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microbiology > chapter 21: diseases of the skin and eye > Flashcards

chapter 21: diseases of the skin and eye Flashcards

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1
Q

the skin is an _____ _____

A

inhospitable environment

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2
Q

_____ inhibits many microbes

A

salt

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3
Q

_______, present in secretions, hydrolyzes peptidoglycan

A

lysozyme

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4
Q

_____ ____ inhibit some pathogens

A

fatty acids

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5
Q

some pathogens and diseases of the skin are….

A

not necessarily skin diseases, but have such a manifestation on the skin that they must be considered when trying to determine cause of symptoms

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6
Q

successful flora of the skin are resistant to

A

drying, low pH tolerant

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7
Q

staphylococci and micrococci are _____ pathogens of the skin

A

successful, gram positive

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8
Q

gram positive pleomorphic rods ….

A

metabolize the oils found in sebum producing propionic acid thus reducing skin pH to 3-5

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9
Q

propionobacterium acnes

A

an anaerobe that inhabits hair follicles

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10
Q

pleomorphic rods

A

diphtheroids

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11
Q

corynebacterium xerosis

A

an aerobe commonly found inhabiting skin surface

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12
Q

malassezia sp.

A

a yeast grows on oily secretions and thought to be responsible for scaling condition of dandruff

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13
Q

staphylococci are

A

gram + cocci, form clusters, coagulase + (or -)

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14
Q

coagulase

A

enzyme that clots blood, highly associated with disease

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15
Q

coagulase negative species

A

S. epidermidis, not typically pathogenic unless through break in skin or in blood

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16
Q

staphylococci might represent __% of flora

A

90

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17
Q

_____ helps staph avoid phagocytosis, important virulence factor

A

capsule

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18
Q

catalase + or -

A

aka hydrogen peroxidase, += staph, more virulent; - =strep, less virulent (strep just runs through body)

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19
Q

why is coagulase important for staph species?

A

helps wall off infection in body to avoid immune system, if they were mobile could be phagocytized much quicker

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20
Q

staphylococcus aureus

A

coagulase +, commonly found in nasal cavity, produces golden colonies, beta-hemolysis, several toxins and extracellular factors responsible for virulence

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21
Q

pathogenicity island

A

large insert of DNA that encodes for virulence factors unique to S. aureus, not found in S. epidermidis (why it’s not as virulent)

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22
Q

beta-hemolysis

A

complete clearing

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23
Q

alpha-hemolysis

A

greening clearing

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24
Q

gamma-hemolysis

A

no clearing

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25
Q

staphylococcus epidermidis

A

gram + cocci, coagulase -

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26
Q

staphylococcus aureus

A

gram + cocci, coagulase + (most virulent)

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27
Q

folliculitis

A

infection of hair follicles

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28
Q

sty

A

folliculitis of eyelash

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29
Q

furuncle

A

abscess; pus surrounded by inflamed tissue

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30
Q

carbuncle

A

inflammation of tissue under skin; subdermal furuncles, larger patch, more dangerous because underneath keratin layer; can be treated with hot water compress, if not successful can use antibiotics

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31
Q

impetigo

A

crusting (nonbullous-no pimple-like head) sores, spreading by autoinoculation; childhood disease

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32
Q

S. aureus virulence determinants

A

produce several proteins and toxins that:

  • prevent phagocytosis
  • imobilize neutrophils
  • kill phagocytes (neutrophils)
  • form clots (helpful in establishing an abscess)
  • induce vomiting and diarrhea
  • trigger scalded skin syndrome
  • cause toxic shock syndrome (life-threatening, fever, vomiting, organ failure [esp. kidneys], rash)
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33
Q

intoxications caused by certain strains of S. aureus

A

TSS-toxic shock syndrome toxin 1
scalded skin syndrome (exfoliative Toxin-A): also responsible for bullous impetigo (localized version), impetigo of the newborn

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34
Q

scalded skin syndrome is

A

a protease that cleaves a factor responsible for induction of scalded skin syndrome symptoms, not typically very dangerous

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35
Q

streptococci cause many diseases…

A

meningitis, pneumonia, sore throat, otitis media, endocarditis, puerperal fever, and dental caries

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36
Q

streptococci grow and secrete

A

toxins such as hemolysins

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37
Q

hemolysins

A

lyse various types of cell types including RBCs

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38
Q

____-hemolytic strep most frequently associated with disease

A

beta

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39
Q

alpha-hemolytic disease that is still associated with disease

A

streptococcus pneumoniae

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40
Q

streptococci are categorized by

A

serological groups antigens (A-T, based on surface carbohydrate antigenic structure [Lancefield carbohydrate grouping] )

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41
Q

Group A Strep

A

GAS, synonymous with S. pyogenes, most important B-hemolytic strep; can be deadly, divided into 80 antigenic types based on M protein

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42
Q

M protein

A

involved in adherence, complement activation and phagocytic avoidance

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43
Q

why is activating complement beneficial for strep?

A

hijacks system, inflammation helps because helps avoid opsonization and phagocytosis

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44
Q

hyaluronic acid capsule

A

anti-phagocytic; masks bacterium due to resemblance to human CT

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45
Q

streptokinases

A

dissolve blood clots

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46
Q

hyaluronidase

A

degrades CT

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47
Q

DNase

A

degrades DNA

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48
Q

streptolysins

A

lyse RBCs and poison neutrophils

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49
Q

toxic shock syndrome toxin is an

A

important strep toxin that induces toxic shock

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50
Q

erysipelas

A

GAS infection of the dermal layer of skin; usually appears first on face; often preceded by GAS sore throat, can enter blood stream and cause sepsis

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51
Q

erysipelas is treated with

A

B-lactam antibiotics, especially cephalosporin

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52
Q

necrotizing fasciitis

A

“flesh-eating disease”, caused by invasive strains of GAS, can start as simple break in skin, can be dismissed early on; once established, can destroy tissues rapidly requiring surgical debridement and amputation; mortality rate about 40% in systemic cases, exotoxin A production key to disease, often associated with TSS

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53
Q

super-antigen

A

immune system disfunction resulting in tissue damage

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54
Q

strep pyogenes

A

GAS

55
Q

strep pneumoniae

A

group D strep

56
Q

pseudomonas aeruginosa

A

aerobic gram - rod common to soil and water, model opportunistic pathogen

57
Q

pseudomonas skin infections

A

diverse metabolic capabilities: can grow on varied and unusual organic compounds sources; resistant to many antibiotics and disinfectants; serious problem in burn patients (esp 2nd and 3rd degree), multiple toxins and pyocyanin contribute to burn infection pathogenesis, multiple drug resistance exacerbates illness, sepsis can be life threatening, otitis externa (swimmer’s ear, infection of external ear canal)

58
Q

pseudomonas dermatitis

A

self limiting rash acquired from swimming pools, hot tubs

59
Q

acne is the ____ common skin infection

A

most, 17 million people in US, 85% of teens

60
Q

acne is caused by

A

shedding skin cells mix with sebum and clog follicles (comedonal acne)

61
Q

inflammatory acne

A

bacterial infection, usually propionibacterium acnes (an aerobic diphtheroid)

62
Q

P. acnes

A

has nutritional requirement for glycerol found in sebum, results in an inflammatory infection

63
Q

nodular/cystic acne

A

nodules or cysts, inflamed lesions filled with pus deep within tissue, can lead to scarring

64
Q

warts

A

papillomas; benign skin growths caused by viruses, >50 types of papilloma viruses known, treated with cryotherapy, some skin and cervical cancers associated with certain strains of papilloma virus

65
Q

smallpox

A

caused by an orthopox virus known as the smallpox (variola) virus, becomes systemic, high fever, rash, death usually from respiratory failure, lesions result in severe scarring typically on face, head and neck; first disease for which immunity was artificially induced

66
Q

smallpox: variola major

A

mortality rate >20%

67
Q

smallpox: variola minor

A

mortality rate about 1%, appeared circa 1900

68
Q

smallpox transmission

A

via respiratory route

69
Q

edward jenner

A

1796, observed that people who caught cowpox while working with cows were known not to catch smallpox, smallpox now eradicated from human populations

70
Q

chickenpox (varicella)

A

relatively mild childhood disease, acquired by inhalation or deposition in nasopharynx, virus localizes in skin in about 2 weeks, rash develops- vesicles fill with pus, form scab and heal, midsection usually affected

71
Q

varicella-zoster

A

human herpes viruse-3, shingles

72
Q

chickenpox in early pregnancy can result in

A

fetal death in about 2% of cases

73
Q

shingles

A

reemergence of chickenpox, virions move along peripheral nerves to cutaneous sensory nerves of skin inducing severe pain

74
Q

chickenpox: following primary disease…

A

virus enters peripheral nervous system remains latent in tissues for life

75
Q

anti-viral shingles drugs

A

acyclovir, valacyclovir and famicyclovir reduce severity and shorten duration of shingles episodes

76
Q

Human Herpes Virus species divided into 2 subtypes

A

HSV-1 and HSV-2

77
Q

HSV-1

A

primarily transmitted by oral and respiratory routes, infection occurs in infancy; 90% of US population infected, infection often subclinical, but in some cases cold sores and fever blister develop; remains latent in trigeminal nerve ganglia (face and CNS connection) until reactivation, travels down nerve axon to site of eruption

78
Q

recurrences of HSV-1 triggered by

A

UV, emotional upsets, and hormonal changes during menstruation

79
Q

HSV-2

A

very similar to 1, though transmitted primarily by sexual contact

80
Q

Herpes encephalitis

A

rare, can be caused by either 1 or 2, but fatality rater with HSV-2 approached 70% if untreated

81
Q

measles (rubeola) is a member of

A

paramyxoviridae

82
Q

measles

A

extremely contagious viral disease, spread through droplet contact from nose, mouth or throat; rash that typifies disease begins on face and spreads to trunk and extremities, extremely dangerous infection for infants (serious complications)

83
Q

measles vaccine

A

MMR, measles, mumps, rubella, 95% effective; delivered at 12 months and beyond; although responsible for near elimination of disease, use has resulted in children <1 year old becoming infected; middle ear infections, pneumoniae, encephalitis (1/1000)

84
Q

subacute sclerosing panencephalitis

A

rare complication (about 10 cases per 100,000 measles infection; incidence as high as 30/100,000 in some countries); not a manifestation of virus but rather an abnormal post-infection immune reaction; occuring 1-10 years following recovery…severe neurological symptoms, syndrome is always fatal; prevention: immunization to prevent initial measles infection

85
Q

rubella is known as

A

german measles

86
Q

rubella is a

A

much more mild viral illness than rubeola, often goes undetected

87
Q

rubella

A

characteristic rash has small spots not raised above skin

88
Q

congenital rubella syndrome

A

pregnant mother contracting disease in first trimester, 35% chance of severe fetal damage including deafness, eye cataracts, heart defects, mental retardation, death

89
Q

cutaneous mycoses are

A

fungal diseases of the skin, hair, and nails

90
Q

cutaneous mycoses caused by

A

dermatophytes, grow on keratin layer

91
Q

dermatomycoses

A

tinea, ringworm

92
Q

tinea capitas

A

ringworm of scalp; common among school children

93
Q

tinea cruris

A

jock itch

94
Q

tinea pedis

A

athlete’s foot

95
Q

fungi generally responsible for infections

A

trichophyton (hair, skin, nails), microsporum (hair, skin), epidermophyton (skin and nails)

96
Q

diagnosis for cutaneous mycoses requires a

A

KOH microscopic exam

97
Q

treatment for cutaneous mycoses

A

over the counter topicals: miconazol, clotrimazole, (nailsL oral itraconazole)

98
Q

Candida albicans

A

typically a yeast-lilke fungus that produces pseudo hyphae; ubiquitous in nature and present on skin and mucous membranes of the mouth and genitourinary tract; growth is suppressed by normal microbiota

99
Q

use of antimicrobials on candida albicans

A

not effective against Candida, allows outgrowth of fungus

100
Q

pseudohyphal form

A

resistant to phagocytosis, a potential factor in pathogenesis

101
Q

thrush

A

oral candidiasis

102
Q

candidiasis is a common cause of

A

vaginal yeast infection

103
Q

immunosuppressive circumstances such as AIDS, cancer chemotherapy, autoimmune disease treatments…

A

promote candidiasis and exacerbate outcome

104
Q

mites

A

arthropods, subclass Acari; >48,000 described species

105
Q

scabies mite

A

Sarcoptes scabiei

106
Q

mites are obligate human parasites

A

cannot live off of human host for more than 24 hours

107
Q

scabies

A

transmitted by intimate contact including sexual; bed sharing; etc. most common in schools, camps, barracks, jails and prisons because of the constant and unavoidable contact between people

108
Q

how do scabies act/symptoms that come

A

burrow beneath skin, lay eggs; elevated serpentine line, about 1 mm in width, inflammatory response with terrible itching

109
Q

scabies diagnosed by

A

microscopic examination of scrapings

110
Q

treatment of scabies

A

topical application of permethrin

111
Q

pediculosis

A

lice

112
Q

pediculosis humanis capitis

A

head louse

113
Q

pediculosis humanus corpus

A

body louse

114
Q

lice require

A

blood meals of their host, this leads to itching, inflammation, and in some cases secondary infections

115
Q

body lice, but not head lice, also spread…

A

epidmic typhus, a Rickettsia prowazekii

116
Q

symptoms of epidmic typhus

A

severe headache, sustained high fever, cough, rash, severe muscle pain, chills, falling blood pressure, stupor, sensitivity to light, and delirium. A rash begins on the chest about 5 days after the fever appears and spreads to the trunk and extremities. a symptom common to all forms of typhus is a fever which may reach 39 degrees celsius

117
Q

lice carry organism…

A

shed them in their feces, scratching self inoculates

118
Q

conjunctivitis

A

pink eye, inflammation of the conjunctiva, highly contagious

119
Q

haemophilus infulenzae

A

most common bacterial cause of conjunctivitis

120
Q

adenovirus

A

most common viral cause of conjunctivitis

121
Q

pink eye:contact lens use a ____ ___

A

predisposing factor

122
Q

pink eye:pseudomonas

A

causes the most destructive infection causing serious eye damage

123
Q

pink eye preventative

A

use of commercial lens cleaners and maintaining proper care and use

124
Q

ophthalmia neonatorum

A

Neisseria gonorrhoeae transmitted to newborn while passing through the birth canal of mother with gonorrhea; historically one of the most common causes of neonatal blindness; prevented in early 20th century by application of 1% silver nitrate in eyes of all newborns (law), today sliver nitrate replaced by antibiotics

125
Q

Neisseria gonorrhea

A

gram - aerobic diplococcus, obligate human pathogen

126
Q

trachoma

A

single greatest cause of infectious and preventable blindness worldwide (3% of all world’s blindness) 8 million individuals irreversibly impaired; 84 million active cases in need of treatment

127
Q

trachoma cause

A

certain serotypes of Chlamydia trachomatis (not same ones that cause Chlamydial STDs)

128
Q

trachoma is easily spread through

A

direct personal contact, shared towels and cloths, and flies that have come into contact with the eyes or nose of an infected person

129
Q

trachoma is endemic to

A

arid regions of Africa and Asia, nearly all children infected early in life; 500 million active cases worldwide, 7 million blinded individuals. sanitary practice, health education and antibiotics help prevent or treat

130
Q

S.A.F.E.

A

surgery to correct the advanced, blinding stage of the disease (trichiasis), antibiotics to treat active infection (Azithromycin), facial cleanliness, environmental improvements in the areas of water and santitation to reduce disease transmission

131
Q

inclusion conjunctivitis

A

caused by Chlamydia trachomatis (STD strains); transmitted at birth through canal of mother with STD infection

132
Q

symptoms of inclusion conjunctivitis

A

redness of the eyes, swelling of the eyelids, and discharge of pus; likely to appear 5-12 days after birth. about half of newborns with chlamydial conjunctivitis also have the infection in other parts of their bodies. the bacteria can infect the lungs and nasopharynx

133
Q

treatment for inclusion conjunctivitis

A

tetracycline

microbiology (10 decks)

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