chapter 21: diseases of the skin and eye Flashcards
1
Q
the skin is an _____ _____
A
inhospitable environment
2
Q
_____ inhibits many microbes
A
salt
3
Q
_______, present in secretions, hydrolyzes peptidoglycan
A
lysozyme
4
Q
_____ ____ inhibit some pathogens
A
fatty acids
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
6
Q
successful flora of the skin are resistant to
A
drying, low pH tolerant
7
Q
staphylococci and micrococci are _____ pathogens of the skin
A
successful, gram positive
8
Q
gram positive pleomorphic rods ….
A
metabolize the oils found in sebum producing propionic acid thus reducing skin pH to 3-5
9
Q
propionobacterium acnes
A
an anaerobe that inhabits hair follicles
10
Q
pleomorphic rods
A
diphtheroids
11
Q
corynebacterium xerosis
A
an aerobe commonly found inhabiting skin surface
12
Q
malassezia sp.
A
a yeast grows on oily secretions and thought to be responsible for scaling condition of dandruff
13
Q
staphylococci are
A
gram + cocci, form clusters, coagulase + (or -)
14
Q
coagulase
A
enzyme that clots blood, highly associated with disease
15
Q
coagulase negative species
A
S. epidermidis, not typically pathogenic unless through break in skin or in blood
16
Q
staphylococci might represent __% of flora
A
90
17
Q
_____ helps staph avoid phagocytosis, important virulence factor
A
capsule
18
Q
catalase + or -
A
aka hydrogen peroxidase, += staph, more virulent; - =strep, less virulent (strep just runs through body)
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
20
Q
staphylococcus aureus
A
coagulase +, commonly found in nasal cavity, produces golden colonies, beta-hemolysis, several toxins and extracellular factors responsible for virulence
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)
22
Q
beta-hemolysis
A
complete clearing
23
Q
alpha-hemolysis
A
greening clearing
24
Q
gamma-hemolysis
A
no clearing
25
staphylococcus epidermidis
gram + cocci, coagulase -
26
staphylococcus aureus
gram + cocci, coagulase + (most virulent)
27
folliculitis
infection of hair follicles
28
sty
folliculitis of eyelash
29
furuncle
abscess; pus surrounded by inflamed tissue
30
carbuncle
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
31
impetigo
crusting (nonbullous-no pimple-like head) sores, spreading by autoinoculation; childhood disease
32
S. aureus virulence determinants
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)
33
intoxications caused by certain strains of S. aureus
TSS-toxic shock syndrome toxin 1
scalded skin syndrome (exfoliative Toxin-A): also responsible for bullous impetigo (localized version), impetigo of the newborn
34
scalded skin syndrome is
a protease that cleaves a factor responsible for induction of scalded skin syndrome symptoms, not typically very dangerous
35
streptococci cause many diseases...
meningitis, pneumonia, sore throat, otitis media, endocarditis, puerperal fever, and dental caries
36
streptococci grow and secrete
toxins such as hemolysins
37
hemolysins
lyse various types of cell types including RBCs
38
____-hemolytic strep most frequently associated with disease
beta
39
alpha-hemolytic disease that is still associated with disease
streptococcus pneumoniae
40
streptococci are categorized by
serological groups antigens (A-T, based on surface carbohydrate antigenic structure [Lancefield carbohydrate grouping] )
41
Group A Strep
GAS, synonymous with S. pyogenes, most important B-hemolytic strep; can be deadly, divided into 80 antigenic types based on M protein
42
M protein
involved in adherence, complement activation and phagocytic avoidance
43
why is activating complement beneficial for strep?
hijacks system, inflammation helps because helps avoid opsonization and phagocytosis
44
hyaluronic acid capsule
anti-phagocytic; masks bacterium due to resemblance to human CT
45
streptokinases
dissolve blood clots
46
hyaluronidase
degrades CT
47
DNase
degrades DNA
48
streptolysins
lyse RBCs and poison neutrophils
49
toxic shock syndrome toxin is an
important strep toxin that induces toxic shock
50
erysipelas
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
51
erysipelas is treated with
B-lactam antibiotics, especially cephalosporin
52
necrotizing fasciitis
"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
53
super-antigen
immune system disfunction resulting in tissue damage
54
strep pyogenes
GAS
55
strep pneumoniae
group D strep
56
pseudomonas aeruginosa
aerobic gram - rod common to soil and water, model opportunistic pathogen
57
pseudomonas skin infections
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
pseudomonas dermatitis
self limiting rash acquired from swimming pools, hot tubs
59
acne is the ____ common skin infection
most, 17 million people in US, 85% of teens
60
acne is caused by
shedding skin cells mix with sebum and clog follicles (comedonal acne)
61
inflammatory acne
bacterial infection, usually propionibacterium acnes (an aerobic diphtheroid)
62
P. acnes
has nutritional requirement for glycerol found in sebum, results in an inflammatory infection
63
nodular/cystic acne
nodules or cysts, inflamed lesions filled with pus deep within tissue, can lead to scarring
64
warts
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
smallpox
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
smallpox: variola major
mortality rate >20%
67
smallpox: variola minor
mortality rate about 1%, appeared circa 1900
68
smallpox transmission
via respiratory route
69
edward jenner
1796, observed that people who caught cowpox while working with cows were known not to catch smallpox, smallpox now eradicated from human populations
70
chickenpox (varicella)
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
varicella-zoster
human herpes viruse-3, shingles
72
chickenpox in early pregnancy can result in
fetal death in about 2% of cases
73
shingles
reemergence of chickenpox, virions move along peripheral nerves to cutaneous sensory nerves of skin inducing severe pain
74
chickenpox: following primary disease...
virus enters peripheral nervous system remains latent in tissues for life
75
anti-viral shingles drugs
acyclovir, valacyclovir and famicyclovir reduce severity and shorten duration of shingles episodes
76
Human Herpes Virus species divided into 2 subtypes
HSV-1 and HSV-2
77
HSV-1
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
recurrences of HSV-1 triggered by
UV, emotional upsets, and hormonal changes during menstruation
79
HSV-2
very similar to 1, though transmitted primarily by sexual contact
80
Herpes encephalitis
rare, can be caused by either 1 or 2, but fatality rater with HSV-2 approached 70% if untreated
81
measles (rubeola) is a member of
paramyxoviridae
82
measles
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
measles vaccine
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
subacute sclerosing panencephalitis
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
rubella is known as
german measles
86
rubella is a
much more mild viral illness than rubeola, often goes undetected
87
rubella
characteristic rash has small spots not raised above skin
88
congenital rubella syndrome
pregnant mother contracting disease in first trimester, 35% chance of severe fetal damage including deafness, eye cataracts, heart defects, mental retardation, death
89
cutaneous mycoses are
fungal diseases of the skin, hair, and nails
90
cutaneous mycoses caused by
dermatophytes, grow on keratin layer
91
dermatomycoses
tinea, ringworm
92
tinea capitas
ringworm of scalp; common among school children
93
tinea cruris
jock itch
94
tinea pedis
athlete's foot
95
fungi generally responsible for infections
trichophyton (hair, skin, nails), microsporum (hair, skin), epidermophyton (skin and nails)
96
diagnosis for cutaneous mycoses requires a
KOH microscopic exam
97
treatment for cutaneous mycoses
over the counter topicals: miconazol, clotrimazole, (nailsL oral itraconazole)
98
Candida albicans
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
use of antimicrobials on candida albicans
not effective against Candida, allows outgrowth of fungus
100
pseudohyphal form
resistant to phagocytosis, a potential factor in pathogenesis
101
thrush
oral candidiasis
102
candidiasis is a common cause of
vaginal yeast infection
103
immunosuppressive circumstances such as AIDS, cancer chemotherapy, autoimmune disease treatments...
promote candidiasis and exacerbate outcome
104
mites
arthropods, subclass Acari; >48,000 described species
105
scabies mite
Sarcoptes scabiei
106
mites are obligate human parasites
cannot live off of human host for more than 24 hours
107
scabies
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
how do scabies act/symptoms that come
burrow beneath skin, lay eggs; elevated serpentine line, about 1 mm in width, inflammatory response with terrible itching
109
scabies diagnosed by
microscopic examination of scrapings
110
treatment of scabies
topical application of permethrin
111
pediculosis
lice
112
pediculosis humanis capitis
head louse
113
pediculosis humanus corpus
body louse
114
lice require
blood meals of their host, this leads to itching, inflammation, and in some cases secondary infections
115
body lice, but not head lice, also spread...
epidmic typhus, a Rickettsia prowazekii
116
symptoms of epidmic typhus
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
lice carry organism...
shed them in their feces, scratching self inoculates
118
conjunctivitis
pink eye, inflammation of the conjunctiva, highly contagious
119
haemophilus infulenzae
most common bacterial cause of conjunctivitis
120
adenovirus
most common viral cause of conjunctivitis
121
pink eye:contact lens use a ____ ___
predisposing factor
122
pink eye:pseudomonas
causes the most destructive infection causing serious eye damage
123
pink eye preventative
use of commercial lens cleaners and maintaining proper care and use
124
ophthalmia neonatorum
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
Neisseria gonorrhea
gram - aerobic diplococcus, obligate human pathogen
126
trachoma
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
trachoma cause
certain serotypes of Chlamydia trachomatis (not same ones that cause Chlamydial STDs)
128
trachoma is easily spread through
direct personal contact, shared towels and cloths, and flies that have come into contact with the eyes or nose of an infected person
129
trachoma is endemic to
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
S.A.F.E.
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
inclusion conjunctivitis
caused by Chlamydia trachomatis (STD strains); transmitted at birth through canal of mother with STD infection
132
symptoms of inclusion conjunctivitis
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
treatment for inclusion conjunctivitis
tetracycline
