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What are the three classes of Microbiota found on the skin?
- Diptheroids
- Staphyococci
- Yeasts
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What are the characteristics of Diptheroids?
- Gram Positve
- Varied in Shape
- Low Virulence
- Body odor caused by bacterial breakdown of sweat
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What are the characteristics of Staphylococci?
- Gram positive
- Salt tolerant
- Principle species on skin is Staphylococcus epidermidis
- Prevents colonization of pathogenic flora
- Maintains balance among microbial skin flora
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What are the characteristics of yeast (fungi)?
- Tiny
- Round or oval, but can be short rods
- Causes rash, dandruff
- Women have more yeast than men
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Symptoms - Small red bump or pimple stemming from hair follicle
Causative
Agent - Stapylococcus Aureus
Pathogenesis - Inflammation caused by
accumulation of leukocytes, becomes a plug of cells and dead tissue, can
spread to the heart, bones, brain
Epidemiology - Found primarily in
nostrils, transmission usually on the hands, shed large numbers of
bacteria
Prevention - Difficult
Treatment - Furuncles and
carbuncles need to be surgically drained, treatment complicated by
antibiotic resistance
Folliculitis
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What is a furuncle?
- Sore stemming from folliculitis
- Extended redness, tenderness swelling
- Numerous furuncles lesions produce a carbuncle
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What is a carbuncle?
Large areas of redness or swelling, stemming from furuncles caused by folliclulitis
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Symptoms - skin appears to be scalded, malaise, irritability, fever
Causative
Agent - Staphylococcus aureus, RNA coded
Pathogenesis - Caused by
exfoliatins produced by S. aureus, split in epidermis, outer layer of
skin lost, mortality rate 40%
Epidemiology - Usually isolated, small
outbreaks in nurseries
Prevention - Patient isolation
Treatment -
Bacteriocidal antibiotics, removal of dead skin to prevent secondary
infections
Scalded Skin Syndrome
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Symptoms - Blisters, followed by yellow crusting, little fever or pain,
lymph nodes enlarge near area
Causative Agent - Streptococcus
pyogenes, gram positive, beta hemolitic
Pathogenesis - through
scratches and minor injuries, bacterial surface components interfere
with phagocytosis
Epidemiology - 2 to 6 year olds living in tropical
regions, usually spread person to person but also through insects and
fomites
Prevention - Cleanliness and avoidance of people with
Impetigo
Treatment - Penicillin and Erythromycin
Streptococcal Impetigo
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Symptoms - Initially light pink spots on palms, wrists, ankles and soles
of feet. Becomes raised bumps all over body. Shock or death can occur.
Causative
Agent - Rickettsia rickettsii, obligate intracellular bacteria, gram
negative, non-motile, coccobaccilus
Pathogenesis - ticks infected
with R. rickettsii
Epidemiology - Zoonotic, US, Canada, Mexico, wood
tick and dog tick
Prevention - No vaccine, avoid tick infested areas,
use DEET
Treatment - Doxycyline and Chloramphenicol high effective
Rocky Mountain Spotted Fever
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Symptoms - First stage, skin rash, chills, fever, headache, stiff neck,
joint and muscle pain. Second stage, 2 - 8 weeks post rash, effects
heart and nervous system. Third stage, arthritis, chronic nervous
system may occur
Causative Agent - Borrelia burgdorferi, large
microaerophillic spirochete, linear genome, not circular
Pathogenesis
- Bite of infected tick, host immunity supressed, enter bloodstream and
spread to other parts of the body
Epidemiology - Zoonotic, wide
spread in US, black-legged in nymph stage main carrier
Prevention -
Avoid ticks, no vaccine
Treatment - Antibiotics effective early, less
effective in late stages
Lyme Disease
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Symptoms - skin rash on back of head, face and mouth. Red spots called
macules, small bumps called papuales, small blisters called vesicles,
pus filled blisters called pustules. Can later become Shingles, herpes
zoster, or reyes syndrome
Causative Agent - Varicella-Zoster virus,
medium sized, enveloped, double stranded DNA
Pathogenesis - Enters
through respiratory route, moves to skin via blood stream, cell mediated
immunity T or B cells
Epidemiology - Incidences have decreased,
incubation period 1 to 2 days
Prevention - attenuated vaccine, 12
months and older
Treatment - Treat symptoms, benadryl, calamine
lotion
Chickenpox
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Symptoms - Begins with fever, funny nose, cough, red weepy eyes, rash
appears within first few days, disappear within 1 week. Pneumonia and
earache are common secondary infections
Causative Agent - Rubeola
virus, pleomorphic, medium sized, enveloped, single strand RNA
Pathogenesis
- Respiratory route, spreads and replicates in lymph nodes, spreads to
all parts of body. Has infected mucous, membranes have "Koplik spots",
white spots can be seen in the back of throat.
Epidemiology - Humans
only natural host, spraed by respiratory droplets. Before vaccine, 99%
infection rate.
Prevention - MMR vaccination
Treatment - no
antiviral treatment
Measles
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Symptoms - slight fever with mild cold symptoms, enlarged lymph nodes
behind ears and back of neck, faint facial rash, joint pain in adults
Causative
Agent - Rubella Virus, member of togavirus family, small enveloped,
single stranded RNA
Pathogenesis - Respiratory route, causes
sustained viremia
Epidemilogy - Humans only natural host, 40% of
infected people fail to develop symptoms
Prevention - attenuated
vaccine, 12 months, boostered at 4 to 6 years
Treatment -
German Measles (3 Day Measles)
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Common in children 6 months to 3 years
Begins abruptly with high
fever, after fever subsides, develops rash on chest and abdomen,
vanishes in a few hours to days
Children do not appear ill.
Caused
by herpes type 6 virus
No vaccine
Treat symptoms
Roseola
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Caused by Papillomavirus
Can infect skin through minor abrasion
Small,
nonenveloped, double stranded DNA
Virus can survive on a number of
inanimate objects
Infects deeper cells of epidermis
Incubation 2 -
18 months
Warts
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