Tuberculosis - Home | Department of Pediatrics · 2020-05-12 · Clinical tuberculosis Primary TB...
Transcript of Tuberculosis - Home | Department of Pediatrics · 2020-05-12 · Clinical tuberculosis Primary TB...
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TuberculosisACTIVE VS. LATENT INFECTION & SCREENING
M ED ST UDEN T LEC T UR E SER I ES
UPDAT ED SEPT EM BER , 2019
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Bacteriology of M. TuberculosisAerobic rod
Cell wall with mycolic acid ◦ Gives the acid fast quality
◦ Weakly gram positive
Source: Infected people
Other bacteria in this genus: avum, intracellulare, leprae, bovus*
*source of BCG vaccine
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PathogenesisWe rely on T-cell mediated immunity against M. tuberculosis
Early in infection, M. tuberculosis replicates within macrophages (blocks phagolysosome fusion)
Around 3 weeks after infection Th1 response activates macrophages via INF-gamma and formation of granulomas (caseating granulomas) to contain disease
Any Th1 modulating therapy should have TB testing prior to administration
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Infection vs Active DiseaseINFECTION
In most immunocompetent hosts, generally asymptomatic
◦ Often forms fibrocalcific pulmnodule
◦ May remain dormant (latent) and await immune insult to reactivate (active)
2-4 weeks after infection, can develop (+)PPD
ACTIVE DISEASE
Clinical tuberculosis
Primary TB◦ After exposure, develop active
disease
◦ Occurs in ~5% of cases
Secondary TB◦ Infected host with prolonged latent
infection that sustains immune insult, reactivating infection
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~5%
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Primary TBOften resembles acute bacterial pneumonia
◦ Lobe consolidation, hilary adenopathy, pleural effusion
◦ May have lymphohematogenous spread
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Secondary TBUsually following latent infection and reactivation
◦ This is why we screen – to identify and treat latent TB before it becomes active disease
More commonly has apical lung disease
Symptoms concerning for TB infection◦ Weight loss, FTT
◦ Night sweats
◦ Fever
◦ Fatigue
◦ Hemoptysis, cough or chest pain for pulmonary TB
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TB Infections by TissueMeninges
Kidneys
Bones
Adrenals
Vertebrae
Intestines
Meningitis
Renal tuberculosis
Osteomyelitis
Addison’s Disease
Pott’s Disease
Intestinal TB (more common in countries where M. bovis is in unpasturized milk)
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Screening for Latent TBRisk factors
◦ Born in high risk country
◦ Immunocompromised
◦ Travel to endemic countries
◦ Housing insecurity or lives in shelter
◦ Living with someone with TB
◦ Incarceration
◦ Having contact with someone who has been exposed to TB
PPD vs IGRA (Quantiferon Gold)◦ IDSA/CDC now recommends IGRA if >/= 5yo
◦ AAP even recommends IGRA as early as 2yo if concerns for follow-up or h/o BCG vaccination
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POSITIVE Tuberculin Skin Test5mm induration if:• HIV-infected• Recent TB contact• Fibrotic changes on CXR c/w prior TB• Transplant patient• Immunosuppressed
10mm induration if:• Recent immigrant (<5yrs) from high prevalence country• IV drug user• Residents and employees of high-risk congregate setting• Mycobacteriology lab personnel• Children <4yo• Pediatric patient exposed to adult in high-risk category
15mm induration for everyone, even if no known risk factors, and including previous h/o BCG vaccination
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Treatment for Active TBRifampin
◦ Hepatotoxic, stains secretions
Isoniazid◦ May cause transaminitis, B6 deficiency
Pyrazinamide
Ethambutol◦ Optic toxicity
Streptomycin◦ Ototoxicity
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ReferencesCDC
◦ https://www.cdc.gov/tb/default.htm
Hay, W, Levin, M, Deterding, R, & Abzug, M. (2016). Current Diagnosis & Treatment: Pediatrics (23rd ed.). Lange.
Kumar, Abbas, & Aster. (2015). Robins and Cotran Pathologic Basis of Disease (9th ed.). Elsevier.
Tuberculosis in Children. Pediatrics In Review. Apr 2019, Vol 40, Iss 4. https://pedsinreview.aappublications.org/content/40/4/168