Mycobacterium Tuberculosis II Flashcards
What is the vaccine developed for tuberculosis?
The BCG vaccine designed from a mycobacterium bovis bacteria, it is a live attenuated vaccine but lost the important virulence determinant ESAT-6
How effective is the BCG vaccine?
It has been given to over 3 billion people but the efficacy varies from 0-80% effective and is largely ineffective against the African strains of the bacteria
How can tuberculosis be diagnosed?
It is difficult to diagnose as most people who are infected are asymptomatic
However chest x-rays, microscopic analysis of sputum, microbiological and molecular techniques can be used for diagnosis
What is the advantage of microscopic analysis to diagnose TB infection?
Though analysing the sputum you can obtain rapid results
Why is fluorescent staining more commonly used over acid fast staining in sputum analysis looking for TB?
Fluorescent staining is easier to determine if there is TB infection than acid fast staining as fluorescent staining simply requires looking for a flash of colour while acid fast staining requires checking of morphology colour etc
What are the molecular techniques which can be used to diagnose TB from sputum?
The gene expert is a machine which can provide reliable diagnosis rapidly from lung sputum
It works by placing the sputum in a cartridge which contains all the ingredients for a PCR
What is the disadvantage of the molecular tests for TB?
It requires a stable constant energy supply which is not always available in countries where it is most needed
What is the tuberculin test?
A test where purified protein derivative is injected into the skin and an inflammatory response is looked for by observation of the skin going hard and lumpy
What is the disadvantage of the tuberculin test?
It cannot determine is a person is infected with mycobacterium tuberculosis or bovis, if the infection is active or if the person has simply been exposed and people with the BCG vaccine will test positive
Why did the USA never use the BCG vaccine?
It renders the tuberculin test useless and they preferred to keep this as diagnostic tool
Why is the tuberculin test not very accurate for places that could really use it?
Individuals in Africa are more likely to be simply exposed to mycobacterium due to their environment resulting in too many false positives for the test to be useful
What are novel, cost effective ways to diagnose TB based of aromatic compounds?
Sniffer bees or rats
What is the treatment for tuberculosis?
There are two phases of treatment with an initial phase that has 3 drugs for 2 months and a continuation phase of 2 drugs for 4 months
What are the problems with tuberculosis treatment?
The drugs can be toxic with bad side effects resulting in people not taking the full course of drugs
Resistance is developing
How can tuberculosis infection hope to be controlled?
Elimination of poverty
Control of the bovine reservoirs of TB
Isolation of infectious patients
Better diagnosis and faster treatments with less side effects
