micro unit 12A - diseases of the skin, eyes, and respiratory system

I: mirobiall diseases of the skin (bacterial + viral infections)

why is skin our best defense?

it acts as a barrier

how does perspiration protect us?

moisture + nutrients for growth of certain microbes; lysozyme + salt inhibits certain bacteria

sebum

nutritive for many microbes, also inhibitory

what microbes make up or skin flora?

s. epidermidis, streptococcus, micrococcus, gram + diphtheroids

the microbes on our skin are resistant to what?

drying and salt

how is our normal flora grouped on our body?

in clumps

does washing our skin eliminate microbes?

no, it only reduces the number of microbes → they will still remain in hair, sweat glands, and repopulate; moist areas have higher populations that metabolize sweat and produce body odor

what are the microbes that cause bacterial skin diseases?

staphylococcus aureus, streptococcus pyogenes, pseudomonas sp., propianibacterium acnes

staphylococcus aureus causes what bacterial skin diseases?

folliculitis

scalded skin syndrome

impetigo of the newborn

toxic shock syndrome

folliculitis

infection of the hair follicle

sty

folliculitis of the eyelash

furuncle

boil, abscess; localized region of pus surrounded by inflamed tissue

carbuncle

body fails to ward off a furuncle; symptoms of generalized infection → focal infection

furuncle → _______

carbuncle

what is staphylococcus aureus called in newborns?

impetigo of the newborn

impetigo of the newborn

thin-walled vesicles on the newborn → hexachlorophene lotion used to treat

scalded skin syndrome

exfoliative toxin that causes the skin to peel off in sheets, occurs in children under 2 years old → seriously ill + requires vigorous antibiotic therapy

toxic shock syndrome

toxin production that causes fever, vomiting, rash, and kidney failure

toxic shock syndrome is caused by what?

absorbent items like tampons, pads, or diapers

what is the mortality rate of toxic shock syndrome?

3-10%

how does staphylococcus look under the microscope?

gram + cocci, clusters, halophile

what does streptococcus pyogenes look like under the microscope?

gram + cocci, chains, not a halophile

streptococcus pyogenes is _____ hemolytic

beta

what is meant by streptococcus pyogenes is “beta hemolytic?”

when inoculated on a blood agar plate, the organism will produce enzymes that will break down rbcs such that they are completely lysed

what population is most susceptible to impetigo/pyoderma?

toddler/grade-school children

how does streptococcus pyogenes get into the skin?

bacteria penetrates the skin through minor abrasion; not usually a serious disease

how is impetigo/pyoderma spread?

contact

what is the treatment for impetigo/pyoderma?

penicillin

if the patient is allergic, then erythromycin

what is the difference of impetigo caused by staphylococcus versus streptococcus

staphylococcus causes impetigo in newborns

streptococcus causes impetigo in toddlers

what bacterial skin diseases are caused by streptococcus pyogenes?

impetigo/pyoderma

erysipelas (st anthony’s fire)

erysipelas

dermal layer of skin infected

what are the symptoms of erysipelas?

red patches with raised margins, high fever + possible sepsis

erysipelas is preceded by what?

strep throat

what is the treatment for erysipelas?

cephalosporin

why is erysipelas known as st anthony’s fire?

red patches all over the body

streptococcus pyogenes is also known as

group a streptococcus

group a streptococcus produces exotoxins that do what?

eat away at the flesh → leads to cellulitis, myositis, necrotizing fasciitis

cellulitis

inflammation of solid tissue

myositis

inflammation of muscle

necrotizing fasciitis

inflammation of the soft connective tissue + necrosis of the soft connective tissue

what is the mortality rate of streptococcus pyogenes/group a streptococcus?

40%+

pseudomonas sp. causes what bacterial skin infections?

dermatitis

burns (when the microbe enters 2nd + 3rd degree), wound infections, bed sores

dermatits

mild rash lasting 2 weeks; usually associated with swimming pools

pseudomonas is opportunistic + nosocomial, how?

enters burns, infected wounds, and bed sores → usually enters in hospitals

what microbe causes the skin to leak blue-green pus with a distinct odor?

pseudomonas sp.

what microbe blocks hair follicles with cells and sebum

propianibacterium acnes; when this blockage is left untreated, whiteheads + blackheads occur

what microbe is responsible for the most common skin infection in the u.s.?

propianibacterium acnes

how does propianibacterium acnes cause acne?

the bacteria metabolizes sebum to free fatty acids → these acids cause inflammation

acne leads to tissue damage which leads to what?

scarring

what is the treatment for acne?

tetracycline, benzoyl peroxide, accutane

what does benzoyl peroxide do?

loosens plugged follicles, effective against propianibacterium acnes

what does accutane do?

inhibits sebum formation

what are the side effects of accutane?

birth defects, excessive skin dryness

warts/papilloma virus

nongenital + benign skin growths

how is HPV transmitted?

contact

what is the incubation for HPV?

several weeks

how is HPV treated?

cryotherapy

acid chemicals

laser surgery

smallpox is caused by what virus?

variola

variola causes what viral skin disease?

smallpox

smallpox

skin scarring

how is smallpox transmitted?

respiratory tract

what is the path of variola?

respiratory tract → internal organs → blood → skin

what virus was the first to gain a vaccine

variola

what year did vaccination of smallpox end?

1970

when is variola most dangerous?

in the blood + organs

varicella causes what viral skin infection?

chickenpox

chickenpox

usually a mild childhood disease; acquired immunity (antibodies made)

how is chickenpox transmitted?

respiratory tract + lesion discharges

why is chicken pox a latent virus?

it hides in the nerve ganglia and returns as shingles

how long before the rash is someone infected with varicella?

one month

how long does it take for chickenpox to heal?

one week

what are the complications of the varicella virus?

encephalitis (inflammation of the brain)

reyes syndrome (brain dysfunction)

pneumonia

is there a vaccine available for chickenpox?

yes

what virus is shingles caused by?

zoster virus

what viral skin disease is caused by the zoster virus?

shingles

what are the symptoms of shingles?

painful vesicles (waist, face, upper chest, back) that follow affected unilateral cutaneous sensory nerves

what is meant by shingles is “latent and opportunistic?”

hides out in the nerve ganglia + takes advantage of the hosts’ weaknesses

what population should be vaccinated for shingles?

50+

herpes simplex 1 is caused by what virus?

hsv 1

what are the symptoms of herpes simplex 1?

cold sores + fever blisters around the mouth

how is herpes simplex 1 transmitted?

oral + respiratory tract

what % of the population is infected with herpes simplex 1?

90% → ONLY 15% will express it

after HSV-1 fever blisters subside, is the patient still contagious?

yes; the virus is still shedding on the skin

is herpes simplex 1 latent? what triggers it?

yes; exposure to sunlight, emotional upset, hormonal changes, stress, infections

what virus causes measles?

rubeola

what viruses cause viral skin diseases?

HPV (human papilloma virus)

variola

varicella

zoster

hsv 1

rubeola

german measles

what are the viral skin diseases?

warts/papilloma virus

smallpox

chickenpox

shingles

herpes simplex 1

measles

rubella

why did the cases of measles increase in 2015?

it is highly communicable especially in those that have not been vaccinated

how is measles transmitted?

respiratory tract

what are the symptoms of measles?

rash, sore throat, fever, koplik’s spots, swollen lymph nodes, light sensitivity

what vaccine is used to prevent measles?

MMR (2 doses)

what are some complications that arise as a result of measles?

pneumonia, encephalitis, ear infections

what virus causes rubella?

german measles

how is rubella different from measles?

it is milder; the rash often goes undetected and it is accompanied by a low-grade fever

what are the symptoms of rubella?

undetected rash, low-grade fever

how is rubella transmitted?

respiratory tract

what vaccine prevents rubella?

MMR

if a pregnant female has never been exposed to rubella and becomes exposed during her first trimester, what is the % that the baby will have congential rubella syndrome (CRS)

33%