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.

n 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.

n 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).

n 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

n 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

n 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.

n The stages of Ecthyma: The lesion begins as a pustule that later erodes and ultimately forms an crusty dermal ulceration. Ecthyma of lower extremities.

N 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.

n 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.

n 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.

n -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 years of age. -Staphylococcus aureus is the most common cause. -Predisposed people are obese, diabetic, or with weak immunity.

n 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.

n 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.

n Cellulitis: Possible signs and symptoms include: -Redness -Swelling -Tenderness -Pain -Warmth -Fever Risk factors include: Lymphedema Staphylococcus cellulitis and Bullous History of cellulitis Intravenous drug use Obesity Weakened immune system Skin conditions

n Staphylococcus cellulitis and Streptococcus cellulitis. Invasive Group A Streptococcus cellulitis

n 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.

n 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 mellitus 2-Cancer 3-Vascular insufficiencies -Two types: 1- Type I: Describes a Polymicrobial infection. 2-Type II: Describes a Monomicrobial infection.

N 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).

N 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 collapse Scarring with limb deformity or loss Toxic shock syndrome and Septicemia Extensive muscle necrosis. Antibiotic therapy and Surgical intervention: Combination of penicillin G and an aminoglycoside.

N Necrotizing Fasciitis:

N 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

n Causes of Acne vulgaris: Hormonal Genetic Psychological Diet Infectious Agent Propionibacterium acnes Staphylococcus epidermidis