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Derm 2020 > Infections - Mycobacterial > Flashcards

Infections - Mycobacterial Flashcards

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Dermatology Board Prep flashcards
1
Q

What are the slow growing mycobacteria

A 
KMATS 
M. Kansasi
M. Marinum
M. Avium
M. TB
M. Scrofulaceum
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2
Q

M. Leprae is a very small slightly curved rod

A

True

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3
Q

Which are fast growing mycobacteria

A 
FACD
M. Fortuitum
M. Abscessus
M. Chelonae
M. GooDii
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4
Q

A minority of exposed individuals do not develop leprosy

A

False majority

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5
Q

WHO Classificatoin of Leprosy

A

1 - paucibacillary, single lesion Leprosy
2 - paucibacillary, 2-5 skin lesions
3 - multibacillary

Not as commonly used as the LL/BL/BB/BT/TT/I classification

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6
Q

What are clinical features of lepromatous leprosy

A 
LEPROSY
Leonine facies
Eyes - lagophthalmos, eyebrows (madarosis)
Peripheral and sensory neuropathy (foot drop) - in BT/TT
Resorption of bone (shortened digits)
Orchitis and sterility
Saddle nose
Y (Gynaecomastia, IchthYosis)

Form with least cellular immunity and greatest number of bacilli
- multiple poorly defined erythematous macules, papules, nodules and plaques
- lesions are widespread and USUALLY symmetric
Most common sites are the face, buttock and lower extremities
Infiltration of the skin of forehead can lead to leonine facies
- additional signs and late sequelae:
—> madarosis of eyebrows
—> saddle nose
—> enlarged earlobes
—> acquired ichthyosis on Lower extremities
Anaesthesia in glove and stocking distribution
Lagophthalmos

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7
Q

Histoid leprosy is characterised by the development of dermatofibroma-like papules and nodules

A

True

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8
Q

Clinical features of borderline leprosy

A

Features intermediate between two ends of spectrum - cutaneous lesions are usually symmetric

  • may have unilateral earlobe swelling
  • severity of cutaneous and pierhpheral nervous system abrnoalities depend on whether pt “leans” towards BT or BL pole
  • within cutaneous plaques, hairs are usually ABSENT
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9
Q

Clinical features of Tuberculoid leprosy

A

Borders of skin lesions are slightly elevated -this is the preferred site for histologic exam

  • seen only a few well demarcated plaques and sometimes only NEURAL involvement
  • in some patients, they are hypopigmented plaques
  • typically partial bu not complete pigment loss
  • plaques need to be examined for alopecia as well as anesthesia or hypostheisa
  • unilateral neuropathic changes eg. Digital resorption may be seen
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10
Q

Leprosy reactions - type 1

A

Reversal reaction with “upgrading”
- enhancement of cell mediated immunity with a Th1 cytokine pattern
- delayed type hypersensitivity reaction
Occurs with BT, BB or BL or tuberculoid leprosy with immunologic recovery during or after tx
- PINE (lone pine type 1)
—> P: acute nerve pain or tenderness (neuritis) and loss of function
—> I: incr inflammation in established skin lesions
—> N: neurological impairment in absence of painful nerves
—> E: emergence of new lesions of the skin
—>
—>
—>

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11
Q

Leprosy reaction type 2 - excessive humoral immunity with a Th2 cytokine pattern and formation of immune complexes, may be accompanied by increased cell mediated immunity

A

True

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12
Q

Features of type 2 leprosy reaction

A 
erythema nodosum leprosum most common
FLOSHING
- fever
- lymphadenitis  
- orchitis
- severe joints welling and pain
- hepatosplenomegaly
- iridocyclitis 
- nodular skin lesions
- glomerulonephritis
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13
Q

What is Lucio phenomenon

A

Reactional state characterised by thrombotic phenomena in addition to necrotising cutaneous small vessel vasculitis

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14
Q

Grenz zone on histo

A

True

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15
Q

Virchow cells and granulomas can be seen in indeterminate form

A

False

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16
Q

What are Virchow cells

A

Macrophages with numerous bacilli as well as lipid droplets in their cytoplasm

17
Q

WITH NERVE INVOLVEMENT, CUTANEOUS NERVES SHOW LAMINATION OF THE PERINEURIUM, CAUSING AN ONION SKIN APPEARANCE

A

TRUE

18
Q

WHAT STAINs can be used to help diagnose leprosy

A 
Gram stain
Ziehl-Nielsen
Wade-Fite
Methanamine silver is good for detecting fragmented AFB 
Sudan III and Sudan IV
19
Q

How to perform a slit skin smear

A

Samples can be obtained from earlobes, chin, extensors forearms, dorsal fingers , buttocks and trunk
- fold of skin is firmly squeezed between thumb and forefinger of examiner with forceps
Small incision made with a scalpel bald
Liquid nitrogen is smeared onto a slide + allowed to dry
Smear is usually stained by the FITE or Z-N method and search made for red rods at 100 x with oil immersion
Organisms can be found in 100% of those with lepromatous leprosy, 75% of those with borderline leprosy and 5% of those with suspected tuberculoid leprosy

20
Q

What are the 3 classic skin tests with leprosy (now infrequently used)

A
  • histamine - 0.001% histamine placed on suspect patch and another on normal skin as control. Both sites are pricked with needle then extent of wheal and flare is recorded.
  • pilocarpine - tincture of iodine applied to suspected lesion and normal skin prior to injection of pilocarpine
    —> areas then dusted with starch will turn blue ., if normal sweating, as sweating is decreased in lesions of leprosy since relies on parasympathetic nerve fibres
  • Lepromin test intradermal injection of 0.1mL suspension of heat killed. M. Leprae
21
Q

Treatment of paucibacillary leprosy

A

Daily Dapsone 100mg
Monthly rifampin 600mg
For 6 months

22
Q

Treatment of multibacillary leprosy

A

Monthly Rifampicin 600mg and clindamycin 300mg + daily clofazimine 50mg and dapsone 100mg, for 12 months

23
Q

TB subtypes

A 
TB chancre
TB verrucosa cutis
Scrofuloderma
Orificial TB
Lupus vulgaris
Miliary TB
TB gumma
Papulonecrotic tuberculid
Lichen scrofulosorum
Erythema induratum
24
Q

M. Ulcerans is caused by a slow growing mycobacteria

A

True

25
Q

Mycobacterium is thought to be harboured by snails, water insects, fish and aquatic plants

A

True

26
Q

Organisms are found at edge but not base of ulcers of M.ulcerans

A

False within base and surrounding necrotic tissue

27
Q

M. Ulcerans are very painful

A

False . Painless due to mechanism of inhibiting pain receptors by binding to angiotensin II type 2 receptors on neurons

28
Q

M ulcerans lesions do not tend to spontaneously resolves

A

False can resolve over 6-9 mo

29
Q

BCG vaccine provides no immunity towards M ulcerans

A

False - emerging evidence it may protect against Buruli ulcers and osteomyelitis in the short term

30
Q

M ulcerans patients are usually unwell

A

False usually well

31
Q

Clarithromycin is first line for m. Marinum

A

True

32
Q

Sporotrichoid spread in which mycobacteria?

A 
FKMS
Fortuitum
Kansasi
Marinum
Scrofulaceum

Derm 2020 (59 decks)

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