DD 03-10-14 09-10am Skin Infections and Infestations slides notes Flashcards Preview

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Flashcards in DD 03-10-14 09-10am Skin Infections and Infestations slides notes Deck (75):
1

Human Papilloma Virus - Prevalences

Prevalence – up to 10% of children
Genital HPV infection in 20+ million in US

2

Human Papilloma Virus – Ways to Acquire

Breaks in skin/mucosa
Person-to-person contact
Fomites

3

Skin Defense mechanisms

Physical barrier
Desquamation (40,000 min)
Localized immune response (cellular & immunoglobulins)
Anti-microbial peptides (alpha-definsins)
Skin pH

4

HPV Virology – Family, Types, Structure

- Family Papoviridae (papovavirus)
- Many many types (over 200 at least; likely to be reinfected w/another type)
- Non-enveloped double-stranded DNA virus

5

Warts – how they develop & types

= overgrowth of normal skin cell (virus tells cell to proliferate)
- Verruca vulgaris
- Verruca plantaris (on plantar surface of foot)
- Verruca plana (flat warts) – often on mens’ face & women’s legs (spread by shaving)

6

Diagnosis of HPV infection

Clinical + Biopsy + In-situ hybridization

7

Treatment of warts

Can’t target virus, so blow up its house
- Cryotherapy (freeze), Curettage (scrape), Laser (CO2, PDL)
- Salicylic acid, Podophyllin, Cantharidin
- Occlusion (duct tape)
- Imiquimod (Aldaral ), 5% 5-flurouracil, Intralesion candida --> to wake up immune system in the area
- Time (spontaneous involution in many, but continued appearance of new warts)
* Do not need to treat, unless immunosuppressed

8

Herpes Simplex virus infection – Epidemiology

HSV-1 in >90% by age 2

HSV-2 seroprevalence increased with increasing sexual partners

9

Herpes Simplex virus infection – How to Acquire

Through breaks in skin/mucosa

Saliva, vaginal secretion, vesicular fluid, direct skin contact

10

Herpes Simplex Virology – Family, Location of different types, structure

Herpesvirus group

HSV-1 = lips
HSV-2 genitalia

Enveloped double-stranded DNA virus

11

Persistances of HSV

HSV persists in autonomic or sensory ganglia – no cure once infected

Primary & Recurrent Herpes Labialis (cold sore)

12

Herpes – manifestations

Group of blisters on red base, especially recurrent = Herpes until proven otherwise

- Herpetic whitlow –on fingertips
- Herpes progenitalis – on genitals

13

Herpes simplex infection & HIV

Serious infection quickly, may present atypically

14

Diagnosis of HSV infection

Clinical presentation – grouped blisters on red base + story (recurrences, triggers)

Tzanck preparation – scraping & staining on slides (confirms HSV or VZV, but not between them)

Biopsy (cytopathic changes, immunoperoxidase)

Viral culture

HSV type-specific DNA probes/Abs

Serologic evaluation

15

Treatment of HSV infection

Acyclovir – for all types of herpes (five times a day)

Famciclovir, Valacyclovir – longer half-life (once or twice a day; also for suppressive therapy)

Foscarnet (acyclovir-resistance HSV)

16

Varicella-Zoster Infection – Epidemiology

>90% of adults has VZV antibodies

>90% in susceptible household contacts

17

Varicella-Zoster– How to acquire

Primarily spread by respiratory route
Very communicable

18

Chickenpox

= primary VZV infection

Incubation: ~14 days

Initially: Fever, don’t feel good

Lesion: single thin-walled vesicles on erythematous base (dewdrop on rose petal) (not grouped – one dewdrop on one rose petal)

New crops for 3-5 days (lesions in multiple stages of development)

19

Herpes Zosters

= reactivation of dorsal root ganglion varicella zoster virus

*Called Herpes zoster, but NOT herpes infection

Long-lasting post-herpatic neuralgia (often reason for presentation)

Not scarring (unless excoriated)

20

Diagnosis of VZV infection

Clinical presentation
Tzank preparation
Biopsy, Viral culture, Serology
Direct immunofluorescence, PCR

21

Impetigo – epidemiology & how to acquire

Most common superficial bacterial infection of kids

Person-to-person contact

Less commonly through fomite

Predisposing factors: high humidity, cutaneous carriage, poor hygiene

22

Bacteria involved in Impetigo

Strep pyogenes
Staph aureus

23

Streptococcal Non-Bullous Impetigo (Impetigo Contagiosa)

Most commonly affects face & in children

Typically begins as single lesions & becomes multiple

Primary lesions: honey-colored yellow crust

Occasionally mild lymphadenopathy & mild fever, but usually feel fine

Up to 5% are associated w/acute post-strep glomerulonephritis

24

Staphylococcal Non-Bullous Impetigo

Most commonly affects face

Any age group but more commonly in adults

Often a secondary lesion of superficial injury or dermatitis

Primary lesion: Yellow to amber-colored crust w/variable erythema

Often inoculate from your own nose (where staph is carried)

25

Diagnosis of Impetigo

Clinical presentation
Gram stain, Biopsy of blister, Culture w/Antibiotic sensitivity test

26

Cellultis – epidemiology

Increase sensitivity in:
- very young or old
- immunocompromised (though occur in healthy ppl)
- IV drug users
- pts w/ chronic ulcers

Poste-surgical complication

Increased incidence in summer

27

Cellulitis – how to acquire

Infections occur through skin breaks

28

Bacteriology of Cellulitis - Eryiseplas

= facial variant of cellulitis
<-- Group A Beta-hemolytic streptococci

29

Bacteriology of Cellulitis – Cellulitis

Non-face variant of cellulitis
Group A Beta-hemolytic streptococci
Staph aureus
Haemophilus influenza (children)
Less commonly: other streptococci, Pneumococcus, Klebsiella, Yersinia, mixed flora

30

Erysipelas – location, incubation, appearance

Confined to face

Incubates 2-5 days

Bilateral facial involvement

Painful, bright red, indurated, sharp border (“cliff drop border”)

+/- Lymphadenopathy

31

Staphylococcal cellulitis

Primary lesion – tender, ill-defined area of painful erythema w/variable induration

Lymphatic streaking is common

Lymphadenopathy is variable

32

Cellulitis Diagnosis

Clinical presentation

CBC (leukocytosis variably)

Biopsy consistant w/ organisms is HARD to find

Culture + gram stain more sensitive & specific (occasionally used)

Blood culture = + in 10%

33

Sexually transmitted disease – Risk from single sexual contact & incidence

~30%

Incidence peaked in 90s, but now going up again since 2006

34

Syphilis – cause

Terponema pallidum
= Spirochete w/6-14 spirals
= 7-15 microns long, 0.25 micron width
= can’t cultured; must ID in other ways

35

Syphilis – Clinical Classifications

Primary
Secondary (early latent – 1-2 years; late latent)
Tertiary
Congenital

36

Primary syphilis - time & lesion type

Incubation 10-90 days (inversely proportional to inoculum’s size)

In regional lymph nodes in 30 min

Painless chancres full of spirochetes, highly communicable

37

Chancre in primary syphilis

Non-tender, Indurated

Genital or extragenital

May be unnoticeable if in hidden location

Heals in 3-6 weeks

Lymphadenopathy

38

Secondary syphilis – time

Begins 4-10 weeks after onset of chancre

Original chancre may be present

Lymphadenopathy in 90%

Several types of secondary skin lesions

Typically lasts 2-12 weeks

*typically pts present w//secondary syphilis

39

Secondary syphilis – types of skin lesions

- Non-pruritic papulosquamous lesions
- Condylomata lata
- Nonscarring “moth eaten” alopecia
- Split papules at oral commissures
- Annular lesions on face
- Oral lesions
- Lesions on palms & soles (rarely involved except in syphilis)

*If you look at a rash & don’t know what it is, always safe to put syphilis, sarcoid, & drug rxn in

40

Diagnosis of syphilis

Clinical presentation – rash + lymphadenopathy, palms & soles, etc.

Darkfield microscopy

Biopsy

Serology
- Nontreponemal (VDRL, *RPR*) tests
- Treponemal (FTA-ABS, MHA-TP) tests

41

Dermatophytes

Fungi that eat keratin (skin, hair, nails)--> can’t get deep infection, rarely get septic

Ex: epidermophyton (sock & jocks, no hair), trichophyton, microsporum

42

Fungal skin infections – how to acquire

Human or Animal (farm, cats) contact
Water, soil
Fomites, Clothing

43

Tinea capitis

Hair infection (esp. w/short dark curly hair)

Gray patch tinea = perfectly round, associated hair loss, occipital lymphadenopathy

Black dot tinea capitis

Kerion tinea capitis – so much fungi that there is a pus pocket; scaling on scalp is rarely bacterial – don’t use antibiotics, use antifungals

44

Tinea faciei

affects face
annular placques w/some central clearing

45

Tinea barbae

- on face
- from men, barbershops, animals

46

Tinea corporis

on body

47

Tinea cruris

groin (often spares scrotum, penis)

48

Tinea pedis

- on feet
- annular placques moving outward from central ring;
- can be hyperkeratotic

49

Tinea manum

- on hands
- usually only affects 1 hand (--> 2-feet-1-hand syndrome)

50

Majocchi’s granuloma

- Tinea corporus w/ involvement of hair follciles
- Deeper granulomatous infection (must use systemic antifungals now)

51

Onychomycosis w/Tinea pedis/manus

Subungual (under nail) infection, lifting of nail

52

Diagnosis of tinea fungal infections

KOH test on leading edge
Dermatophyte test medium
Biopsy of leading edge

53

Treatment of tinea pedis

Topical naftifine
OTC topical antifungals: Tinactin>Lotrimin

54

Candidiasis – epidemiology & location

Increased prevalence in
- diabetes mellitus
- occlusion
- corticosteroid use
- broad-spectrum antibiotics

Affects mucous membranes & skin

Normal flora

55

Mycology – food source, most common species

Preferred food source = glucose or serum

Most common pathogenic species
- Candida albicans
- C. trpicalis, C kefyr, C. glabrata, C. parapsilosis

56

Types of candidal infections

- Thrush in HIV infections
- Candidasis – Perleche (edges of mouth, chronically moist area)
- Erosio Interdigitalis Blastomycetic Chronica (finger webs
-Candida Diaper Dermatitis

57

Candidiasis – Dx

Clinical presentation
KOH, Gram stain, Culture (Sabouraud’s agar, Nickerson’ medium), Biopsy

58

Tinea versicolor – epidemiology

Worldwide distribution, more common in humid/warm climates

Confined to post-pubertal pts

59

Tinea versicolor – mycology

Malassexia furfur (Pityrosporum obiculare)

Food source: follicular lipids

60

Tinea versicolor – Clinical features

Distribution: mostly trunk
Primary lesion: asymptomatic, tan-colored, subtly scaly macule or patch

Clinical variants: hypopigmented or folliculitis

61

Diagnosis of Tinea versicolor

Clinical presentation
KOH (spaghetti & meatballs), Methylene blue, Biopsy, Culture = rarely done

62

Scabies – epidemiology

Worldwide distribution, all ages, races, socioeconomic groups

Highest prevalence in children & sexually active adults

63

Scabies – how to acquire

Spread of mites via person-to-person contact

64

Scabies etiology

Sarcoptes scaciei var. hominis (also an animal variant, but doesn’t transmit)

Mites (.35 by .3 mm) – possible to see w/ naked eye (but usually need light microscopy)

Variable number of mites per host (usually <100)

65

Scabies - distribution

Symmetric soft skin distribution
- Interdigital web space
- Flexural wrist
- Waist
- Axillae
- Genitalia
- Breast

66

Scabies - symptoms

Pruritus (nocturnal accentuation)

Primary Lesions – erythematous papules & burrows, nodular genitalia lesions

Secondary Lesions - Excoriation, Infection

67

Norwegian scabies

In infants or neurologically-compromised pts (no itch response)

In immunologically-compromised pts w/decreased sensory function

---> hundreds & hundreds of mites

68

Diagnosis of scabies

Clinical presentation (burrows, genital nodules)

Mineral oil preps (mites, eggs, mite feces – scybala)

Skin biopsy (host response, burrows, mites, eggs, scybala)

69

Lice infestation – epidemiology

Worldwide

Body lice: most common in indigent (homeless, etc.)

Head lice: 12 million new case/ year; usually in children

Crab lice: most common in homosexuals & young men

70

Lice infestation – etiology

Pediculus human
--- Scalp louse –var. cap
--- Body louse – var. corporis

Pubic louse = Phthirus pubis

71

Scalp lice

Lices – closer to scalp
Nids (egg casings) – not as close to scalp, on hair

72

Body lice – morphology, location, clinical findings

Lice & eggs = morphologically identical to scalp lice

Location – only on clothing (eat then leave skin)

Truncal erythematous papules & macules

Intense pruritus

Secondary excoriation

73

Pubic lice – distribution, symptoms, nid/lice appearance

Primarily genital (less commonly eyelashes, beard, axilla)

Marked pruritus of genital area

Nits similar to head/body lice

Adult: six legs, crab-like, easily found attached to base of hair follicles

74

Lice infestation –Dx

Clinical presentation
Demonstration of louse or nit

75

Treatment of scalp lice

Key to treatment = get rid of nids (eggs) w/comb
Less important is killing the lice w/shampoo etc.

Elimite cream (permethrin 5%)
RID shampoo & comb