Uncommon Infections Flashcards
What are the uncommon infections of the skin?
- Parasites
- Mycobacterium Diseases including Leprosy
- HIV Infection
What are the 3 main types of parasites?
- Arthropods
- Worms
- Protozoa
For what are the parasitical arthropods?
- Lice
- Ticks
- Arachnids
For what are the parasitical worms?
- Roundworms (Hookworms, pinworms)
- Onchocerciasis
- Schistosomiasis
What is this and what causes it?
Erythema Chronicum Migrans
It is caused by Borrelia Burgdorferi (A spriochete - type of bacteria)
It is transmitted by ticks.
Describe the different forms wereby Erythema Migrans can present.
What can happen if the Lyme’s disease is undiagnosed or treated?
- Neurological complications
- Rarely
- Arthritis
- Cardiac Disease
What is a late manifestation of of Lyme’s Disease?
Acrodermatitis chronica atrophicans (Scleroderma like rash)
It affects the distal parts of the body - due to chronic Borrelia Burgdorferi infection.
What is the investigation for lyme’s disease?
What is interesting about this investigation?
Borrelia serology
(it may take several months to be postive)
What would be the clinical picture if someone had skin disease due to worms?
- Pruritus
- Bloods - eosinophilia
- History of foreign travel
For worms that affect the skin, how long can the incubation period be?
10 years
What is Onchocerciasis (“River Blindness) ?
How is it investigated and treated?
- It is a parasitic worm (Ochocerca Volvulus) from central Africa and Southern America. It causes Pruritus with urticarial and papular rashes. It can then inhabit the eyes causing blindness (blue eyes).
- Investigation: Skin snips
- Treatment: Ivermectin
What is schistosomiasis?
How is it investigated and treated?
Schistosomiasis is a parasite called Schistosoma Mansoni. It is endemic in Africa, South America, India and the Far East.. It causes itchy skin, urticaria and eosinophilia. Skin lesions are most common on the trunk and can have a zosteriform appearance.
- Investigations: stool ova/cysts/parasites may be seen on skin biopsy.
- Treatment: Mebendazole
What is Leishmaniasis?
A Protozoa found in Africa, South America.
Initially crusts, then ulcers form and then they heal.
Treatment: Pentavalent Antimony
What are some other parasites of the skin?
-
Onchocerciasis - Central Africa and South America.
- Itchy buttocks, lets, shoulders.
- Diagnose with skin snips.
- Treat with mebendazole.
- Threadworms - treat with mebendazole
- Larva currens - a larva that crawls under the skin leaves urticarial lines.
- Larva migrans - dog/cat hookorm in faeces.
What are the two types of mycobacterium?
- Atypical mycobacteria
- Mycobacterium leprae
When should cutaneous TB be suspected?
If someone is coming form an endemic area with TB and has an unusual skin lesion.
What are the ways that TB manifests in the skin?
- Lupus Vulgaris
- Warty TB
- Scrofuloderma
- Tuberculides
What is this?
How does it present?
Lupus vulgaris
- Due lymphatic/haematogenous spread from an underlying focus.
- Affects normal skin especially head/neck/face.
- Initially painless red-brown plaque with apple jelly.
- Slowly enlarges & progressively destructive.
- May be a plaque, a nodule or ulcerated.
- Regional lymphadenopathy may be present.
What is this?
Warty TB
- Presents due to re-infection in a sensitized patient usually from the far east.
- Usually occurs on the hands and feet.
What is this?
What will skin biopsies show?
Scrofuloderma
- Due to breakdown of skin overlying focus of infection.
- Usually over cervical lymph node - bluish red nodule or ulcer w fistulae.
- Haematogenous spread.
- Usually unwell with multiple bluish papules, vesicles or pustules.
- Skin biopsy shows the presence of AFBs.
What are the 2 types of tuberclides?
- Papulonecrotic tuberclides
- Erythema induratum
What type of tuberuclide is this?
Papulonecrotic tuberculide
- Cutaneous response to internal TB in a young person with good immunity.
- Lesions usually contain bacilli (on PCR) but not cultured (Not AFB)
- Recurrent symmetrical crops of non-itchy necrotising papules that heal with scarring.
- Continue for months.
- DDX is Pityriasis lichenoides acuta
What type of tuberculide is this?
How do you treat it?
Erythema induratum presents
- Crops of small tender nodules on the lower legs.
- Usually in TB patients with lung or cervical lymphadenitis.
- Treat with standard anti-TB therapy.
Name the 3 atypical mycobacteria (non-TB & non-leprosy) that affect immunosuppressed individuals and sometimes healthy individuals?
-
Mycobacterium marinum aka fish tank/swimming pool granuloma.
- Caused by water habitant especially stagnant warm water.
- Causes nodule/pustule/ulcer on hand with sporotrichoid spread.
- Heals spontaneously within a few months.
- Treated with ciprofloxacin and clarithromycin.
-
Mycobacterium ulcerans - causes Buruli ulcer found in environment.
- Ulceration down to fat.
- Treatment with surgery + antibiotics.
-
MAI complex - common in HIV skin lesions.
- Nodules, pustules, ulcers, abscesses, panniculitis other organ systems may be involved.
What is leprosy?
- Mycobacterium leprae which affects skin and peripheral nerves.
- It is readily treatable with combined antibiotic therapy but the
- immunological complications of leprosy frequently cause nerve damage even after effective antibiotic treatment.
Where in the world is leprosy usualy found?
in the Tropics and Subtropics
How do we diagnose leprosy?
It is usually diagnosed when the following features are present:
- Skin lesion typical of leprosy
- Thickening of peripheral nerves
- Acid fast bacilli in skin smear.
Describe the spectrum of Mycobacterium leprae infection
- At one end is tuberculoid disease
- A good cell mediated immunity.
- Elimate the mycobacteria but can have granulomatous damage to their skin and peripheral nerves.
- Other end - lepromatous disease
- No cell mediated immunity.
- Heavy load very much affecting nerves, skin, nasal mucosa.
- In between these ends you have Borderline Leprosy.
Which end of the spectrum of leprosy is responsible for the spread of leprosy?
(Tuberculoid disease or Lepromatous disease)
Lepromatous disease
How is treatment different between those who suffer form tuberculoid leprosy and those who suffer form lepromatous leprosy?
Treatment with antibiotics is usually shorter in Tuberculoid Leprosy
Can Mycobacterium leprae be cultured from skin biopsies?
No.
How can you test for leprosy?
Skin smears but these are quite insensitive and not specific.
Currently there are no good tests.
Describe the cutaneous manifestations of leprosy.
- Macules and plaques which occur anywhere.
-
Tuberculoid leprosy
- Lesions are usually well defined with elevated borders with central clearing.
-
Lepromatous leprosy
- Diffuse infiltration of the skin ‘Leonine Facies’.
- Skin thickens over the forehead, eyebrows. Eyelashes are lost.
- Upper incisors fal lout.
- Rhinophyma
- Diffuse infiltration of the skin ‘Leonine Facies’.
What is this?
Leonine Facies due to Lepromatous Leprosy
What is this?
Erythematous infiltrated plaque of tuberculoid leprosy
Describe the pattern of nerve damage in leprosy
- Small nerves - loss of sensation, temperature control and sweating.
- Large nerves - usually peripheral nerves - leads to muscle weakness and anaesthesia.
What peripheral nerves are most commonly affected?
- Ulnar nerve at the elbow
- Median nerve at the wrist.
- Common Peroneal nerve
What are the 5 principles of treating leprosy?
- Stop the infection with chemotherapy.
- Treat reactions.
- Educate the patient about leprosy.
- Prevent disability.
- Support the patient socially and psychologically.
How do you treat leprosy?
-
Paubacillary patients (smear negative)
- Treat for 6 months with rifampicin and dapsone.
-
Multipbacillary (Smear positive)
- Monthly rifampicin 600 mg and clofazimine 300 mg and daily dapsone 100 mg and clofazimine 50 mg
- Treat for 2 years or until smear negative.
What are the drug side effect of leproxy treatment?
- Rifampicin is only given monthly it is unusual to get side effects and problems such as induction of liver enzymes.
- Dapsone - occasionally exfoliative dermatitis.
- Clofazimine causes skin pigmentation which is reversible upon stopping the drug.
What are the 2 main types of leprosy reactions
How are they treated?
-
Type 1 or reversal reactions
- Occur in borderline patients
- Usually occurs as a result of the immune system upgarding and then whilst clearing out the bacteria - this then leads to local tissue destruction.
- Usually need high dose steroids for months.
-
Erythema Nodosum Leprosum (ENL)
- Due to immune complex deposition
- Usually have systemic illnes with fever, malaise and tender skin nodules.
- Lymphadenopathy, neuritis, bone pain, orchitis and acute iritis.
- Usually treated with thalidomide
What % of HIV patients will have skin conditions?
90%
What is the most common skin condition associated with HIV?
Seborrhoeic dermatitis
What other skin conditions afflict HIV sufferers?
Oral candidiasis
Fungal infections.
Describe the order of onset of HIV related skin disorders.
(Numbered in order of disease appearance.)
- Seborrheic dermatitis
- Herpes Zoster
- Oral Heiry Leucoplakia
- If surves
- Muco-cutaneous candidiasis
- Molluscum contagiosum
- Late stage
- Kaposi’s Sarcoma
- Ulcerating Herpes
What are the common HIV related viral skin infections?
- Molluscum contagiosum
- Herpes zoster
- Herpes simplex
- Kaposi’s sarcoma
What is the virus that causes Kaposi’s Sarcoma?
Herpes simplex virus type 8
What is this?
Kaposi’s Sarcoma
What are the 4 types of Kaposi’s Sarcoma?
- Classic Kaposi’s Sarcoma
- African Endemic Kaposi’s Sarcoma
- Iatrogenic Immunosuppressive Kaposi’s Sarcoma
- Aids-Related Kaposi’s Sarcoma
