Tuberculosis Flashcards
how much of the world’s population is infected with TB?
1/4 of population (2 billion)
- latent TB –> can transition into active TB
Number of Active cases of TB?
7882
what are symptoms of TB?
- loss of weight
- tiring easily
- a cough lasting longer than 3 weeks
- fever
- low BP
who does TB disproportionately affect?
- Immunocompromised
- Malnourished
- Homeless
- Overcrowded or poor living conditions
- Advance, untreated HIV
- healthcare workers
what is TB caused by?
mycobacterium tuberculosis (M. Tb)
- aerobic, rod shaped bacilli
-MC cause
-8 other bacteria can cause tb
How is mycobacterium tuberculosis transmitted?
droplet nuclei
- spreads easily
- transported to alveoli
- when patient coughs, sneezes, shouts, sings
Where does m.TB. Multiply in?
In the alveoli
what is a primary TB infection?
TB that occurs when bacteria are inhaled and the inflammatory response is activated
what is latent TB?
(90% of patients)
Bacterium are contained by granulomas
- no symptoms
- not infectious
- cannot spread disease
what is active TB?
(10% of patients)
- TB that progresses and is infectious
- mycobacterium tuberculosis spreads to other organs, infects more
- immune system cannot contain M.TB
latent TB can transition into?
active TB
What is the first step in M.TB transmission
- droplet nuclei containing M. tb are inhaled and enter the lungs, travel to the alveoli
What is the second step of M.Tb transmission
- droplet nuclei gets past pulmonary defenses
- M. tb multiply in the alveoli
What creates Latent TB (90%)
macrophages ingest and surround the TB bacilli
*creates a barrier (granulomas) keeps bacilli contained
*need drug tx
What creates active TB or (reactivation of secondary TB)
Happens when the immune system cannot keep up with the TB bacilli and they escape macrophage activity (will multiply)
*extrapulmonary TB
Where does the M.TB bacilli spread during active TB
Blood stream and lymphatics
what type of room should a patient with TB be placed in?
negative pressure room
what determines the probability of transmission of TB?
- immunocompetency of individual exposed
- infectiousness of person disseminating TB (environmental factors, proximity, etc.)
*number of TB bacilli the patient expels
T/F. patients with latent TB are infectious and can spread TB to others.
F
can you tell if a patient has latent or active TB when looking at a chest x-ray?
No
can M. tb be sampled in latent TB?
No
if a patient has latent TB and are not treated, what is the chance they will develop active TB?
5 to 6%
T/F. you cannot predict who will develop to active TB (Or re-activation)
T
what are risk factors for developing active TB?
- untreated HIV infection
- close contact with infectious TB case
- renal failure
- smoking
- overweight
what happens to cause active TB?
granulomas break down and bacilli escape, multiply, spread
Are people with active TB infectious?
Yes can spread to others
which patients normally have a positive TB skin test?
latent TB, active TB, and those who have the TB vaccine
when are sputum smears and cultures positive for TB?
Active
when is TB notified to the public health department?
latent or active TB
what are increased risk patient populations for TB?
- pediatric
- foreign born patients
- minorities
- lower socioeconomic status
- immunocompromised
-health care workers
if a child has TB, what does that mean?
there is an active spread somewhere
if an immigrant has TB, what does that mean?
they probably got it from their home country
what are the symptoms of active TB?
- Constitutional symptoms
- Malaise, Fatigue
- Anorexia
- Weight loss
- Fever
- Night sweats
- Chronic cough** (dry and then productive, purulent to blood streaked later on)
- Chest pain (pleuritic)
what are the signs of active TB?
- lymphadenopathy
- possible abdominal, bone, or joint involvement
- unremarkable pulmonary exam (may have rales)
how is TB screened for?
TB skin test (PPD, Mantoux test)
what does a positive skin or blood test show?
that a person has been infected with TB bacteria but DOES NOT differentiate whether the person has Latent or Active TB
what is the Mantoux test?
intradermal injection of 0.1 mL PPD of volar surface of the arm
when should the Mantoux test be delayed?
after live vaccines
a patient with an induration of 5 mm may be?
immunocompromised
- HIV
- organ transplant
- recent contact with TB
-fibrotic changes on X-ray
a patient with an induration of 10 mm may be?
- IV drug users
- healthcare employee
- comorbid conditions
- children«5
a patient with an induration of 15 mm may be?
persons with no risk factors for TB
what is a positive reaction of a Mantoux test?
a raise of skin (induration) 48-72 hours later
- DO NOT measure redness
- document in mm
if there is a negative PPD, what can be done?
a two-step PPD
* - may take weeks for the person to develop a reaction
what can cause a false negative of PPD?
- Anergy (false immune response)
- Viral, bacterial, fungal co-infection
•Recent TB infection
•Errors in skin test administration
what can cause a false positive of a PPD?
- Nontuberculous mycobacteria
- BCG vaccination (for TB)
- Errors in skin test administration
what is the blood screening test for TB?
Interferon-gamma release assay
-Also called QuantiFERON or T-SPOT test
what is an advantage of quanitferon test?
will not give a false positive in patients who have received a prior BCG vaccination
can a quantiferon test determine if it is latent or active TB?
No
what is the expected result of a chest x-ray for a patient with TB?
upper lobe/apical, cavitary disease (O2 level higher in upper lobes)
how do chest x-rays appear in elderly patients with TB?
lower lobe infiltrates, +/- effusion
who is a miliary pattern seen in?
immunocompromised patients
-diffuse small nodular densities (hematologic or lymphatic dissemination)
a resolution of an active TB case can cause?
- dense nodules calcification, upper lobe
- Ghon complex: calcified primary focus
- Ranke complex: calcified primary focus and calcified hilar lymph node
what gives you an idea that a patient might have TB?
acid-fast microscopy
*does not confirm diagnosis
*shows presence of ATB
what is needed to make a definitive diagnosis of TB? (Only active)
M tb culture or DNA/RNA amplification techniques
*NAAT-TB
what is the mainstay of diagnosis for TB?
exam for acid-fast bacilli and TB culture
*TB culture done on all initial samples to confirm diagnosis
*Positive culture for M tb confirms diagnosis
is a positive culture for TB always necessary to begin treatment for TB?
no, start treatment asap
- may take weeks to have a result
what are complications of TB?
- mortality
- Musculoskeletal: vertebral (Pott’s disease), joint disease
- Lymph nodes (scrofula)
- Neurologic: meningitis
- Cardiovascular: pericarditis
- GI: peritonitis
- GU: kidney, adrenal
- Derm: cutaneous
what is DOT?
directly observed therapy
- healthcare worker watches patient consume each dose
- preferred management strategy for patients who are on 2-3 times a week medication or it patient cannot stick to regimen on own
what is the treatment for TB?
- infectious disease consult/referral
- drugs: Isoniazid, Rifampin, Pyrazinamide, Ethambutol, Maybe: Streptomycin
what must not be consumed during TB treatment?
NO alcohol
what must be monitored during treatment of TB? (General)
- lab testing, CBC with platelets, serum bilirubin, hepatic enzymes, urea nitrogen, creatinine
what must be monitored during treatment of TB? (Visual)
Ethambutol
what must be monitored during treatment of TB? (Serum acid)
Pyrazinamide
what must be monitored during treatment of TB? (Audiometry)
Streptomycin
what are common adverse reactions with treatment of TB with INH?
- peripheral neuropathy (give Vit B6)
- fetal hepatitis
- elevated liver enzymes (AST and ALT)
- interacts with phenytoin, disulfiram
what are common adverse reactions with treatment of TB with RIF?
- hepatitis, fever, rash, flu-like illness, GI upset, bleeding issues, kidney dysfunction
- orange body secretions/urine
when is a patient considered no longer infectious with active TB?
- 3 consecutive negative sputum smears
- Symptoms have improved, and
- Patient is adherent to an adequate treatment regimen for at least 2 weeks
if the treatment for TB is interrupted (common), what should you do?
restart or continue therapy
what is the prognosis of TB?
- immunocompetent often cured
what is the TB vaccine?
Bacillus Calmette-Guérin (BCG)
-Mycobacterium bovis attenuated strain
when is the TB vaccine CI?
pregnant women and immunocompromised patients
what is a SE of the TB vaccine?
a bluish red pustule at site of injection, which in turn could progress to an ulceration
- Can last for up to three months
Is nosocomial tb common in the us
No
