TB/Histo/Cocci Flashcards
Where else besides the lungs can TB spread?
lymph nodes
kidneys
spine
brain
Etiology of TB
droplet nuclei inhaled and reach alveoli; exposure usually requires PROLONGED exposure
Progression of TB
transmission –> skin test conversion in 6-8 weeks –> primary TB –> spontaneous healing in 6 mo (latent)–> progression w/i 2 yrs, progression after 2 yrs, progression w/ concurrent HIV infection (reactivation )
Latent TB
bacteria in body w/o Sx
macrophages ingest TB bacilli creating a barrier (GRANULOMA)
unable to transmit
LTBI may activate if pt becomes immunocompromised and granulomas break down
TB disease
Sx w/i weeks or years later when immune system compromised (HIV @ high risk)
Pt CONTAGIOUS!
Risk in normal human w/ no risk factors
10% in a lifetime
Risk for TB in DM
30% in a lifetime
Risk for TB in HIV individuals
7-10% PER YEAR
Testing in TB
- TST or IGRA
- CXR: done if + for skint est; r/o other things
- Bacteriological examination: dx microbiology needed with + infection testing
- Drug Susceptibility Testing (DST)
Risk factors for RB
HIV <5 YO DM Silicosis Malnutrition Substance abuse immunosuppressive therapy Immigrant Injection drug users close living quarters
Sx of TB
- Fever
- Cough (+/- productive or hemoptysis)
- CP (pleuritic or retrosternal)
- others: weakness, weight loss, anorexia, chills, night sweats, dyspnea
- extrapulmonary TB depends on location
PE for TB
POSTTUSSIVE CRACKLES
dullness/dec fremitus
LAD
Clubbing
Dx for TB
Mantoux tuberculin skin test (TST): intradermal in forecarm - create wheal w/ 0.1 ml Purified protein derivative (PPD)
How soon do you read TST?
48-72 hours; induration measured
When will TST be positive after exposure?
2-8 weeks following exposure
Reading TST
> 5 mm: high risk group: HIV, contact w/ TB active indiv, evidence of TB on CXR, immunosuppressed, organ transplant
> 10 mm: immigrant from country w/ high rates, HIV neg injection drug users, mycobacteria lab personnel, high congregate setting, med conditions, children <4, children and adol exposed to high risk adult
> 15mm: + in anyone w/o risk factors
2 Step TB test
1st negative, repeat in 1-3 weeks
2nd postive, TB present
How does 2 step work
creates boosted response and is likely due to past exposure
What creates false + in 2 step test?
BCG (bacillus Calmette-Guerin) vaccine
IGRA
quintiferon-TB GOld & T-spot TB
What is IGRA
measures immune response in blood to TB; blood incubated w/ TB antigen and response measured (IFN-g concentration)
Limitation of IGRA
can’t distinguish between active and latent TB infection;
more expensive than TST
Benefit of IGRA
pt. does not have to return for reading
TB CXR primary active
Hilar lymphadenopathy*
may progress w/ effusions or infiltrates
cavities seen w/ progressive pulm. TV
miliary pattern!
Latent TB CXR
dense nodules or lesions w/ possible calcification
Reactivation of latent TB
cavities, infiltrates, and possible adenopathy
Where are TB abnormalities normally found
apical/posterior upper lobes*** or superior areas of lower lobes
HIV CXR
may have atypical presentation
2nd line imaging
CT- more sensitive
Ranke Complex (healed primary pulm TB)
- Ghon Lesion: calcified parenchymal granuloma (tuberuloma)
2. Ipsilateral calcified hilar lymph node
Ghon lesion
calcified parenchymal granuloma
Bacteriological exam (Sputum)
3 specimens (8-24 h apart) - @ least 1 in the morning
What do you do once you have sputum samples?
- Smear: AFB - supports dx
- Cytology: nucleic acid ampfliciation test (NAA) - supports dx
- Culture *: gold standar - confirms dx but takes 2- 6wks
Final dx of TB based on bacteriological exam
+ AFB and NAA: TB presumed, start tx immediately
culture +: TB present, do DST
Culture - and TB still suspected: treat and monitor response to tx
Bx if needed
Bx of TB
Necrotizing (caseating) granuloma***
What has necrotizing granulomas?
Bx of TB
GPA (granulomatosis w/ polyangiitis)
Xpert MTB/RIF assay
automated NAA test using disposable cartridges
What does Xpert MTB/RIB detect?
M. tuberculosis DNA and rifampin resistance
Benefits of Xpert MTB
Takes only 2 hours
minimal training needed
disadvantages for Xpert MTB
cost
does not replace AFB smear or culture
Tx for active TB
- isolation, negative pressure
- Rifampin, INH, Pyrazinamide, Ethambutol
- DOT - direct observed tx
SE of rifampin
orange secretions
skin sensitivity
SE of INH
hepatotoxicity (monitor LFT)
peripheral neuropathy
Fatal hepatitis (prego women)
How to help peripheral neuropathy associated w/ INH
give Vit B6
PZA SE
hepatotoxicity
Hyperuricemia
EMB SE
optic neuritis: test visual acuity and color vision
Criteria to not be considered infectious
- 2 weeks of tx
- 3 negative sputum smears
- sx improve
Going home while infectious
- strict follow up
- no children <5 or immunocompromised living in home
- unable to travel except to health care visits
Active TB doses
initial phase for 8 weeks: 56 doses
continuation phase for 18 weeks: 126 doses (daily) or 36 doses (2x weekly)
Latent TB tx
- ) INH: 9 mo (6 mo minimum): 300 mg daily or 900 mg 2x/week; preferred in pregnant and children 2-11
- ) INH + Rifapentine (RPT): 12 weekly doses; unable to use in pregnancy; recommended for otherwise healthy patients w/ HIV; preferred adults and children >12 YO
- ) Rifampin: 4 mo: 120 doses; given if can’t tolerate INH
Preferred Latent TB tx for pregnant women and kids 2-11
INH
Preferred Tx for adults and children >12
INH + RPT
Given to those that can’t tolerate INH
Rifampin
MDR TB does not respond to
at least INH and Rif
Causes of MDR-TB
inadequate med or dosing
premature tx interruption
spontaneous mutation
XDR-TB
responds to even less drugs, including fluoroquinolones
surgery to remove necrotic tissue important but not always available
Bacillus Calmette-Guerin (BCG) Vaccine
intradermal live vaccine
decrease risk of severe consequences due to TB disease; does not prevent primary infection of activation of LTBI; protects against meningitis and disseminated RB in children
Recommendation of BCG vaccine
single dose at birth in developing countries (WHO)
children w/ negative TST and continual exposure (CDC) - not recommend giving to HIV positive childre;
health care workers if high risk of MDR-TB
Contraindications of BCG Vaccine
immunosuppressed
pregnancy
Testing w/ BCG vaccine
blood test less likely to produce false-positive
TST not contraindicated (may have false +)
Fungal Pneumonias
Histoplasmosis
Coccidiomycosis
Others: Aspergillus, candida, cryptococcus, blastomycosis, pneumocystis jiroveci
Etiology of histoplasmosis
soil contaminated w/ bird or bat droppings (inhalation of fungal spores, body temp converts spores to yeast, proliferates in lungs and spreads to lymph or other organs)
Highest rates: midwest: OH and Mississippi River Valleys ***
HIV/AIDS or other immunocompromised indiv.
Activity associated w/ histoplasmosis
SPELUNKING construction demolition mining roofing farming gardening AC unit installation
Sx of Histoplasmosis
90% asymptomatic
mild flu-like sx
most sx resolve in weeks-a month unless severe
Asymptomatic histoplasmosis
most common in healthy
CXR: may show residual granuloma
Acute symptomatic pulmonary histoplasmosis
fever, marked fatigue, few resp. sx
sx: 1 week - 6 mo
Mild sx usually self-limited
Progressive disseminated histo
pt immunocompromised
fever, fatigue, cough, dyspnea, weigh loss
multiple organ involvement
fatal w/i 6 weeks!
Chronic pulmonary histoplasmosis
older COPD pts
progressive lung changes: apical cavities
Dx for Histo
Antibody tests: Immunodiffusion (ID) and complement fixation (CF)
Antigen detection: enzyme immunoassay (EIA)
Bx
Culture: chronic or severe disease; 6 weeks to become +
CXR
Immunodiffusion (ID) test
tests for acute and chronic infection
Complement fixation (CF)
may take up to 6 weeks
more sensitive, less specific than ID
Enzyme immunoassay (EIA)
urine** or serum testing
When to do culture for histo
chronic or severe disease
CXR in histo
hilar adenopathy
patchy or nodular infiltrates in lower lobes
Cause hilar adenopathy
Sarcoidosis
TB
Histo
Cocci
Tx for histo
acute mild-mod: no tx mod-severe: ampho or azole progressive: ampho or azole chronic: azole HIV/AIDS: ampho + azole
When to suspect histo
pneumo w/ mediastinal or hilar LAD mediastinal or hilar mass pulm nodule cavitary lung disease pulm sx w/ arthritis/arthralgia + erythema nodosum dysphagia w/ esophageal narrowing
Valley fever
coccidiomycosis
Etiology of cocci
contaminated soil;
lower deserts of wester hemisphere
outbreaks after dust storm and earthquakes
Presentation of cocci
lives/recently traveled to endemic area
excavation, construction, gardening, digging
60% asymptomatic
severe in immunocomp, prego, DM, African and filipino
Sx of cocci
asymptomatic: residual granuloma on CXR
symptomatic: mild resp sx, self-limited, weeks to months
may progress w/ chronic pulm disease or disseminated disease (high risk pts)
Primary cocci infection sx
CAP 7-21 days after exposure: fever cough, pleuritic CP, fatigue, HA, athralgia (desert rheumaticism)
rash: erythema multiform, erythema nodosum***
Disseminated cocci disease
immunocompromised
lung findings: abscess
bone lesions
lymphadenitis, meningitis
Dx of cocci
EIA
ID (more specific: used after EIA; detects IgM antibodies)
CF (detects IgG; assess disease severity)
Labs
Sputum culture
Skin test
CXR
detects disease severity
CF
detects IgM
ID
Labs for cocci
Eosinophilia w/ slight leukocytosis
Sputum culture for cocci
hard to obtain w/ dry cough
Skin test for cocci
coccidiodin or spherulin - reactivity is life not; not diagnostic
CXR for cocci
hilar adenopathy
patchy, nodular pulm infiltrates
miliary infiltrates
thin wall cavities
Chronic pulmonary disease w/ cocci CXR
residual lung nodules w/ thin walled cavities (disappear w/i 2 years)
chronic cavitary lesions w/ infiltrates (may mimic TB)
Tx for cocci
not typically required; only required in high risk/severe
sx therapy: -azole; ampho if severe or pregnant
teratogenic
azoles
f/u for cocci
every 2-4 weeks (regardless of tx provided)
sx resolve in weeks to months: continue to follow every 3-6 mo
no med: f/u for 1 year
meds: f/u annually for 2+ years for potential recurrence
think cocci
pulm complaints AND:
- erythema nodosum
- erythema multiforme
- eosinophilia