Abstract
The diagnostic delay still remains one of the important factors contributing to an increase in TB
disease severity and mortality.
The Xpert® MTB/RIF (Cepheid, Sunnyvale, CA) assay is a rapid molecular diagnostic test being
introduced at an alarming pace into many countries across the globe to detect TB and rifampicin
(RIF) resistant TB. This new diagnostic tool has positively contributed to the 42% increase of
new diagnosed TB cases from 2011 to 2012.
An integral tool in determining valid laboratory results for effective TB treatment depends on
result accuracy, all of which is monitored by an External Quality Assessment (EQA) programme.
TB EQA is vital in all Quality Management systems for medical laboratories to comply with ISO
15189 standard (International organization for standardization).
The manufacture of Mycobacterium tuberculosis in bulk culture in preparation for EQA material
is challenging due to the highly infectious, air-borne nature of the mycobacterium, and therefore
the preparation of quality material that sustains an effective EQA programme was investigated
in this study. Many factors were considered prior to the preparation of bulk culture, most
importantly the safety of EQA material during transportation and testing; as well as compatibility
to the characteristics of the Xpert® MTB/RIF assay, and therefore the format of the most suitable
EQA material.
It was determined that the manufacture of TB in a single cell format could then be more easily
quantified by flow cytometry, inactivated and then prepared in liquid format as the most suitable
for performing EQA on the Xpert MTB/RIF, however, the dried culture spot format was a more
easily transportable product for EQA and therefore more sustainable as a long term EQA
programme.
M.Tech. (Biomedical Technology)