41. Tuberculosis Flashcards
Which bacteria causes most TB cases?
What other ones cause TB?
What is TB?
What is a fast but not v. specific test for TB?
What are some symptoms?
Mycobacteria tuberculosis
M. bovis/africanum/microti/canetti
Respiratory bacterial disease, can affect any part of the body. slow growing - divides about once/day
Sputum smear
Drenching night sweats, lingering cough, weight loss
How is TB transmitted?
What factors does the probability that TB will be transmitted depend on?
What are the best 2 ways to stop transmission?
Spread from person to person through the air via droplet nuclei via an infectious person coughing/sneezing/speaking/singing. Need 6-8hrs exposure to acquire TB.
Infectiousness of person with TB
Environment which exposure occured
Exposure length
Virulence of tubercle bacilli
Isolate infectious people, and provide effective treatment to infectious people ASAP
How many people are a) infected and b) latently affected?
How would you diagnose latent TB?
What is the current status of TB - rising or falling?
What happens if a person has HIV and TB?
1/3 affected by over 2billion = latent
Mantoux with PPD (purified protein derivative) or gamma inteferon release assays (IGRA)
On the decline; TB is a disease of poverty.
HIV speeds up progression from latent to active TB.
How fast can TB kill an untreated person?
What is the treatment for drug sensitive TB, and the success rate?
Roughly what percentage of pts cured see eradication of drug sensitive TB?
5 years.
Isoniazid + rifampicin + pyrazinamide + ethambutol for 2 months
THEN isoniazid + rifampicin for 4 months
Daily therapy (or 3x weekly), oral. 12 months for TB meningitis.
6 month course, almost 100% cure if take for at least 6m
85%
How do we get around TB resistance to medication?
What are MDR and XDR TB?
How are these patients treated?
Give combinations of drugs in one fixed dose tablet.
Multi/extreme drug resistant TB (4/3yr survival if untreated): resistant to INH and RIF (isoniazid and rafampicin) + amikacin, kanamycin or capreomycin (injectable agents) + fluroquinolone
Combination therapy
What kind of cases of XDR TB are most seen in the UK?
How can TB be diagosed in the lab?
Pulmonary, male, 20-50, previous TB, born abroad
Microscopy of phlegm (not v. sesitive or specific but fast), fluorescent microscopes, LED microscopes. Also Gambian rats trained to sniff out TB in phlegm samples
Use culture, solid and rapid liquid systems, sensitive, can pick out MDR TB
Can also use molecular line-probe assays to look for RIF and INH resisitance: PCR amplifation of DNA from cultures and hybridisation with DNA probes
Also next gen sequencing for whole genome sequencing of bacteria.
