Infections - Mycobacterial 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

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

25
Mycobacterium is thought to be harboured by snails, water insects, fish and aquatic plants
True
26
Organisms are found at edge but not base of ulcers of M.ulcerans
False within base and surrounding necrotic tissue
27
M. Ulcerans are very painful
False . Painless due to mechanism of inhibiting pain receptors by binding to angiotensin II type 2 receptors on neurons
28
M ulcerans lesions do not tend to spontaneously resolves
False can resolve over 6-9 mo
29
BCG vaccine provides no immunity towards M ulcerans
False - emerging evidence it may protect against Buruli ulcers and osteomyelitis in the short term
30
M ulcerans patients are usually unwell
False usually well
31
Clarithromycin is first line for m. Marinum
True
32
Sporotrichoid spread in which mycobacteria?
``` FKMS Fortuitum Kansasi Marinum Scrofulaceum ```