TB/Histo/Cocci Flashcards
what organism causes TB
Mycobacterium tuberculosis
how is TB transmitted
- airborne droplet nuclei
- usually requires prolonged exposure
- pt must have active TB to spread infection
when will a skin test show up positive after exposure to TB
6-8 weeks
of people who get infected with TB, what percentage will have active disease (primary)
5%
of people who get infected with TB, what percentage will have active disease (secondary) after latent TB
5%
of people who get infected with TB, what percentage will become latent infections
95%
describe latent TB infection
- TB present in body without symptoms
- TB live in granuloma
- unable to transmit infection to others
- Latent TB may activate to disease if pt becomes immunocompromised and granulomas break down
what percentage of patients infected with TB get active TB
- 10%, 5% intially, and 5% develop from latent
list steps of medical evaluation of TB
- medical history
- physical exam
- TB infection testing
- CXR
- bacteriological examination
risk factors for TB
- immunocompromised
- HIV
- immigrants from areas of high TB prevalence
- IV drug users
- close living quarters
- nursing homes, correctional facilities, hospitals
clinical presentation
- fever
- cough
- 3+ weeks
- +/- hemoptysis
- +/- productive
- 3+ weeks
- CP
- weakness, weight loss, chills, night sweats
- PE: posttussive rales
TB
what are possible complications from TB
- pneumothorax
- bronchiectasis
- malignancy
- pulmonary aspergillosis
- septic shock
Describe TB skin testing
- Mantoux tuberculin skin test (TST)
- given in forearm intradermal
- read in 48-72 hours
- measure induration, not erythema
For what groups is a reaction size of > or = 5 mm considered positive TB skin test
- HIV +
- recent contacts of person with active TB
- persons with evidence of TB on CXR
- immunosuppressed
- organ transplant
For what groups is a reaction size of > or = 10 mm considered positive TB skin test
- recent immagrants from areas with high rate of TB
- IV drug users
- mycobacteriology lab personnel
- residents.employees of high risk congregate setting
- children < 4 yo
- infants, children, adolescents exposed to adults at high risk
For what groups is a reaction size of > or = 15 mm considered positive TB skin test
positive in anyone even without risk factors for TB
describe the 2 step skin test for TB. When it is recommended
- recommended as initial test for health care workers and individuals requiring periodic retesting
- 1st negative, repeat in 1-3 weeks
- 2nd positive, TB infection present (creates boosted response)
- ** BCG vaccine may create false positive
what is the interferon gamma release assay: Quantiferon TB Gold
- measure immune response in blood to TB
- may be used in place of TST if patient has recieved BCG vaccination
- unable to differentiate between TB disease and latent TB infection
what initial presentation may be seen on CXR when you suspect a patient has TB
- normal or hilar lymphadenopathy
What is typical on CXR of a person with latent TB
- typically normal
- can see dense nodules or lesions with possible calcification
TB usually settles in what part of lung
- apical/posterior upper lobes
If patient has positive TB skin test, and suspicious CXR, what is the third step? describe it
- bacteriological exam: sputum collection
- 3 specimens (8-24 h apart)
- at least 1 in the morning
What three things are you looking for in sputum collection for TB patient
- smear: acid fast bacilli
- cytology: nucleic acid ampification test (NAA)
- culture: gold standard **confirms diagnosis but may take weeks
how is TB diagnosed
- if both smear (showing acid fast bacteria) and nucleic acid amplification test are positive, TB disease is presumed and treatment begins
- DO NOT delay treatment waiting for culture
Treatment of active TB
- isolated negative pressure inpatient hospital room
- drugs (RIPE)
- Isoniazid
- Rifampin
- Pyrazinamide
- Ethambutol
- **DOT: direct observed treatment
side effects of isoniazid
- hepatotoxicity; monitor LFT
- peripheral neuropathy; patients given Vitamin B6
side effects of rifampin
red-orange tears, sweat, urine
side effects of pyrazinamide
- hepatotoxicity
- hyperuricemia
side effects of ethambutol
optic neuritis: test visual acuity and color vision
length of treatment for TB
- initial phase: 4 meds daily x 8 weeks, then
- continuation phase:
- RIF and INH daily x 18 weeks or
- INH and RIF twice weekly for 18 weeks
length of treatment for TB in HIV +
treatment is extended 9-12+ months
treatment for TB in pregnant women
Pyrazinamide not given
treatment for TB in infants/children
ethambutol not given and may extend treatment
When is a person on TB medication not considered infectious
- 2 weeks of treatment regimen
- 3 negative sputum smears
- symptoms improve
treatment for latent TB
- 9 month daily regimen of isoniazid
- monitor LFT
- give with vit B6
What classifies TB as MDR-TB
does not respond to at least INH and RIF
What classifies TB as XDR-TB
does not respond to INH, RIF or fluoroquinolones
is there a test available to quickly determine if TB is drug resistant
Xpert MTB/RIF test
- rapid TB test: result in 2 hours
Describe the bacille calmette guerin vaccine. type and purpose
- intradermal live strain vacccine
- purpose: decrease risk of severe consequences due to TB disease
- does not prevent primary infection or activation of LTBI
CDC recommendations for who should get BCG vaccine
- children with negative TST and continual exposure
- does not recommend HIV positive children
- health care workers if high risk of MDR-TB
CDC recommendations for who should NOT get BCG vaccine
- immunosuppressed
- pregnancy
is TST or blood test contraindicated if person has recieved BCG vaccine
No, blood test will likely produce false positive
where is histoplasmosis normally found
- soil contaminated with bird or bat droppings
- midwestern states: ohio and mississippe river valleys
how is histoplasmosis transmitted
- inhalation of fungal spores from contaminated soil
- body temp converts spores to yeast
- yeast proliferates in lungs and spreads to lymphatics -> other organs
histoplasmosis is most commonly found in what patient populations
- HIV/AIDS
- weakened immune systems
clinical presentation
- recent activity: spelunking, construction, mining, farming, gardening
- mild flu like symtpoms
histoplasmosis
define asymptomatic primary histoplasmosis
- most common in otherwise healthy people
- CXR may show residual granuloma
define acute symptomatic pulmonary histoplasmosis
- fever and marked fatigue, few respiratory symptoms
- symptoms 1 week-6 months
- typically self limitied
define progressive disseminated histoplasmosis
- pt typically immunocompromised
- fever, marked fatigue, cough, dyspnea, weight loss
- mutliple organ involvement
- fatal within 6 weeks
older COPD patients who get histoplasmosis, usually present with
- chronic pulmonary histoplasmosis
- see progressive lung changes
- apical cavities
how is histoplasmosis diagnosed
- **antigen detection: enzyme immunoassay (EIA test) : recommended to get this first
- typically urine or serum testing
- antibody tests
- immunodiffusion (ID) test
- tests for acute and chronic infection
- complement fixation
- immunodiffusion (ID) test
-
culture: gold standard
- definitive diagnosis; may take 6 weeks
When does a patient start to get treatment for histoplasmosis? What is the treatment?
- acute pulmonary: mild-moderate > 4 weeks
- treatment: itraconazole x 6-12 weeks
What CXR findings are consistent with histoplasmosis
- hilar adenopathy
- patchy or nodular infiltrates in lower lobes
If patient /o pulmonary sx with rheumatologic arthritis and erythema nodosum, what should you be concerned about
fungal infection
How is Coccidioidomycosis (valley fever) transmitted
- inhalation of spores from contaminated soil
- endemic to lower desserts of western hemisphere
- outbreaks occur following dust storms
high risk groups who tend to have a more severe presentation of Coccidioidomycosis (valley fever)
- immunocompromised
- pregnant
- DM
- African or Filipino ethnicity
What percentage of people who are exposed to histoplasmosis are symptomatic
90% are asymptomatic or have mild flu-like symptoms
what percentage of individuals exposed to Coccidioidomycosis (valley fever) are symptomatic
- 60% are asymptomatic
- 40% symptomatic (<1/2 seek medical care)
if a person has asymptomatic Coccidioidomycosis (valley fever), what could still be present on CXR
residual granuloma
What are typical symptoms of Coccidioidomycosis (valley fever) in previously healthy people
- mild respiratory sx; self limited, lasting weeks-months
- may progress to chronic pulmonary or disseminated disease in high risk group
clinical presentation
- CAP 7-12 days following exposure
- fever, cough, pleuritic CP
- marked fatigue, HA, arthralgia
- rash: erythema multiform, erythema nodosum
primary infection Coccidioidomycosis (valley fever)
if Coccidioidomycosis (valley fever) disseminates, where does it usually go
- Lungs, Bones, Brain
- more pronounced lung findinds: abscess
- bone lesions
- lymphadenitis, meningitis
how is Coccidioidomycosis (valley fever) diagnosed
- immunodiffusion (ID) test
- detects IgM
- enzyme immunoassay (EIA)
- complement fixation
- detect IgG
what immune cell type is prominant in Coccidioidomycosis (valley fever) infection
eosinophilia
what CXR findings are consistent with Coccidioidomycosis (valley fever)
- vary
- hilar adenopathy
- patchy, nodular pulm infiltrates
- miliar infiltrates
- thin wall cavities
- chronic pulm dz: residual lung nodules thin walled cavities or chronic cavitary lesions with infiltrates
treatment for Coccidioidomycosis (valley fever)
- typically not required, if appear healthy, do NOT need treatment
- tx recommended for high risk or severe illness
-
fluconazole and itraconazole
- **check LFTs
-
fluconazole and itraconazole
treatment of Coccidioidomycosis (valley fever) in pregnant females
amphotericin B (azoles are teratogenic)
what is highest on your differential with these:
- pulmonary complaints
- ertyhema nodosum
- erythema multiforme
- eosinophilia
Coccidioidomycosis (valley fever)
