Chapter 21 Answers – Flashcards
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| nutrients for some organisms on the skin |
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| sebum and perspiration |
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| inhibits pathogens on the skin |
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| fatty acids and lysozyme |
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| when they live on skin the are resistant to what |
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| desiccation and high concentrations of salt. Staphylococci and micrococci. |
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| propionibacterium |
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| metabolize oil from the oil glands and colonize hair follicles. gram positive rods. reduce the skin pH to 3-5 |
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| corynebacterium xerosis |
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| aerobe comonly found inhabiting skin surface |
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| malassezia sp |
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| yeast that grows on oily secretions and thought to be responsible for scaling condition of dandruff |
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| staphylococcus epidermidids |
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| majority of skin microbiota. not pathogenic unless in a cut. 90% of flora |
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| staphylococcus aureus |
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| can produce golden colonies, ?-hemolysis, several toxins and extracellular factors responsible for virulence. |
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| s. aureus produces proteins and toxins that |
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| prevent phagocytosis, immobilize neutrophils, kill phagocyte (neutrophils), form clots, |
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| pathogeniticty island |
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| large insert of DNA not found in S. epidermidis, encodes many of the virulence traites unique to S.aureus. |
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| S. toxemias diseases |
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| include scalded skin syndrome and toxic shock syndrome |
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| toxic schock syndrome symptoms |
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| life threatening condition, brings on fever, vomiting, organ failur (esp. kidney) and rash. |
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| folliculitis |
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| infections of the hair follicles |
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| sty |
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| folliculitis of an eyelash |
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| furuncle |
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| abscess, pus surrounded by inflamed tissue |
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| carbuncle |
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| inflammation of tissue under the skin. |
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| impetigo |
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| crusting (nonbullous) sores, spread by autoinoculation |
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| group A beta-hemolytic streptococci |
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| pathogens most frequently associated with disease. |
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| group A beta-hemolytic streptococci virulence factors |
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| M protein, erythrogenic toixin, deoxyribonuclease, streptokinases, hyaluridinase, streptolysisns and hyaluronic acid capsule |
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| m protein |
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| involve in adherance and complement activation and phagocytic avoidance |
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| deoxyribonuclease |
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| degrades DNA |
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| streptoinases |
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| dissolve blood clots |
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| hyaluridinase |
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| degrades connective tissue |
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| streptolysins |
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| lyse red blood cells and poison neutrophils |
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| hyaluronic acid capsule |
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| antiphagocytic; masks bacterium due to resemblance to connective tissue |
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| erysipelas |
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| caused by S. pyogenes. it is a GAS infection of the dermal layer of skin. usually appears first on the face, often preceded by GAS sore throat. can enter the blood stream causing sepsis. |
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| diseases of streptococci |
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| meningitis, pneumonia, sore throat, otitis media endocarditis, puerperal fever and dental caries |
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| necrotizing fasciitis |
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| caused by strains of GAS. can start with a simple break to the skin, but once it is established it can destroy tissues rapidly requiring surgical debridement and amputation. mortality 40%. endotoxin A is the key to the disease. |
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| super-antigen |
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| immune system dysfunction resulting in tissue damabe. often associated with streptococcal toxic shock syndrome |
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| pseudomonas bacteria characteristics |
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| gram negative rods. aerobes found primarily in soil and water that are resistant to many disinfectants and antibiotics. |
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| P. aeruginosa |
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| model opportunistic pathogen; swimmers ear (an infection of the externl ear canal. |
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| P. dermatitis |
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| self limiting rash acquired from swimming pools, hot tubs. It is a serious problem in burn patients. |
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| pyocanin |
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| contributes to burn infection along with multiple toxins |
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| most commo skin infection |
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| acne. 17 million people in the US, 85% of teens. |
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| comedonal acne |
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| shedding skin cells mixed with sebum clogs follicles. not an infection |
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| propionibacterium acnes |
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| metabolizes sebum trapped in hair follicles. satisfies the gylerol nutritional requirement. causes inflammatory acne: bacterial infection |
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| nodular (cystic) acne |
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| nodules or cysts, inflmed lesions filled with pus deep within tissue; can lead to scarring |
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| papilloma viruses |
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| cause skin cells to proliferate and produce a genign growth called a wart or papilloma. oer 50 types |
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| orthopox virus |
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| smallpox virus |
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| variola virus |
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| two types of skin infctions: variola major (mortality 20%) and variola minor (mortality ~1%) |
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| small pox |
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| transmitted by the respiratory route and moved to the skin vi the bloodstream. causes high fever, skin rash and eath usually comes from respiratory failure |
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| varicella-zoster virus |
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| transmitted by the respiratory route and is localizzed in skin cells, causeing a vesicular rash that fill with pus, form scab then heal. chicken pox |
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| shingles |
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| herpes zoster, characterized by a vesicular rash along the affected cutaneous sensory nerves.. virions move along the nerves causeing severe pain. |
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| HSV-1 infection |
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| transmitted primarily by oral and respiratory routes. infection occurs in infancy; 90% US pop infected. often sublinical, but in some cases cold sores and fever blisters develop. |
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| HSV-2 |
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| transmitted sexually. herpes encephalitis occurs when is infects the brain but rare and cause be caused by eithe rtype. |
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| rubeola |
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| measles. |
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| rubeola vaccine |
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| at 12 month and beyond, if given under 1 they get the disease |
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| complcations of measles |
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| middle ear infections, pneumonia encephalitis and secondary bacterial infections |
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| rubella |
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| red rash and light fever or be asymptomatic. |
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| congenital rubella syndrome |
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| can affect a fetus when a woman contracts rubella during the first trimester of her pregnancy. damages includes stillbirth, deafness eye cataracts, heart defects and mental retardation |
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| microsporum |
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| hair, skin |
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| trichophyton |
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| hair, skin, nails |
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| epidermophyton |
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| skin, nails |
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| dermatomycoses |
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| ringwor, or tinea caused by microsporum, trichophyton, and epidermophyton |
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| tinea capitas |
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| ringworm of the scalp, common in school children |
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| tinea cruris |
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| jock itch |
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| tinea pedis |
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| athletes foot. |
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| dermatophytes |
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| grow on the keratin layer |
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| diagnosis and treatment of rinworm |
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| diagnosis= microscopic examination of skin scrapings of fungal culture of KOH test. treatment= topical antifungal chemicals |
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| candida albicans |
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| causes infections of mucous membranes and common cause of thrush and baginitis. produce pseudo hyphae. |
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| c. albicans in nature |
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| on skin and mucous membranes of the mouth and GI tract. |
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| sarcoptes scabiei |
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| scabies mite. obligate human parasites. transmitted by intimate contact including sexual. most common in schools, camps, barracks jails and prisons |
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| mites |
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| furrow beneath the skin, lay eggs; elevated serpentine line, about 1 mm in width. inflamatory response ith terrible itching |
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| mite diagnosis and treatment |
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| diagnosis= microscopic examination of scrapings. treated with topical application of permethrin |
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| pediculosis human capitis |
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| head lous. |
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| pediculosis human corpus |
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| body louse |
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| lice |
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| reqruie blood meals of their host this leads to itching inflammation and in some cases secondary infections. |
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| rickettsia prowazekii transmission |
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| spread by body lice. epidemic typhus. |
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| haemophilus influenzae |
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| most common bacterial cause of conjuctivitis |
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| adenovirus |
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| most common viral cause of conjunctivitis |
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| conjunctivitis |
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| highly contagious; pseudomonas causes most destructive infection causing serious eye damage. |
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| opthalmia neonatorum transmission |
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| transmission of neisseria gonnorrhoeae from an infected mother to an infant during birth, most common cause of blindness. |
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| inclusion conjuctivitis |
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| infection of the conjuncitva caused by chlamydia trachomatis. is transmitted to infants dring birth and is transmitted in un-chlorinated swimming water |
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| trachoma transmission |
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| transmitted by hands, fomites and perhaps flies. single greates cause of infectious blindness. |
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| erysipelas |
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| treated with ?-lactam antibiotics, esp. cephalosporin |
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| trachoma bacteria |
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| C. trashomatis, |
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| opthalmia neonatorum treatment |
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| all newborn infants treated with an antibiotic to prevent neisseria and chlamydia infection |
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| rickettsia prowazekii symptoms |
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| imptoms include severe headachek sustained high fever, chills, falling blood pressure, stupor, sensitivity to light and delirium. rash begins on the chest about 5 days after fever and spreads to trunk and extremities. |
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| S. aureus symptoms |
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| induce vomiting and diarrhea |
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| shingles treatment |
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| treated with acyclovir and reduce the severity and shorten the duration of episodes |
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| HSV-1 virus |
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| remains latet in trigeminal nerve ganglia but recurrences are trigger by UV, emotional psets and hormonal changes during mestruation |
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| rubeola symptoms |
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| rash begins on the face and spreads |
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| rubeola transmission |
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| transmitted by the repiratory route. contagious. spread through droplet contact of the nose, mouth or thrat. |
