HOW IS TB DIAGNOSED?

How is TB diagnosed? 

There are many tools and processes for diagnosing TB, some are cheaper and quicker to administer but are less accurate (e.g. X-rays, a skin test, and smear microscopy), others are much more accurate and sensitive but can be expensive and take long (e.g. TB Culture, which takes 4-8 weeks to diagnose). 

In South Africa we mostly use a rapid diagnostic test called GeneXpert MTB/RIF. 

GeneXpert MTB/RIF is endorsed by the World Health Organisation, and allows the rapid detection of the presence of TB, and can determine whether that TB is Rifampicin resistant. Rifampicin is a common drug used to treat TB, so if TB has a resistance to this medication, it requires a different treatment plan. GeneXpert takes a sputum sample (think mucous/phlegm!) and uses a molecular testing technique called PCR (polymerase chain reaction) to look for TB DNA in the sample. If it finds any DNA the results are positive, and all of this only take a few hours!