
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Necrotizing Fasciitis: "Flesh-eating bacteria"
-A rapidly progressive deep diffused inflammatory infection
of the fascia, with secondary necrosis of the subcutaneous
tissues.-Frequency of necrotizing fasciitis linked to an increase in:
1-Diabetes mellitus2-Cancer3-Vascular insufficiencies
-Two types:
1- Type I: Describes a Polymicrobial infection.
2-Type II: Describes a Monomicrobial infection.
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Type I : Polymicrobial infection:
-It is associated with Staphylococcus aureus, Streptococcus
pyogenes, other like Vibrio species, Bacteroides fragilis,
and Clostridium perfringens.
Type II: Monomicrobial infection:
-It is mainly caused by Group A Streptococcus or
methicillin-resistant Staphylococcus aureus (MRSA).
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Necrotizing Fasciitis:-Rapid progression of severe pain with fever, and chills
-Swelling , redness, hotness, blister, gangrene and necrosis
-Blisters with subsequent necrosis, and Organ failure
-Mortality as high as 73 % if untreated
Complications:Renal failure, Septic shock with cardiovascular collapseScarring with limb deformity or lossToxic shock syndrome and SepticemiaExtensive muscle necrosis.
Antibiotic therapy and Surgical intervention: Combination of penicillin G and an aminoglycoside.
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Acne vulgaris:-It is a disease that significantly affects most teenagers worldwide.-Several different types of acne lesions exist and include open or closed comedones, inflammatory papule, pustules, and nodule. -Limited to face, upper chest, and back.-Whitehead (closed) comedo.-Blackhead (open) comedo. -Acne affects mostly skin with the densest population of sebaceous follicles
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Causes of Acne vulgaris:Hormonal
Genetic
Psychological
Diet
Infectious AgentPropionibacterium acnesStaphylococcus epidermidis