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BRS DERMATOLOGY > 1b// Infections and infestations of the skin > Flashcards

1b// Infections and infestations of the skin Flashcards

1
Q

What are the pathogens that can cause skin infections and infestations?

A

bacteria
virus
parasites
fungus

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2
Q

What pathogen causes folliculitis?

A

bacteria

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3
Q

What is folliculitis?

A

Follicular erythema; sometimes pustular .

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4
Q

Is folliculitis infectious?

A

May be infectious or non-infectious.

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5
Q

What is another word for non-infectious folliculitis? And what is it associated with?

A

Eosinophilic (non-infectious) folliculitis is associated with HIV.

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6
Q

Why may recurrent cases of folliculitis occur?

A

Recurrent cases may arise from nasal carriage of Staphylococcus aureus, particularly strains expressing Panton- Valentine leukocidin (PVL).

there is a reservoir of staphylococcus in nose and throat

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7
Q

What is the treatment of folliculitis?

A

Antibiotics (usually flucloxacillin or
erythromycin)

Incision and drainage is required for furunculosis. (progressed folliculitis)

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8
Q

What is the difference between a furuncle and a carbuncle?

A

A furuncle is a deep follicular abscess
- Involvement with adjacent connected follicles = Carbuncle

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9
Q

What is a carbuncle more likely to lead to than a furnucle?

A

Carbuncle - more likely to lead to complications such as cellulitis and septicaemia

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10
Q

Why do some people develop recurrent staph impetigo or recurrent furunculosis?

A

Establishment as a part of the resident microbial flora (in reservoirs)
- Abundant in nasal flora

Immunodeficiency
- Hypogammaglobulinaemia
- Hyper IgE syndrome – deficiency
- Chronic granulomatous disease
- AIDS
- Diabetes Mellitus

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11
Q

What is impetigo?

A

Impetigo (also called pyoderma) is a superficial bacterial skin infection that is highly contagious. Impetigo can be caused by Streptococcus pyogenes and Staphylococcus aureus.

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12
Q

What does staphylococcus aureus express?

A

expresses virulence factors that confer pathogenic properties

such as…
- haemolysin
- PVL
- leukocidin
- alpha toxin

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13
Q

What can staphylococcus aureus cause?

A

ecthyma
impetigo
cellulitis
folliculitis
- furunculosis
- carbuncles

staphylococcal scalded skin syndrome (SSSS)

superinfects other dermatoses (e.g., atopic eczema, HSV, leg ulcers)

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14
Q

What is PVL short for and what does it do?

A

panton valentine leukocidin

pathogenic factor that leukocyte destruction and tissue (necrosis)

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15
Q

What is Panton Valentine leukocidin
Staphylococcus Aureus (PVL)?

A

beta pore forming exotoxin

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16
Q

What does PVL increase when it comes to infections?

A

higher morbidity, mortality, transmissibility

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17
Q

What does PVL Staphylococcus Aureus do and to what on the body?

A

skin
- recurrent and painful abscesses
- folliculitis
- cellulitis

extracutaneous:
- Necrotising pneumonia
- Necrotising fasciitis
- Purpura fulminans

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18
Q

What is the virulence of Streptococcus?

A
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19
Q

What increases the risk of acquiring panton valentine leukocidin staphylococcus aureus?

A

5 Cs

Close Contact – e.g. hugging, contact sports

Contaminated items , e.g. gym equipment, towels or razors.

Crowding –crowded living conditions such as e.g. military accommodation, prisons and boarding schools.

Cleanliness (of environment)

Cuts and grazes – having a cut or graze will allow the bacteria to enter the body

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20
Q

What is the treatment for Panton Valentine Leukocidin Staphylococcus Aureus?

A

Consult local microbiologist / guidelines

Antibiotics (often tetracycline)

Decolonisation – often:
- Chlorhexidine body wash for 7 days
- Nasal application of mupirocin ointment 5 days)

Treatment of close contacts

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21
Q

What is pseudomonal folliculitis?

A
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22
Q

What is cellulitis?

A

Infection of lower dermis and subcutaneous tissue

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23
Q

What happens during cellulitis?

A

Tender swelling with ill-defined, blanching erythema or oedema

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24
Q

What are most cases of cellulitis caused by?

A

Most cases: Streptococcus pyogenes & Staphylococcus aureus

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25
Q

What is a predisposing factor of cellulitis?

A

Oedema is a predisposing factor

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26
Q

What is the treatment for cellulitis?

A

systemic antibiotics

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27
Q

What is impetigo?

A

Superficial bacterial infection, stuck-on, honey-coloured crusts overlying an erosion.

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28
Q

What causes impetigo?

A
  • Streptococci
    or
  • Staphylococci
    Caused by exfoliative toxins A & B, split epidermis by targeting desmoglein I
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29
Q

What is the impetigo by streptococci?

A

non-bullous

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30
Q

What is the impetigo by staphylococci?

A

bullous

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31
Q

What does impetigo often affect?

A

face (perioral, ears, nares)

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32
Q

How is impetigo treated?

A

Treated with topical +/- systemic antibiotics.

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33
Q

When does impetiginization occur?

A

Occurs in atopic dermatitis
- Gold crust
- Staphylococcus aureus

impetiginized eczema

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34
Q

Is lyme disease bacterial or viral?

A

bacterial

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35
Q

What is another word for lyme disease?

A

borreliosis

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36
Q

What is borreliosis (lyme disease)?

A

Annular erythema develops at -
site of the bite of a Borrelia- infected tick

  • ring like in the picture
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37
Q

What do the bites from lyme disease form?

A

ixodes

*most patients don’t remember being bitten

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38
Q

What is the tick infected with in lyme disease?

A

Borrelia burgdorferi

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39
Q

What is the initial cutaneous manifestation of lyme disease?

A

Erythema migrans (only in 75%)

  • Erythematous papule at the bite site
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40
Q

What does the erythematous papule progress to in lyme disease?

A

Progression to annular erythema of >20cm

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41
Q

What happens 1-30 days after infection in lyme disease?

A

fever and headache

Multiple secondary lesions develop - similar but smaller to initial lesion

Neuroborreliosis
- Facial palsy / other CN palsies
- Aseptic meningitis
- Polyradiculitis

Arthritis – painful and swollen large joints (knee is the most affected join)

Carditis

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42
Q

What are the investigations for lyme disease (borreliosis)?

A

Serology not sensitive

Histopathology - non-specific

High index of suspicion required for diagnosis

treat w/out certainty, bc the risk of progression is worse than rik of antibiotics

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43
Q

Why don’t you perform a biopsy for borreliosis?

A

bc it’s non specific for lyme disease

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44
Q

Is syphilis bacterial or viral?

A

bacterial

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45
Q

What is the bacteria that causes syphillis?

A

Treponema pallidum

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46
Q

What is the primary infection like for syphillis?

A

Chancre (a single ulcer)
painless ulcer with a firm indurated border

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47
Q

What happens 1 week after the primary chancre in syphillis?

A

painless regional lymphadenopathy

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48
Q

When does the chancre appear for syphilis?

A

chancre appears within 10-90 days

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49
Q

What happens if syphilis is left untreated?

A

Secondary syphilis

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50
Q

When does secondary syphilis begin?

A

50 days after chancre

51
Q

What happens during secondary syphilis?

A

Malaise, fever, headache, pruritus, loss of appetite, iritis

  • Rash (88-100%) -Pityriasis rosea-like rash
  • Alopecia (‘moth-eaten’)
  • Mucous patches
  • Lymphadenopathy
  • Residual primary chancre
  • Condylomata lata
  • Hepatosplenomegaly

*‘Great mimicker’ – low threshold for testing

52
Q

What is a rare manifestation of secondary syphilis?

A

lues maligna

53
Q

What is lues maligna?

A

Pleomorphic skin lesions with pustules, nodules and ulcers with necrotising vasculitis

54
Q

Where is lues maligna more frequent?

A

in HIV manifestation

55
Q

What is tertiary syphilis?

A

it can destroy nasal cartilage, because it can happen over cartilage destroying it

56
Q

How do you diagnose syphilis?

A

● Clinical findings
● Serology

Strong index of suspicion required in 2ndary syphilis

57
Q

What is the treatment for syphilis?

A

IM benzylpenicillin or oral tetracycline

58
Q

What is the only virus you need to know in derm?

A

herpes simplex virus

59
Q

What are all the bacterial infections you need to know for derm? (6)

A

folliculitis
cellulitis
pseudomonal foliculitis
impetigo
Borreliosis (lyme disease)
Syphilis

60
Q

What is herpes simplex virus?

A

Primary and recurrent vesicular eruptions

61
Q

What does herpes favour?

A

Favour orolabial and genital regions

62
Q

What I transmission of herpes not limited to?

A

Transmission can occur even during asymptomatic periods of viral shedding

63
Q

What are the types of herpes simplex virus, and how can they be transmitted?

A

● HSV-1 – direct contact with contaminated saliva / other infected secretions

● HSV-2 - sexual contact

64
Q

Where does herpes replicate?

A

Replicates at mucocutaneous site of infection

65
Q

How does herpes simplex virus travel?

A

Travels by retrograde axonal flow to dorsal root ganglia

travels back down (anterograde) to cause flare ups

66
Q

When do symptoms of herpes occur?

A

with 3-7 days of exposure

67
Q

What happens before the symptoms in herpes?

A

Preceded by tender lymphadenopathy, malaise, anorexia
± Burning, tingling

68
Q

What are the symptoms of herpes?

A

Painful rouped vesicles on erythematous base → ulceration / pustules / erosions with scalloped border

Crusting

Orolabial lesions – often asymptomatic

Genital involvement – often excruciatingly painful→ urinary retention

69
Q

When does crusting resolve in herpes?

A

2-6 weeks

70
Q

What happens when there is reactivation of herpes?

A

spontaneous, UV, fever, local tissue damage, stress

71
Q

What are the symptoms of herpes (google)?

A

Pain or itching around the genitals.
Small bumps or blisters around the genitals, anus or mouth.
Painful ulcers that form when blisters rupture and ooze or bleed.
Scabs that form as the ulcers heal.
Painful urination.
Discharge from the urethra, the tube that releases urine from the body.
Discharge from the vagina.

72
Q

What are the systemic manifestations of herpes simplex virus?

A

aseptic meningitis in up to 10% of omen

73
Q

What is an emergency in herpes?

A

Eczema herpeticum
- emergency
- Monomorphic,
punched out erosions (excoriated vesicles)

  • give IV antivirals (acyclovir)
74
Q

What happens more in HSV-1 than HSV-2?

A
75
Q

What is herpetic whitlow often misdiagnosed as?

A

paronychia or dactylitis

76
Q

In who does herpetic whitlow occur most in?

A

children

77
Q

What is the danger of giving birth if you have herpes?

A

Neonatal HSV infection

78
Q

What happens during neonatal HSV infection?

A

Exposure to HSV during vaginal delivery – risk higher when HSV acquired near time of delivery

HSV 1 or 2

79
Q

When does onset of neonatal HSV infection start?

A

onset from birth to 2 weeks

80
Q

Where is neonatal HSV infection usually localised?

A

scalp or trunk

81
Q

What are the symptoms of neonatal HSV infections?

A

Vesicles → bullae erosions

82
Q

What is the mortality like for neonatal HSV infection and what does it require to be treated?

A

Encephalitis → mortality >50% without treatment, 15% with treatment → neurological deficits

requires IV antivirals

83
Q

Give an example of where there can be variable manifestations of Herpes?

A

immunocompromised patients such as HIV or transplant recipients (they have chronic ulcers and wart like lesions)

84
Q

What is the most common presentation of herpes?

A

chronic, enlarging ulceration

it can be multiple sites or disseminated

85
Q

Give examples of how herpes is often atypical?

A

verrucous, exophytic or pustular lesions

86
Q

What may herpes start affecting?

A

Respiratory or GI tracts

87
Q

How do you diagnose for herpes?

A

swab for polymerase chain reaction

88
Q

How do you treat herpes?

A

Don’t delay

Oral valacyclovir or acyclovir 200mg five times daily in immunocompetent localised infection
- Intravenous 10mg/kg 3 times a day X 7-19 days

89
Q

How can you classify fungal infections?

A

superficial
depp/ soft tissue
disseminated

90
Q

What is an example of a superficial fungal infection?

A

Pityriasis versicolor

91
Q

What fungus causes Pityriasis versicolor?

A

malassezia

92
Q

What does Pityriasis versicolor cause?

A

Hypopigmented, hyperpigmented or erythematous macular eruption +/- fine scale
- more noticeable when tanned

93
Q

When does Pityriasis versicolor begin?

A

Begins during adolescence (when
sebaceous glands become active)

94
Q

When are there flares of Pityriasis versicolor?

A

Flares when temperatures and humidity are high – Immunosuppression

95
Q

How do you treat pityriasis versicolor?

A

topical versicolor

96
Q

What are dermatophytes? And what type of fungal infection do they cause?

A

fungi that live on keratin

superficial fungal infection

97
Q

What is are examples of dermatophytes and what do they cause the most of?

A

Trichophyton rubrum causes the most fungal infections

Trichophyton tonsurans causes the most tinea capitis

98
Q

What is a kerion?

A

an inflammatory fungal infection that may mimic a bacterial folliculitis or an abscess of the scalp; scalp is tender and patient usually has posterior cervical lymphadenopathy

99
Q

What are kerions frequently secondarily infected with?

A

staphylococcus aureus

100
Q

What is an Id reaction?

A

Aka Dermatophytid reactions

Inflammatory reactions at sites distant from the associated dermatophyte infection

101
Q

What may an Id reaction include?

A

May include urticaria, hand dermatitis, or erythema nodosum

102
Q

What is an Id reaction likely secondary to?

A

likely secondary to a strong host immunologic response against fungal antigens

103
Q

What is candidiasis?

A

candida albicans

104
Q

What do most sites of candidiasis show?

A

most sites show erythema oedema, thin purulent discharge

105
Q

What is an example of an opportunistic fungal infection (the only one you need to know)?

A

Mucormycosis

106
Q

What is the presentation of mucormycosis?

A

oedema, then pain, then eschar

107
Q

What are the symptoms of mucormycosis?

A

fever, headache proptosis, facial pain, orbital cellulitis ± cranial nerve dysfunction

108
Q

What are the fungi that can cause Mucormycosis?

A

Apophysomyces, Mucor, Rhizopus, Absidia, Rhizomucor

109
Q

What is Mucormycosis associated with?

A

Diabetes mellitus (1/3 of patients - Diabetic ketoacidosis very high risk)

Malnutrition
Uraemia
Neutropaenia
Medications: Steroids / antibiotics / desferoxamine
Burns
HIV

110
Q

What is the treatment for Mucormycosis?

A

aggressive debridement & antifungal therapy amphotericin

111
Q

What pathogen causes scabies?

A

parasite

112
Q

What is scabies?

A

Contagious infestation caused by Sarcoptes species

113
Q

How does sarcoptes work for scabies to occur?

A

Female mates, burrows into upper epidermis, lays her eggs and dies after one month.

114
Q

What is the onset like for scabies?

A

Insidious onset of red to flesh-coloured pruritic papules

An insidious disease is any disease that comes on slowly and does not have obvious symptoms at first

115
Q

What areas of the body does scabies affect?

A

Affects interdigital areas of digits, volar wrists, axillary areas, genitalia

v itchy

116
Q

What does scabies look like?

A

A diagnostic burrow consisting of fine white scale

Crusted or ‘Norwegian’ scabies - hyperkeratosis

often asymptomatic in immunocompromised individuals

117
Q

How do you treat scabies?

A

permethrin, oral ivermectin
- Two cycles of treatment are required

118
Q

What is folliculitis?

A

inflammation of the hair follicles

119
Q

How does staphylococcal impetigo manifest on the skin?

A

as small blisters that burst to leave a yellow, crusty coating

120
Q

How does borreliosis manifest on the skin?

A

as a single, expanding red rash often resembling a bull’s-eye

121
Q

How does HSV infection manifest in new-borns?

A

as small grouped vesicles on a red base, often accompanied by systemic symptoms

122
Q

What is the name of the fungus responsible for causing pityriasis versicolor?

A

malassezia furfur

123
Q

How does scabies manifest on the skin?

A

as a fine, red rash accompanied by intense itching, especially at night

BRS DERMATOLOGY (8 decks)

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