Skin And Soft Tissue Infections

SKIN AND SOFT TISSUE INFECTIONS

SUBJECT TOPIC LECTURER TRANSGROUP Skin anatomy

Hair follicle - can serve as portal of 1. components of the normal flora e.g. staphylococcus 2. extrinsic bacteria pseudomonas in the hot tub folliculitis Plexus of capillaries 1. infective vasculitis of the plexus results in petechiae, osler’s node, purpura 2. metastatic infections of the plexus can results in the cutaneous manifestation of disseminated fungal infection, gonoccocal inf, salmonella inf, meningococcemia, pseudomonas and staphylococcal infections

Cellulitis - an acute inflammatory condition of the skin characterized by localized pain, erythema, swelling and heat - Etiologic agent • staph Aureus and staph pyogenes; streptococcus, A, C or G; Haemophilus influenza; - CLINICAL FEATURES a. Cellulitis of the lower extremities Grp A, C, G streptocci in association with chronic venous stasis or saphenous venectomy b. cellulitis from patient ith chronic lymphedema, lymph node dissection are due to streptococci c. cellulitis caused by grp B streptocci occurs primarily with the elderly patients or those with diabetes mellitus or those with peripheral vascular disease. d. H. influenza typically causes periorbital cellulitis in children e. cellulitis associated with cat’s bite is due to Pasteurella Multocida while dogbite cellulitis is due to Capnocytophagia canimorsus f. P. aeroginosa causes ecthyma gangrenosum in neutropenic patient hot-

tub follicolitis, cellulitis following penetrating injury g. cellulitis due to gram negative bacillary are common among hospitalized, immunocompromised hosts Treatment a. Dicloxacillin, nafcillin b. Ampicillin/clavunate, ampicillin/sulbactam and erythromycin c. Quinolones, tetracylines, and erythromycin d. Third generation cephalosphorinceftazidime, cefotaxime e. Semisynthetic penicillinticarcillin, mezlocillin, piperacillin Folliculitis Localized folliculitis - are caused by staphyloccus aureus Hot-tub folliculitis - are caused by P. aeroginosa in the waters that were insufficiently chlorinated Necrotizing Fascitis or fasciitis necroticans commonly known as “flesh-eating bacteria” is a rare infection of the deeper layers of skin and subcutaneous tissue, easily spreading across the fascial plane within the subcutaneous tissue - Many types of bacteria can cause necrotizing fasciitis (eg. Group A staphylococcus, Vibrio vulnificus, Clostridium perfringens, Bacteroides fragilis), of which Group A streptococcus (also known as streptococcus pyogenes) is the most common causes. - “Flesh-eating bacteria” is a misnomer, as the bacteria do not actually eat the tissue. - They cause the destruction of the skin and the muscle by releasing toxins (virulence factors). • These include streptococcal pyogenic exotoxins and the other virulence factors. S. pyogenes produces an exotoxin known as superantigen. This toxin is capable of activating T-cells non-specifically. This causes the overproduction of cytokines. a. formerly called streptococcal Gangrene caused by S. Pyogenes, Clostridium species mixed aerobic and anaerobic resulting to gas gangrene

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Stratum corneum - Infection can sets in thru the following: 1. disruption of this layer by burns, abrasion, surgery, bites, vascular ulcer 2. primary dermatologic disorders- herpes simplex, varicella, etchyma

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SUBJECT TOPIC LECTURER TRANSGROUP

Treatment Early recognition and surgical interventions and appropriate empiric antibiotic combination with Clindamycin or Metronidazole + Ampicillin/ sulbactam or Gentamycin c. Necrotizing Fasciitis affecting the gastrointestinal and genitourinary tract might result from malignancy, diverticulum, haemorrhoid or anal fissure as portal of entry d. Fournier’s gangrene syndrome resulted from a leakage in the perianal area affecting the massive swelling of the scrotum and penis with extension to the perineum or the abdominal wall and the leg Bullae Staphyloccal scalded-skin syndrome  Staphyloccal aureus Blistering distal dactylitis  S. aureus or strep pyogenes Necrotizing Fasciitis  S. pyogenes, Clostridium spp. anaerobes-aerobes Gas gangrene  clostridium spp

Mixed

Staphyloccal scalded-skin syndrome - is seen neonates caused by a toxin (exfollatin) from phage grp II S. aureus affecting stratum corneum Gas Gangrene • the most offending organism is clostridium spp but the predominance of Cl. Perfringes to cause gas gangrene are often seen • clostridium perfingens possesses at least 17 possible virulence factors including 12 active tissue toxins and enterotoxins affecting the gastrointestinal colonic flora or the female genital tract area. Clinical presentations of Cl. Perfingens may be in the form of: a. food poisoning due to cytotoxins b. necrotizing enterocolitis c. neutropenic enterocolitis

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Cl. Difficile can cause antibiotic associated colitis also known as Pseudomembranous Colitis where the stools are watery, voluminous with blood and mucus.

Gangrene is a complication of necrosis (i.e., cell death) characterized by the decay of body tissues, which become black and malodorous. It is caused by infection or ischemia, such as from thrombosis ( blocked blood vessel). It is usually the result of critically insufficient blood supply (e.g. peripheral vascular disease). It is usually the result of critically insufficient blood supply (e.g. peripheral vascular disease) and is often associated with diabetes, and long term smoking. This condition is the most common in the lower extremities Clinical Manifestations Skin & soft tissue infections- various categories of traumatic wound infection due to clostridia have been describe; simple contamination, anaerobic cellulitis, fasciitis with or without systemic manifestations and anaerobic myonecrosis that includes diabetic foot. Incubation period of gas gangrene - is usually short almost always less than 3 days and frequently 24 hrs. - typically, it begins with the sudden onset of pain in the region of the wound - frothiness of the wound exudates may be noted Diagnosis • Positive Clostridia in cultures from wound exudates, scrapings, cervical discharges showing gram-positive rods • Wright or Gram’s stain of smear of peripheral blood may show in severe sepsis from clostridia • X-ray exam may show gas in the muscles, subcutaneous tissues or other organs affected but not specific only for clostridium • ELISA can identify the toxins A of C. Difficile exhibiting specificity but lower sensitivity by 70-90%. • Stool culture however, for C. difficile may be difficult to obtain but production of the toxin is the hallmark of disease.

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b. If the infection is due to mixed anaerobic-aerobic may be associated with gas in deep tissues

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The best treatment for gangrene is revascularization (i.e. restoration of blood flow) of the affected organ, which can reverse some of the effects of necrosis and allow healing. Other treatments include debridement and local care, or surgical amputation. The method of treatment is generally determined depending on location of affected tissue and extent of tissue loss. Gangrene may appear as one effect of foot binding.

Varicella Zoster Virus Introduction Varicella or chicken pox, is extremely a contagious infection, is usually a benign illness of childhood characterized by an exanthematous vesicular rash. With reactivation of latent VZV (which is most common after six decade of life), herpes zoster presents as dermatomal vesicular rash. Usually associated with severe pain known as Post-herpetic neuralgia (PHN) Pathogenesis Primary infection - due to varicella virus affecting children between 1-4 yrs old or 10-14, very contagious Recurrent infection - presumably the virus infects the dorsal root ganglia during chickenpox where it tremains latent until unreactived. Clinical Manifestations • Incubation period- 14-17 days • Children are mostly affected age between 5-9 yrs but some countries even beyond 15 yrs are also affected. • Clinically, chickenpox presents as rash, low grade fever, and malaise. • The hallmark of the infection include maculopapules, vesicles and scabs in various stages in evolution Diagnosis Tzanck smear

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scrapings of the base of the lesion to demonstrate the giant multi-nucleated cells Tissue Culture Cell-lines - to demonstrate the VZV PCR - to detect the viral DNA from vesicular fluids FAMA (fluorescent Antibody to Membrane Antigen) and ELISA - serologic tools for assessing host response PROPHYLAXIS Varicella-Zoster Immune Globulin (VZIG) & Varicella Immune Plasma (ZIP) should be given within 72 hrs of exposure to ensure efficacy Treatment

Acyclovir 800mg by mouth five times a day for 5-7 days

Papular and Nodular Lesions Shistosomiasis - multiple erythematous papules Lepromatous Leprosy - thickened subcutaneous tissue Secondary Syphils - flat papulosquamous lesions Tertiary syphilis - large nodules or gummae Human Papillomavirus - can cause singular warts (VV) Ulcers with or without eschar Decubitus ulcers - this skin infection is due to tissue hypoxia secondary to pressure-induced vascular insufficiency and may become secondarily infected with components of the skin and gastrointestinal flora, including anaerobes. Erysipelas - Infection of the face and extremities due to S. pyogenes showing a fiery-red swelling - Its distinct features are well defined indurated margins along the nasolabial fold, rapid progression and intense pain - Flaccid bullae may develop during the 2nd and 3rd day of illness, rarely extend to deeper soft tissues - Treatment with Penicillin is effective

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Treatment • Antibiotic combination of clindamycin and penicillin G for severe sepsis while for diarrhea cause by Clostridia, metronidazole is the drug of choice. Treatment must be 10-14 days to avoid relapse of the infection.

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SUBJECT TOPIC LECTURER TRANSGROUP Infants and elderly adult are most commonly afflicted

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Medicine (June 23, 2008) Skin and Soft Tissue Infections Dr. Gabriel Paolo Paraiso Fans Club