L15: TB+cocci Flashcards
how is TB spread?
must have active TB to spread infection
Transmission by prolonged exposure to airborne droplet nuclei→ inhaled nuclei reach alveoli
primary TB
skin test conversion in 6-8 weeks→ spontaneous healing in 6 months→ latent TB
latent TB risk of progressing to reactivated TB
5% progress by 2 years
5% progress after 2 years
90% don’t progress
But HIV patients have a 10% risk/year of progression
latent TB
No symptoms, not contagious
Macrophages ingest tubercle bacilli→ barrier shell: granuloma
Can activate to disease state if immunocompromised→ granuloma breakdown
MDR-TB
does not respond to INH or RIF
XDR-TB
does not respond to INH, RIF, fluoroquinolones
→ surgery to remove necrotic tissue
Treatment for active TB
Isolated, negative pressure inpatient hospital room
RIPE: rifampin (RIF) + isoniazid (INH) + pyrazinamide (PZA) + ethambutol (EMB)
Treatment for active TB lengths
Initially 4 meds daily x 2 months→ 56 doses→ repeat CXR, AFB smear, culture
Continuation: RIF + INH for 4 months daily or twice weekly→126/36 doses sputum culture→ +/- phase extended
completion of TB treatment is based on
total doses, not duration of treatment
Treatment of TB in HIV+
9-12 months with intermittent dosing
Treatment of TB in children
no ethambutol, extend tx
Treatment of TB if pregnant
no pyrazinamide
INH+RPT contraindicated
INH: risk of fatal hepatitis
Side effects of rifampin
orange tears, sweat, urine
skin sensitivity
Side effects of isoniazid
hepatotoxicity→ monitor LFTs
peripheral neuropathy→ give vitamin B6
→fatal hepatitis: esp in pregnant women
Side effects of pyrazinamide
Hepatotoxicity, hyperuricemia
→ contraindicated in pregnancy
Side effects of ethambutol
Optic neuritis→ test visual acuity/color vision
→ contraindicated in children
when is TB in treatment considered noninfectious
after 2 weeks+3 (-) sputum smears symptoms improve
:
Going home while still infectious
no travel, DOT, no children <5 or immunocompromised in home
Latent TB treatment options
- INH 9 months 300 mg daily or 900 mg twice weekly
Preferred therapy for pregnant women and children 2-11 years old - INH+Rifapentine (RPT)
12 weekly doses DOT
Newly preferred in 2018 for adults and children >12 years, otherwise healthy patients with HIV
Contraindicated in pregnancy - Rifampin
4 months daily→ 120 daily
If cannot tolerate INH
INH + RPT contraindication
less than 12 years old
high risk for TB
Immunocompromised: HIV, <5 years, DM, silicosis, malnutrition, substance abuse, immunosuppressants
Immigrants
IVDU
Close living quarters
TB symptoms
Fever, cough (3+ weeks), pleuritic/retrosternal chest pain
+/- weakness, weight loss, anorexia, chills, night sweats, dyspnea
TB physical exam
+/- normal
+/- posttussive crackles (classic), LAD, pleural thickening→ dullness/decreased fremitus, clubbing (severe)
TB buzzwords:
Exam:
Fever, cough
posttussive crackles
dullness/decreased fremitus
CXR:
apical/posterior upper lobes
miliary pattern
hilar LAD
preferred monotherapy for latent TB
INH
Rifampin if can’t tolerate
new guidelines: INH + RPT: no longer monotherapy but suggested bc only 12 doses
Bacille Calmette-Guerin (BCG) Vaccine
Intradermal live strain vaccine→ single dose at birth→ protects against severe consequences: meningitis, disseminated TB
Bacille Calmette-Guerin (BCG) Vaccine is recommended for
(-) TST and continual exposure
high risk MDR-TB healthcare workers
Bacille Calmette-Guerin (BCG) Vaccine is contraindicated in
immunosuppressed, children, HIV+ children
Mantoux tuberculin skin test
Forearm intradermal wheel with .1 ml purified protein derivative (PPD)
Read for induration in mm at 48-72 hours
False negatives: 2-8 weeks following exposure
> 15 mm: positive if:
Positive for everyone
> 10 mm: positive if:
Intermediate risk: recent immigrants, HIV(-) IVDU, mycobacteriology lab personnel, health care providers, high risk medical conditions, <4 years old, children and adolescents exposed to adults at high risk
> 5 mm: positive if:
High risk: HIV, recent contact, +CXR, immunosuppressed (steroids), organ transplant
2 step TB skin test (PPD)
recommended as initial test for health care workers and individuals requiring periodic retesting. Repeat test in 1-3 weeks, if (+) on 2nd test→ boosted response due to past exposure: TB infection
False positives: Bacillus Calmette-Guerin vaccine→ test with IGRA
Interferon Gamma Release Assays (IGRA): Quantiferon TB Gold and T-Spot TB:
measures immune response in blood to TB antigen: IFN-g concentration
Cannot distinguish disease from latent infection
how to collect sputum for TB testing
3 specimens 8-24 hours apart with at least 1 in the morning
acid fast smear is
supportive but nonspecific
nucleic acid amplification test is
supportive, can’t confirm TB
presumed TB, empirically treat while waiting for results of culture
both AFB and NAA positive
gold standard for TB diagnosis
culture If (+), do drug susceptibility testing
if your patient has a negative TB culture but you remain suspicious
treat and monitor response to treatment
Confirmed and suspected cases:
Report within 24 hours
identify contacts
Hallmark of TB on biopsy
necrotizing/caseating granulomas
Xpert MTB/RIF assay:
Automated NAA testing using disposable cartridges, takes 2 hours
→ identifies M tuberculosis DNA and rifampin resistance
Does not replace AFB smear or culture
CXR for TB in general
Can rule out TB, but cannot determine active vs. latent or rule out other causes
Abnormalities usually seen in apical/posterior upper lobes or superior areas of lower lobe
HIV→ atypical presentation
CT more sensitive (2nd line)
abnormalities on CXR of TB are seen in
apical/posterior upper lobes
CXR of Primary active TB:
+/ hilar LAD→ pleural effusions/infiltrates→ cavities
Miliary pattern
CXR of Latent TB:
Dense nodules/lesions +/-calcification
CXR of Reactivation of latent TB:
Cavities, infiltrates, possible adenopathy
Ranke complex
Healed primary pulmonary TB:
- Ghon lesion/Focus: calcified parenchymal granuloma (tuberculoma)
- Ipsilateral calcified hilar lymph node
Histoplasma Capsulatum
soil contaminated with bird/bat droppings→ inhalation of fungal spores→ convert to yeast at body temp
Midwestern states, Ohio and mississippi river valleys, Central and South America
Histoplasma Capsulatum incubation
Incubation: 3-17 days
Asymptomatic primary histoplasmosis
90%
asymptomatic/mild flu like→ resolve in few weeks/month
symptomatic pulmonary histoplasmosis
Fever, marked fatigue, few respiratory sx for 6 months
Mild symptoms typically self limited
Progressive disseminatedhistoplasmosis
Immunocompromised→ fever, marked fatigue, cough, dyspnea, weight loss, multi-organ involvement, fatal within 6 weeks
Chronic pulmonary histoplasmosis
Older COPD pts→ progressive lung changes→ apical cavities
Who to suspect histoplasmosis in
pneumonia with mediastinal/hilar LAD, mediastinal/hilar mass, pulmonary nodule, cavitary lung disease, pulmonary symptoms with rheumatologic arthritis/arthralgia and erythema nodosum, dysphagia with esophageal swallowing
CXR of histoplasmosis
Hilar adenopathy, patchy or nodular infiltrates in lower lobes
Asymptomatic: residual granuloma
Chronic pulmonary: apical cavities
Immunodiffusion of histoplasmosis
detects acute and chronic
complement fixation of histoplasmosis
more sensitive, less specific that ID, takes 6 weeks
antibody detection of histoplasmosis
Enzyme immunoassay (EIA) of urine/serum
culture of histoplasmosis
severe or chronic disease, takes 6 weeks
coccidioidomycosis aka
valley fever
valley fever causes
Coccidioides immitis, coccidioides posadasii
Contaminated soil→ inhalation of spores
Outbreaks: dust storms, earthquakes
Lower deserts of western hemisphere: Southwest US, Mexico, Central and South America
histoplasmosis treatment
Amphotericin B
Methylprednisolone (respiratory complications)
valley fever treatment
Typically not required
High risk/serious illness→ azoles
→ no ketoconazole due to side effects
→ teratogenic
Pregnant or severe→ amphotericin B
your otherwise healthy patient has valley fever, what’s the treatment of choice
nothing, will resolve on its own
the only azole you shouldn’t use bc of side effects
ketoconazole
pregnant+valley fever
ampho B
pregnant+histoplasmosis
gonna guess ampho B is fine since it’s okay for valley fever
valley fever follow up
every 2-4 weeks for 1 year w/o therapy, 2 years if therapy needed
valley fever incubation
1-3 weeks
% of valley fever which is asymptomatic
60%
high risk of valley fever, more likely to have disease progress
More severe presentation: immunocompromised, DM, pregnant, african, filipino
Subacute valley fever
mild respiratory symptoms, self limited, weeks to months
Protective from future disease
→ +/- progression
Primary infection valley fever presentation
CAP 7-21 days after exposure
Fever, cough, pleuritic chest pain, marked fatigue, HA, arthralgia (desert rheumatism), rash: erythema multiforme, erythema nodosum
Disseminated disease valley fever
Lungs (more pronounced lesions), bone lesions, brain
LAD, meningitis
More likely in high risk group
CXR of valley fever
+/- hilar adenopathy, patchy nodular pulmonary infiltrates, miliary infiltrates, thin wall cavities
Asymptomatic: residual granuloma
Chronic pulmonary disease:
Residual lung nodules with thin walled cavities→ disappear within 2 years
Chronic cavitary lesions with infiltrates
finding of valley fever that can mimic TB on CXR
Chronic cavitary lesions with infiltrates
if you see this buzzword look closely at the history
Enzyme immunoassay (EIA) for valley fever
more sensitive that ID
Immunodiffusion (ID) for valley fever
more specific, used following a positive EIA
Detects IgM antibodies: recent/active infection
Complement fixation (CF) for valley fever
Detects IgG antibodies→ assess disease severity
Immunodiffusion vs Complement fixation: antibodies, assesses
Immunodiffusion: IgM antibodies, recent/active infection
Complement fixation: IgG antibodies, disease severity
labs of valley fever
eosinophilia with slight leukocytosis
Valley fever skin testing
Coccidioidin or spherulin
lifelong reactivity, can’t indicate when exposed, not diagnostic
sputum culture for valley fever
difficult to obtain due to dry cough
