European Society of Mycobacteriology - Instituto Nacional de Saúde ...

PP-100
LOW COST ISOLATION OF Mycobacterium tuberculosis (MTB) FROM BLOOD
Orikiriza, Patrick
Uganda-CASE Research Collaboration, Kampala
Introduction
Routinely, identification of MTB from body fluids requires a PCR based technique which has been adopted as a gold
standard. This technique however has been unsuccessful against blood cultures which are often affected by inhibitors. In
this study, we evaluated a simple but effective way of isolating and identifying MTB in blood cultures.
Method
A total of 91 blood cultures positive for acid fast bacilli were sub-cultured onto 7H10 medium and Lowenstein Jensen
slants and incubated at 37ºc in a 5% carbon dioxide incubator. The isolates that grew on solid media were further tested
by PCR to confirm MTB. The original blood cultures were tested by diluting an aliquot of blood culture in PCR waters
and repeating the IS6110 PCR and also by Capilia for identification of MTB.
Results
The study found 15 cultures PCR positive when diluted in PCR water and 56 positive with Capilia. On the other hand,
cultures grown on the solid media before performing PCR yielded 53 PCR positives from 7H10, 44 PCR positives from
LJ and 28 did not grow on either medium.
The time it took for the cultures to turn positive on the different media was also noted
Conclusion
Identification of MTB by PCR was more efficient blood cultures were sub cultured to solid media for identification assay
Capilia tests performed directly from blood culture media gave comparable results (95%) with MTB identification by
PCR from solid growth.
There was an overall better turn around time using the 7H10 media compared to LJ medium
172 ESM 2009