Tuberculosis Flashcards
What is TB?
Bacterial infection caused by Mycobacterium tuberculosis complex, infecting one in three people globally (5-15% develop into active TB).
Who is at risk?
*born in high prevalence area
*children <5 years old
*close contact with person with ACTIVE TB
*immunosuppressed i.e on immuno drugs
What is the pathogenesis of TB?
*airborne bacterial infection
*affect any part of body-mainly lungs
*transmitted via coughs,sneezes, singing
*inhalation of droplet through mouth/nasal cavity
How is TB transmitted?
Inhalation of an airborne droplet produced by an active TB patient coughing, sneezing, singing etc.
What are the three possible outcomes from inhaling TB droplets which have deposited in the lungs?
*immediate clearance via immune system
*primary active disease
*latent disease
What are the differences between latent and active TB?
*latent tb involves persistent immune response to mycobacterium tuberculosis antigens with no evidence of activity i.e no symptoms or progression
*active tb shows evidence of symptomatic or progressive disease of lungs and/or other organs
*latent tb patients not infective
*active tb patients infective
*90% of patients have latent tb
*10% of patients have active tb
What are factors for poor prognosis (life after disease)?
*multi-drug resistance
*increasing age
*HIV co-infection
*more extensive disease state
What are symptoms of active TB?
MAIN
*cough >3 weeks
*chest pain
*coughing up blood or sputum
OTHERS
*fatigue
*weight loss
*chills/fever
*children present with NON SPECIFIC symptoms
NB- 40% of patients can have extra pulmonary symptoms
What are the three classes of Tb?
*primary disease- progression of asymptomatic/few symptoms to active disease
*post primary disease- following treatment, disease can return if not all bacteria killed (few people)
*latent tb infection- thousands fewer tb bacteria than in active tb
What is extra-pulmonary tb?
Tb involving organs of the body other than the lungs
How is active pulmonary tb diagnosed?
*chest x-ray- shows infiltration of upper lobes
*three sputum sample’s microbiology tested
How is extra-pulmonary tb diagnosed?
*chest x-ray
*spontaneous sputum sample for microbiological testing
*ct scan
*ultrasound of lymph nodes/kidneys
*ecg of heart
Who should be screened for tb?
*those in close contact with patient with active tb
*immunocompromised
*people entering uk from high tb-prevelance
*new NHS employees working with patients
How is latent tb tested for?
*Mantoux test- small amount of PPD tuberculin injected into skin. Positive= small red hard bump within 2-3 days (strong skin reaction suggests active tb so needs further testing)
* interferon gamma release assay test (blood test)
What causes resistance in tb?
*poor mediation compliance
*unsuitable treatment
* lack of availability of high quality drugs
*interrupted treatment
