skin infections and infestations basics

Question 1

things caused by staphylococcus aureus

Answer 1

impetigo
folliculitis
cellulitis
ecthyma
staohylococcal scalded skin syndrome
superinfections of other skin diseases e.g leg ulcers, atopic eczema

Question 2

What immune deficiencies make you more prone to bacterial infections?

Answer 2

Hypogammaglobulinaemia

HyperIgE syndrome

AIDS

Diabetes Mellitus

Question 3

conditions caused by streptococcus pyogenes

Answer 3

impetigo
cellulitis
ecthyma
eysipelas
scarlet fever
necrotising fasciitis
superinfects other skin diseases e.g leg ulcers

Question 4

PVL toxin - panton valentine leukocidin

Answer 4

s.aureus toxin
pore forming, painful, multi site, recurrent and present in contact
painful
necrotising fasciitis, pneumonia, purpura fulminans

Question 5

preventing PVL infection

Answer 5

close contact
contaminated items
crowding
cleanliness
cuts

Question 6

treatment of PVL infection

Answer 6

antibiotics
nasal mupirocin ointment
chlorhexidine body wash
treat any contacts

Question 7

what is folliculitis

Answer 7

follicular erythema, can be pustular
infections or non infectious (HIV)

treated by antibiotics - erythormicin
incision and drainage for furunculosis (large)

Question 8

what is pseudomonal folliculitis (hot tub)

Answer 8

pseudomonas aeruginosa
associated w moisture, 1-3 days post exposure to hottub etc
self limiting

Question 9

furuncle vs carbuncle

Answer 9

furuncle - deep abcess of one follicle

carbuncle - deep abscess of several adjacent follicles (can cause cellulitis or septicaemia)

Question 10

what is cellulitis

Answer 10

infection of lower dermis/subcut
tender swelling with ill defined blanching erythema/odemea
usually strep pyogenes or s.aureus
odema predisposes
treated by systemic antibiotics

Question 11

what is impetigo

Answer 11

superficial bac infection, honey coloured crust
caused by staphylococcus
affects face
treated with topical and systemic antibiotics

Question 12

what is impetiginisation

Answer 12

infection of atopic eczema

staph aureus
gold crust

Question 13

what is lyme disease (borreliosis)

Answer 13

target shaped (annular erythema)
infected tick bite
carditis and arthritis and neuroborriolis (facial palsy, aseptic meningitis, polyradiulitis)

Question 14

what is the initial presentation of syphilis?

Answer 14

Primary infection Chancre -painless ulcer with a firm indurated border
Painless regional lymphadenopathy one week after the primary chancre
Chancre appears within 10-90 days

Question 15

What is secondary syphilis, what are the symptoms?

Answer 15

Begins 50 days after chancre
Presents with malaise, fever, headache, pruritus, loss of appetite, iritis

Question 16

Why is syphilis referred to as the great mimicker?

Answer 16

Presents with a wide range of symptoms such as
Rash
Alopecia
Mucous patches
Lymphadenopathy
Residual primary chancre
Hepatosplenomegaly

Question 17

What is lues maligna in syphilis?

Answer 17

Rrae manufestation of secondary syphilis

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

More frequent in HIV manifestations

Question 18

What is tertiary syphilis?

Answer 18

Gumma skin lesions - nodules and plaques

Extend pripherally while central areas heal with scarring and atrophy

Mucosal lesions extend and destroy the nasal cartilage

Cardiovascular disease

Neurosyphilis

Question 19

How is syphilis diagnosed?

Answer 19

Clinal findings
Serology
Strong index of suspicion required in secondary syphilis

Question 20

What is the treatment for syphilis?

Answer 20

IM benzylpenicilin or oral tetracycline

Question 21

What is herpes simplex virus?

Answer 21

Primary and recurrent vesicular eruptions favouring orolabial and genital regions

Travels by retrograde axonal flow to dorsal root ganglia

Question 22

What are the two types of HSV?

Answer 22

HSV-1 – direct contact with contaminated saliva / other infected secretions
HSV-2 - sexual contact

Question 23

What is HSV preceded by?

Answer 23

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

Question 24

What may cause reactivation of HSV?

Answer 24

Reactivation – spontaneous, UV, fever, local tissue damage, stress

Question 25

What is the systemic manifestation of HSV?

Answer 25

aseptic meningitis in 10% of omen

Question 26

What is eczema herpeticum?

Answer 26

Emergency Monomorphic punched or erosions (excoriated vesicles)

Question 27

What is herpetic whitlow?

Answer 27

HSV (1>2) infection of digits – pain, swelling and vesicles (vesicles may appear later) Misdiagnosed as paronychia or dactylitis Often in children

Question 28

What causes neonatal HSV?

Answer 28

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

Question 29

what are some features of neonatal HSV?

Answer 29

HSV 1 or 2 Onset from birth to 2 weeks Localised usually – scalp or trunk Vesicles → bullae erosions Encephalitis → mortality >50% without treatment, 15% with treatment → neurological deficits Requires IV antivirals

Question 30

What is severe or chronic HSV, how does it present, other involvements?

Answer 30

Immunocompromised patients e.g. HIV / transplant recipient Most common presentation – chronic, enlarging ulceration Multiple sites or disseminated Often atypical e.g. verrucous, exophytic or pustular lesions Involvement of respiratory or GI tracts may occur

Question 31

How is HSV diagnosed?

Answer 31

Swab for PCR

Question 32

What is the treatment for HSV?

Answer 32

Don’t delay Oral valacyclovir or acyclovir 200mg five times daily in immunocompetent localised infection Intravenous 10mg/kg TDS X 7-19 days

Question 33

What is pityriasis versicolor?

Answer 33

Superficial fungal infection Hypopigmented, hyperpigmented or erythematous macular eruption +/- fine scale Malassezia spp.

Question 34

When does pityriasis versicolor tend to begin?

Answer 34

Adolescence when sebaceous glands become active

Question 35

What causes flares in pityriasis versicolor?

Answer 35

When temperatures and humidity are high

Question 36

Treatment for pityriasis versicolor?

Answer 36

Topical azole

Question 37

What are dermatophytes?

Answer 37

Fungi that live on keratin

Question 38

What two fungi cause the most fungal infections and tinea capitis?

Answer 38

Trichophyton rubrum and trichophyton tonsurans

Question 39

What is a kerion?

Answer 39

– 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 - Frequently secondarily infected with Staphylococcus aureus

Question 40

What are Id reactions?

Answer 40

Dermatophytid reactions Inflammatory reactions at sites distant from the associated dermatophyte infection May include urticaria, hand dermatitis, or erythema nodosum Likely secondary to a strong host immunologic response against fungal antigens

Question 41

What is the a common cause of vulvovaginitis?

Answer 41

Candiasis

Question 42

What is candidiasis predisposed by?

Answer 42

occlusion, moisture, warm temperature, diabetes mellitus

Question 43

What are the usual presentations of candidiasis?

Answer 43

Most sites show erythema oedema, thin purulent discharge Usually an intertriginous infection (skin folds) or of oral mucosa.

Question 44

What type of fungal infection is mucormycosis?

Answer 44

Opportunistic

Question 45

Typical presentation of mucormycosis?

Answer 45

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

Question 46

What is mucormycosis associated with?

Answer 46

Diabetes mellitus (1/3 of patients - DKA very high risk Malnutrition Uraemia Neutropaenia Medications: Steroids / antibiotics / desferoxamine Burns HIV

Question 47

What is the treatment for mucormycosis?

Answer 47

aggressive debridement & antifungal therapy amphoteracin

Question 48

What is scabies?

Answer 48

Contagious infestation caused by Sarcoptes species Female mates, burrows into upper epidermis, lays her eggs and dies after one month. Insidious onset of red to flesh-coloured pruritic papules

Question 49

Where does scabies usually affect?

Answer 49

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