MCB quiz 2 - MCB Skin and Nerve Infections SKIN Structure...

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MCB – Skin and Nerve Infections SKIN Structure of the Skin - Functions of the skin o Prevents excessive water loss o Important to temperature regulation o Involved in sensory phenomena o Barrier against microbial invaders - Composed of two main layers o Dermis o Epidermis - Wounds o Trauma to any tissue of the body From cuts and scrapes to surgery, burns, bites, etc. o Allow microbes to infect the deeper tissues of the body o In most cases other body defenses eliminate the infection o Can results in severe or fatal diseases Normal Microbiota of the Skin - Skin microbiota are normally harmless microbes able to survive on the skin o Cannot be completely removed through cleansing o Made up of various microbes The yeast, Malassezia The bacteria, Staphlycococcus, Micrococcus, and the diphtheroids o May produce disease, particularly if they penetrate epidermis or if immune system is suppressed Bacterial Diseases of the Skin and Wounds - Folliculitis o Signs and symptoms Infection of the hair follicle Often called a pimple Called a sty when it occurs at the eyelid base Spread of the infection into surrounding tissues can produce furuncles Carbuncles occur when multiple furuncles grow together o Pathogen and virulence factors Most commonly caused by Staphylococcus Bacteria that are facultatively anaerobic, gram-positive cocci, arranged in clusters Salt tolerant
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Tolerant of desiccation Two species commonly found on the skin Staphylococcus epidermidis Staphylococcus aureus o Diagnosis Detection of Gram-positive bacteria in grapelike arrangements isolated from pus, blood, or other fluids o Treatment Dicloxacillin (semi-synthetic form of penicillin) is the drug of choice for staphylococcal infections Vancomycin use to treat resistant strains o Prevention Hand antisepsis Also, proper cleansing of wounds and surgical openings, aseptic use of catheters or indwelling needles, and appropriate use of antiseptics - Staphylococcal Scalded Skin Syndrome o Pathogen and virulence factors Some Staph aureus strains One or two different exfoliative toxins cause SSSS o Pathogenesis No scarring because dermis is unaffected Death is rare but may occur due to secondary infections o Epidemiology Disease occurs primarily in infants Transmitted by person-to-person spread of bacteria o Diagnosis, treatment, and prevention Diagnosed by characteristic sloughing of skin Treated by administration of antimicrobial drugs Difficult prevention due to widespread occurrence of S. aureus - Impetigo (Pyoderma) and Erysipelas o Pathogens and virulence factors Most cases caused by S. aureus Some cases caused by Streptococcus pyogenes (often called Group A Streptococcus Gram-positive coccus, arranged in chains Virulence factors similar to those of S. aureus o M protein interferes with phagocytosis o Hyaluronic acid acts to camouflage the bacteria o Pyrogenic toxins stimulate fever, rash, and shock
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This note was uploaded on 04/07/2011 for the course MCB 158 taught by Professor Kaplan during the Spring '11 term at Saint Louis.

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MCB quiz 2 - MCB Skin and Nerve Infections SKIN Structure...

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