PowerPoint ??PPT fileWeb view2017-09-24... 2 Verdana Calibri Symbol Verve 1_Verve 2_Verve 3_Verve 4_Verve 5_Verve 6_Verve Wound Infections Slide 2 Wound Infections Staphylococcal Wound Infections Staphylococcal Wound Infections Staphylococcal Wound

Download PowerPoint  ??PPT fileWeb view2017-09-24... 2 Verdana Calibri Symbol Verve 1_Verve 2_Verve 3_Verve 4_Verve 5_Verve 6_Verve Wound Infections Slide 2 Wound Infections Staphylococcal Wound Infections Staphylococcal Wound Infections Staphylococcal Wound

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  • Penetration of the skin by micro-organisms is difficultPart of the innate defenseWounds provide the most common access through the skin.Disease production in infected wounds depends onHow virulent infecting organisms areHow many organisms infect the woundIs the host immunocompetentNature of the wound

    Does it contain crushed material or foreign material

  • Leading cause of wound infectionsSymptomsBacteria are pyogenicInfection causes

    Inflammation

    Fever

    Some strains produce toxic shock syndromeMore than 30 recognized strains

  • Causative Agent: S. aureus

    Virulence due to the production of extracellular products

    Coagulase

    Causes blood clotting to evade phagocytosis

    Clumping factor

    Aids in bacterial wound colonization

    Protein A

    Hide bacteria from phagocytic cells

    toxin

    Produces hole in host cell membrane

  • TreatmentMany strains develop resistance to antibiotics

    Many strains treated with anti lactamase penicillins and vancomycin

    Vancomycin resistant strain identified in 1997

    Epidemiology

    30% to 100% due to patients own flora

    Factors associated with infection include

    Advanced age

    Immunosupression or poor general health

    Prolonged postoperative hospital stay

  • Primary pathogen is S. pyogenes Also known as flesh eaters

    hemolytic, Gram-positive cocci in chains

    Can cause rapidly deteriorating disease and deathCommon cause of wound infectionsNot a lot of antimicrobial resistance: early penicillin

    Two extracellular products are responsible for virulencePyrogenic exotoxin Asuperantigen : toxic shockExotoxin Bnecrotizing fasciitis

  • P. aeruginosaMajor cause of nosocomial infectionsLung infectionsBurn infectionsCommunity acquired infections includeRash and external ear infectionsInfection of foot bones Eye infectionsHeart valve infectionsLung biofilms

  • PathogenesisSome strains produce enzymes and toxins to enhance virulence

    Exoenzyme S

    Toxin A

    Phosphlipase C

    EpidemiologyP. aeruginosa is widespread in naturePrevention and TreatmentPrevention involves elimination of sources of bacteriaP. aeruginosa is multi-drug resistantMedications must be administered intravenously at high doses

  • SymptomsDivided into early and late symptomsEarly symptoms

    Restlessness

    Irritability

    Difficulty swallowing

    Contraction of jaw muscles

    Convulsions

    Particularly in children

    Later symptoms

    Increased muscle involvement

    Pain

    Difficulty breathing

    Death

  • Causative AgentClostridium tetini

    Anaerobic

    Gram-negative

    Bacillus

    Spore former

    25% mortality rate; rare in the developed worldtetanospasmin toxin

    blocks inhibition of motor neurons, causing paralysis

    Prevention: vaccination, treatment: antitoxin

    Bacterial spores prevalent in dirt and dust and gastro intestinal tract of humans and other animals

  • Causative AgentSeveral species of Clostridium

    Most common offender, C. perfrigens

    Encapsulated, Gram-negative bacillus

    Endospores of causative bacillus are innumerable Spores found in nearly all soil or dusty surfaceNormal flora of intestinal tract and vaginaPrimarily disease of wartimeDue to neglected wounds containing debrisTreat with hyperbaric oxygen, antibiotics (penicillin)

  • Causative AgentActinomyces israelii

    Filamentous, anaerobic, slow growing

    PathogenesisA. israelii cannot penetrate healthy mucosaInfection is characterized by cycles

    Abscess formation scarring formation of sinus tracts

    Disease progresses to skin and can penetrate bone or central nervous systemEpidemiologyCan be normal floraPrevention and TreatmentNo proven preventionResponds to numerous antibacterials

    Penicillin and tetracycline

  • Causative AgentPasteurella multocida

    Gram-negative

    Coccobacillus

    Rounder bacillus shape

    Most are encapsulated

    Bite infections from numerous animalsFowl Cholera, animal reservoirSymptomsSpreading redness TendernessSwelling of adjacent tissuesPus discharge

  • Causative AgentBartonella henselae

    Gram-negative bacillus

    SymptomsDisease begins within a weekPainful enlargement of lymph nodesFever EpidemiologyZoonotic disease

    Cats infected by flea bite

    Infections treated with amipicillin

  • Causative AgentStreptobacillus moniliformis

    Gram-negative,Bacillus

    SymptomsBite wound usually heals without complicationDevelopment of chills, fever, head and muscle ache and vomiting 2 to 10 days after healing

    Majority of cases are self limiting

    7% - 10% of untreated cases are fatal

  • Causative AgentSporothrix schenckii

    Dimorphic fungus

    Lives in soil and on vegetation

    Associated with puncture wound from vegetationSporadic: rare in healthy peopleUntreated cases may become chronicItroconazole and amphotericin B

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