Skin Infections Flashcards

1
Q

What are the layers of the skin?

A

Epidermis (stratum corneum)
Dermis
Subcutaneous Layer

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2
Q

Stratum corneum

A

25 cells thick, dead cells that have migrated from deeper layers

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3
Q

how often does the entire epidermis replace itself?

A

every 25-45 days

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4
Q

keratin

A

give cells the ability to withstand damage, abrasion, and water

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5
Q

Stratum Basale

A

several layers below the stratum corneum, attached to the dermis, source of cells that make up epidermis

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6
Q

What are the other protective characteristics of the skin?

A

sebaceous glands
antimicrobial peptides
sweat
lysozyme

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7
Q

What are the characteristics of the normal biota of the skin?

A

must be capable of living in dry and slaty conditions

majority of the normal biota are not culturable

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8
Q

What genera are found on the skin according to the Human Microbiome Project (HMP)

A
Streptococcus
Staphylococcus
Propionibacterium 
Corynebacterium 
Malassezia
Pseudomonas
Janthinobacterium
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9
Q

What are the maculopapular rash diseases?

A
characterized by flat to slightly raised colored bumps:
measles
rubella
fifth disease
roseola
scarlet fever
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10
Q

What are other skin diseases that are not maculopapular rash diseases?

A

impetigo
cellulitis
SSSS
Rocky Mountain Spotted Fever

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11
Q

What are the vessicular or pustular rash diseases?

A

Chicken pox, small pox, HSV, warts, mycoses

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12
Q

Fifth disease

A

B19 parvovirus

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13
Q

Roseola

A

human herpes viruses

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14
Q

Impetigo

A

bacterial infection of skin common in children- usually near nose/mouth

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15
Q

Cellulitis

A

infected dermis connective tissue and subcutaneous layer

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16
Q

What is the common name for measles?

A

rubeola

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17
Q

Why was there a massive reduction in measles cases within the twentieth century?

A

Vaccination program

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18
Q

How do the symptoms of the measles start?

A

Fever, runny nose, cough and red weepy eyes

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19
Q

What appears within a few days of contracting measles?

A

fine rash: appears first on forehead then spreads to the rest of the body

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20
Q

When do measles symptoms generally disappear?

A

within a week

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21
Q

What are common and less common secondary infections you can get from measles?

A

common: pneumonia and earaches

Less common: encephalitis and subacute sclerosing panechalitis (SSPE: chronic progressive encephalitis)

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22
Q

What is the causative agent of measles?

A

rubeola virus

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23
Q

What are the characteristics of the rubeola virus?

A

pleomorphic, medium sized enveloped
Single stranded RNA genome
Belongs to paramyxovirus family

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24
Q

What are the virulence factors of the rubeola virus?

A

contains spike proteins, one for viral attachment to host, one for fusion with host membrane

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25
Q

What is the pathogenesis of measles?

A

infection via respiratory route» virus replicated in epithelium of upper respiratory tract» spreads to lymph nodes then spreads to the rest of the body

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26
Q

What is an important diagnostic sign of having measles?

A

infected mucous membranes

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27
Q

What is the epidemiology of measles?

A

humans are only natural host

virus spread by respiratory droplets

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28
Q

How many of the population was infected before routine immunization of measles?

A

over 99% of the population

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29
Q

What is the prevention and treatment of measles?

A

vaccine is usually given in conjunction with mumps, rubella, varicella vaccine
MMRV
no antiviral treatment exists for rubeola infection

30
Q

What is scalded skin syndrome?

A

SSSS staphylococcal scalded skin syndrome

toxin mediated disease, occurs primarily in infants, potentially fatal

31
Q

within 48 hours of the infection how is scalded skin syndrome manifested?

A

sin becomes red and wrinkled
large fluid-filled baskets appear
skin is tender to the touch and may feel like sandpaper

32
Q

What are other symptoms of scalded skin syndrome that may arise?

A

malaise, irritability, fever

nose, mouth and genitalia may be painful before other indicators become apparent

33
Q

What is the causative agent of scalded skin syndrome?

A

bacterial agent: staphylococcus aureus

disease is due to the toxins S. aureus produces called exfoliantins

34
Q

What are the characteristics of exfoliatins? What do exfoliatins destroy in scalded skin syndrome?

A

they are toxins coded wither by plasmid or on the bacterial chromosome: destroy integral layers of the outer epidermis

35
Q

How is the toxin carried in scalded skin syndrome? Where does the split occur?

A

released at the site of infection, absorbed and carries by the bloodstream to larger areas of skin, toxin then causes split in epidermis which occurs just below the dead keratinized outer layer of the epidermis

36
Q

What is lost due to the release of the toxin in scalded skin syndrome? and what does this cause?

A

outer layer of skin is lost; causes body fluid loss and increases susceptibility to secondary infection

37
Q

What can the mortality rates reach in scalded skin syndrome?

A

40%

38
Q

how many % of S. aureus strains produce exfoliants?

A

5

39
Q

Which age group can scalded skin syndrome appear in?

A

any age group. most frequently seen in infants, the elderly and immunocompromised

40
Q

What is the only preventative measure for scalded skin syndrome?

A

patient isolation; limits patient exposure to potential secondary pathogens

41
Q

What does the treatment include for scalded skin syndrome?

A

bactericidal antibiotics, antistaphylococcal such as penicillinase- resistant penicillin, treatment also involved removal of dead skin to prevent secondary infection

42
Q

What is another name for the chicken pox?

A

varicella

43
Q

What does it mean that the chickenpox produces a a latent infection?

A

that becomes reactive after recovery of initial illness» shingles

44
Q

Which age groups are symptoms more severe in with chicken pox?

A

older children and adults: 20% of adults develop pneumonia

45
Q

Where does the skin rash appear in chicken pox? what is the rash?

A

back of head, face and mouth, the rash is diagnostic

46
Q

How does the rash progress in varicella?

A

progresses from red spots called macules to small bumps called papules to small blisters called vesicles to puss filled blisters called pustules:
Macules»Papules»Vesicles»Pustules

47
Q

When does the healing begin in varicella?

A

after pustules break and crust over

48
Q

What may lead to congenital varicella syndrome? and what is it?

A

the varicella infection in a newborn. it is the malformation of hands/feet, eyes, skin, neurological damage

49
Q

Which patients are more at risk for varicella?

A

immunocompromised

50
Q

What is a sequella?

A

condition as a result of previous infection

51
Q

What are the sequellas of chicken pox?

A

Shingles or Herpes Zoster

Reye’s Syndrome

52
Q

Shingles

A

caused by reactivation of dormant virus

characterized by rash around waist

53
Q

Reye’s syndrome

A

condition evident by vomiting and coma
predominantly seen in children 5-15
mortality around 30%
asprin therapy increases risk

54
Q

What is the causative agent of chicken pox?

What are its characteristics?

A

varicella-zoster virus
member of the herpesvirus
medium sized enveloped virus
double-stranded DNA genome

55
Q

How does the chicken pox virus enter?

A

respiratory route, replicated and moves to the skin via bloodstream

56
Q

What happens to cells infected by the varicella virus?

A

they swell up and lyse: release virus to enter sensory nerves

57
Q

What does the occurrence of shingles correlate to?

A

with decline in cell mediated type 1 immunity

58
Q

Recrudescence

A

latent virus nerve cell replicated and is carried to the skin

59
Q

When does the incidence of chicken pox increase?

A

in winter and spring

60
Q

how long is the viral incubation period of chicken pox

A

approximately 2 weeks, infective 1-2 days before rash until blisters crust over.

61
Q

What in the body allows survival of isolated viral populations?

A

persistence

62
Q

What is the prevention for chicken pox?

A

attenuated vaccine licensed in 1995
immunization should be done before 13th birthday
should not be given during pregnancy or 3 months prior to pregnancy
can be partially protected by passive immunity via infection of zoster immune globulin (ZIG)

63
Q

What are warts caused by?

A

papillomavirus

64
Q

How can warts infect skin and how long is the incubation period?

A

can infect skin through minor abrasion, incubation period ranges between 2-18 months

65
Q

What are warts called (small tumors)

A

papillomas

66
Q

how many skin warts nearly disappear within 2 years without treatment?

A

1/2

67
Q

What are the characteristics of the papillomavirus? Where can they survive?

A

belong to papovirus family
small nonenveloped
double stranded DNA genome
50 different papillomaviruses known to infect humans
Can survive on inanimate objects including; wrestling mats, towels, shower floors

68
Q

What are skin diseases caused by fungi called?

A

superficial cutaneous mycoses

69
Q

What are superficial cutaneous mycoses caused by?

A

numerous species of molds, invade nails, hair and keratinized layer of skin

70
Q

What are examples of Superficial Cutaneous Mycoses?

A

Tinea capitis= mycosis of scalp
Tinea axillaris= mycoses of the underarm
Tinea cruris= mycoses of the groin; jock itch
Tinea pedis= mycoses of the foot; athletes foot