From the study: The intriguing observation th
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Posted On: 12/06/2017 10:54:08 AM
Re: elsiesyouraunt #4117
From the study:
The intriguing observation that Mtb-specific RD9 DNA sequences could be detected in almost all patients with the ddPCR assay raises fundamental questions as to what these DNA sequences represent. Future work is aimed at resolving whether the Mtb DNA signal was from DNA incorporated in viable or non-viable Mtb cells or, possibly, cell-free DNA. Recent studies have identified differentially culturable Mtb in sputum samples.24 Further studies exploring the increased magnitude of PCR signal compared with CFU could explore whether differentially culturable organisms such as those reported to occur in sputum20, or produced in vitro by rifampicin treatment of starved cultures of Mtb, occur in patient-generated bio-aerosols.
The fact that PCR detects active and inactive cells is a significant distinction between the NNLX technology and the PCR being used here--as well as the quality and timing of the NNLX tech which is better. Along with that, when you read the study you can see that the described test requires an extensive and pretty clunky "clean room" that has to be used for this to have a chance to work, a patient sitting and breathing in that "chamber" for an hour while bacteria (dead and alive) are being collected for another process of review, and presumably an extensive cleansing/disinfecting of the "Chamber" to prepare it for the next person. This describes a slow, difficult, labor intensive and only partially reliable process that is for a carefully managed research laboratory setup rather than high volume situations characteristic of actual field treatment in African countries. Gates has a bias in favor of machinery but they are still buying and using the NNLX tech that is advanced and better than anything else on a range of critical parameters.
The intriguing observation that Mtb-specific RD9 DNA sequences could be detected in almost all patients with the ddPCR assay raises fundamental questions as to what these DNA sequences represent. Future work is aimed at resolving whether the Mtb DNA signal was from DNA incorporated in viable or non-viable Mtb cells or, possibly, cell-free DNA. Recent studies have identified differentially culturable Mtb in sputum samples.24 Further studies exploring the increased magnitude of PCR signal compared with CFU could explore whether differentially culturable organisms such as those reported to occur in sputum20, or produced in vitro by rifampicin treatment of starved cultures of Mtb, occur in patient-generated bio-aerosols.
The fact that PCR detects active and inactive cells is a significant distinction between the NNLX technology and the PCR being used here--as well as the quality and timing of the NNLX tech which is better. Along with that, when you read the study you can see that the described test requires an extensive and pretty clunky "clean room" that has to be used for this to have a chance to work, a patient sitting and breathing in that "chamber" for an hour while bacteria (dead and alive) are being collected for another process of review, and presumably an extensive cleansing/disinfecting of the "Chamber" to prepare it for the next person. This describes a slow, difficult, labor intensive and only partially reliable process that is for a carefully managed research laboratory setup rather than high volume situations characteristic of actual field treatment in African countries. Gates has a bias in favor of machinery but they are still buying and using the NNLX tech that is advanced and better than anything else on a range of critical parameters.
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