Mycobacteria Flashcards

1
Q

Mycobacterium tuberculosis

A

airborne transmission- negative pressure rooms, N95 precautions

slow growing 6 wks to cx
mycolic acid - acid fast bacillus

Dx of TB:
Active TB: sputum x3 8 hrs apart - early morning
Acid fast stain
Cx on Lowenstein Jensen Agar
PCR

Nonpulmonary: tissue/fluid samples

Latent TB: 
1. PPD:
\+15 mm induration; 5 mm in immunosuppressed
false + with BCG vaccine
2: interferon gamma release assay
-quantiFERON gold
-T-SPOT
-don't cross react w/ BCG vaccine
-false - in HIV w/ immunosuppression
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2
Q

Primary tuberculosis

A
fever
\+/- pulm sx
CXR: mostly negative
-perihilar or R sided infiltrates
-ipsilateral hilar LAD

Ghon complex: primary infection causes CXR lesions (ghon focus) + hilar LAD

90% go to latent phase - asx or reactivate to TB
10% go to progressive infection
-local dz in lung
-miliary dissemination
-meningitis
-bone/joint dz
-gastrointestinal dz
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3
Q

Reactivation TB

A

Immune suppression

fever, night sweats, wt loss, cough, hemoptysis

CXR: infiltrates in apical - posterior segments of upper lobes

Outside of lungs:
CNS, bones, GI tract, GU, peritoneum, CV

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4
Q

Rifamycins

A

Rifampin
Rifabutin - doesn’t rev up CYP450 as much - can use w/ HIV antiretrovirals
Rifapentine - longer half life, once per week dose

4Rs:
MOA: Rna polymerase inhibitor
Revs up microsomal P450
Red-orange body fluids
Rapid Resistance if used alone

Hepatotoxicity

non TB use: prophylaxis - N. meningitidis, Hflu type B
MRSA

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5
Q

Isoniazid (INH)

A

inhibits synthesis of mycolic acid

AE: hepatotoxicity –> hepatitis

**peripheral neuropathy - give B6 pyridoxine supplements to prevent

Drug induced lupus

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6
Q

Tx for latent tuberculosis

A

isoniazid for 9 mo

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7
Q

Tx for active TB

A
2 months of "RIPE"
Rifampin
Isoniazid + Vit B6
Pyrazinamide
Ethambutol 

4 mo:
Isoniazid +Vit B6
Rifampin

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8
Q

Pyrazinamide

A

AE: hepatotoxicity

hyperuricemia - asx or gout

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9
Q

Ethambutol

A

inhibits arabinosyl transferase –> impared cell wall synthesis

AE: optic neuropathy
-Red/green color blindness
-decreased visual accuity
reversible when DC’d

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10
Q

Mycobacterium avium intercellulare (MAI) or complex (MAC)

A

pulmonary syndrome similiar to TB

immunosuppressed -AIDS –> disseminated, give prophylaxis abx azithromycin weekly begining at CD4 less than 50

Sx depends on where it spreads
-GI: abd pain, D
BM: anemia, neutropenia

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11
Q

Mycobacterium kansasii

A

pulmonary sx like TB

SX and CXR same

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12
Q

Mycobacterium marinum

A

“fish tank granuloma”

cutaneous dz from contaiminated water - swimming pools, fish tanks

enter through bounds, skin breaks

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13
Q

Mycobacterium leprae

A

Leprosy “hansen dz”

infects skin and peripheral nerves –> peripheral neuropathy, repeated trauma

ninebanded armadillo, person to person respiratory secretions

Can’t grow in CX dx via PCR

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14
Q

Lepromatous disease

A

weak immune system
lesions have lots of organisms
diffuse, disfiguring disease

Tx: dapsone + rifampin + clofazimine x 24 months

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15
Q

Tuberculoid disease

A

strong immune response
fewer skin lesions - hypopigmented or erythematous
-loss of sensation

tx: dapsone + rifampin x 12 mo

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16
Q

Dapsone uses

A

Hansen dz
P. jirovecii pneumonia

causes hemolysis in G6PD deficiency