Skin infestations and infections 4 Flashcards
How many different types of HPV (warts) are there?
> 200 subtypes of HPV
What are examples of superficial fungal infections?
- Candida
- Malassezia
- Dermatophytes
What are examples of deep/soft tissue fungal infections?
- Chromomycosis
2. Madura foot
What are examples of disseminated fungal infections?
- Candida
- Aspergillus
- Fusarium
- Histoplasma
- Coccidiodes
- Blastomycosis
- Mucormyocis
What is pityriasis versicolor?
Hypopigmented, hyperpigmented or erythematous macular eruption +/- fine scale
When does pityriasis versicolor begin? What is it caused by?
- Malassezia spp.
* Begins during adolescence (when sebaceous glands become active)
When does pityriasis versicolour flare up?
when temperatures and humidity are high – Immunosuppression
What is the treatment for pityriasis versicolour?
Topical azole
What are dermatophytes?
fungi that live on keratin
What causes the most fungal infections?
Trichophyton rubrum
What causes the most tinea capitis?
Trichophyton tonsurans
What is kerion?
- 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
What is tinea pedis Trichophyton rubrum?
scaling and hyperkeratosis of plantar surface of food
What is tinea pedis Trichophyton mentagrophytes (interdigitale)?
sometimes vesiculobullous reaction on arch or side of foot
What is an Id reaction?
Dermatophytid reactions
What happens in an Id reaction?
- inflammatory reactions at sites distant from the associated dermatophyte infection
- may include urticaria, hand dermatitis, or erythema nodosum
What can an id reaction be secondary to?
to a strong host immunologic response against fungal antigens
What is majocchi granuloma?
Follicular abscess produced when dermatophyte infection penetrates the follicular wall into surrounding dermis; tender
What is the usual culprit for majocchi granuloma?
Trichophyton rubrum or mentagrophytes
What is candidiasis predisposed by?
- Candida albicans
* by occlusion, moisture, warm temperature, diabetes mellitus
What do most sites of candidiasis show?
erythema oedema, thin purulent discharge
Where does candidiasis usually happen?
an intertriginous infection (affecting the axillae, submammary folds, crurae and digital clefts) or of oral mucosa
What can candidiasis affect?
- common cause of vulvovaginitis
- can affect mucosae.
- become systemic (immunocompromise)
What are deep fungal infections?
- Capacity for deep invasion of skin or production of skin lesions secondary to systemic visceral infection
- Subcutaneous fungal infections – infections of implantation (inoculation)
What can cause deep fungal infections?
- Sporotrichosis
- Phaeohypomycosis
- Chromomycosis
- Mycetoma (Madura foot)
- Lobomycosis
- Rhinosporidiosis
What do systemic respiratory endemic fungal infections include?
- blastomycosis
- histoplasmosis
- coccidiodomycosis
- paracoccidoiodomycosis
- penicillinosis
When can you get systemic fungal infection?
in both immunocompetent and immunosuppressed
What are the risk factors for aspergillosis?
- neutropaenia
- corticosteroid therapy
What is aspergillosis primarily?
respiratory pathogen
What does aspergillosis look like?
- Cutaneous lesions being as well-circumscribed papule with necrotic base and surrounding erythematous halo,
- Propensity to invade blood vessels causing thrombosis and infarction
What can the lesions be like in aspergillosis?
- Lesions destructive – may extend into cartilage, bone and fascial planes
- Should be considered in differential of necrotisiing lesions
What is fusarium?
causes similar illness and cutaneous lesions both clinically and histologically – (septate hype with acute angle branching)
What is primary cutaenous aspergillosis characterised by?
- hyperpigmented plaques with brown–black scale-crusts at the site of intravenous catheters on the arm
- (A);Necrotic hemorrhagic bulla due to embolus of Aspergillus flavus (D)
What is mucormycosis caused by?
Apophysomyces, Mucor, Rhizopus, Absidia, Rhizomucor
What are the associations with mucormycosis?
- 1/3 of patients have diabetes, those in DKA are at particularly high risk
- malnutrition
- uraemia
- neutropaenia
- steroid therapy
- burns
- antibiotic therapy
- neonatal prematurity
- deferoxamine therapy
- HIV
What is the presentation of mucormycosis?
- fever, headache, facial oedema, proptosis, facial pain, orbital cellulitis, cranial nerve dysfunction
- +/- nerve dysfunction due to retinal artery thrombosis
What is the treatment of mucormycosis? When is the culture positive?
- aggressive debridement and antifungal therapy
2. Culture positive in only 30% of cases
What is scabies caused by?
contagious infestation caused by Sarcoptes species
What happens in scabies?
Female mates, burrows into upper epidermis, lays her eggs and dies after one month.
How does scabies present?
- Insidious onset of red to flesh-coloured pruritic papules
- diagnostic burrow consisting of fine white scale is often seen
What does scabies affect?
- interdigital areas of digits
- volar wrists
- axillary areas
- genitalia
What is Norwegian scabies?
- Crusted or ‘Norwegian’ scabies - hyperkeratosis
2. Often asymptomatic; found in immunocompromised individuals
What is the treatment of scabies?
- permethrin, oral ivermectin
2. two cycles of treatment are required
What is head louse caused by?
Pediculus humanus capitis
What is head louse?
- Entire live cycle spent in hair
- 2ndary infection common
What is the treatment of head louse?
malathion, permethrin, or oral ivermectin
What is body louse?
Pediculus humanus corporis
What does body louse look like?
- Lives and reproduces in clothing – leaves to feed; rarely found on skin
- Pruritic papules & hyperpigmentation
When is body louse common?
vercrowding, poverty & poor hygiene
How do you treat body louse?
thorough cleaning or discarding clothes
What is pubic louse?
Phithrus pubis aka crabs; three pairs of legs
Where are eggs found in pubic louse?
hair shaft, also found in occipital scalp, body hair, eyebrow and eyelash, axillary hair
What is the treatment for pubic louse?
malathion / permethrin, oral ivermectin
What are bedbugs?
- Cimex lectularius – reddish-brown, wingless insect resembling size and shape of ladybird
- Itchy weals around a central punctum
Where are bedbugs?
- Dine alone at night, rapidly and painlessly
* Live behind wallpaper, under furniture
How do you treat bedbugs?
- Fumigation of home is necessary to get rid of pest
* Treatment of patient is symptomatic
