Over the past 4 years the Center for Tuberculosis (CTB) in Johannesburg has played an important role in assisting SMMS in the development and operation of the TBDx™ hardware and software technology. Not only has the lab provided the staff necessary to stain slides, acquire digital images and provide advice on tuberculosis detection, but also it has been the primary location for our technology evaluations.
This support is especially impressive as the lab was deploying molecular diagnostics (Cepheid’s GeneXpert) simultaneously. The introduction of this technology reflected the commitment made by the Ministry of Health to effectively respond to the growth of drug resistant TB within the country. Today, South Africa accounts for 50% of worldwide use of the GeneXpert molecular cartridges.
Last month our Director of Engineering, Tosh Sondh, traveled to South Africa at the request of the CTB. The CTB laboratory in Johannesburg is a high-volume, quality assurance lab processing thousands of slides on a weekly basis. Due to the absence of a veteran microscopist TBDx™ became a ready-made technology solution that could assist in slide processing.
An advantage of TBDx™ is its high-volume configuration, which uses the optional 200-slide robotic slide loader. This feature allows CTB to productively address the daily high volume slide requirements. Tosh trained several CTB microscopists and technicians in the operation of TBDx™. It also afforded an opportunity to update the CTB system to the latest version of the software.
The use of the TBDx™ unit presents an opportunity to further the potential for TBDx™ to screen suspected TB cases in a “triage” capacity. The recent evaluation presented evidence that the predictive values of TBDx™ could play a beneficial role in removing negative cases from consideration, and targeting most likely positive cases for referral to molecular testing. The use of the unit will permit additional evaluation of this potential. The realization for computer vision image analysis to automate sputum microscopy and deliver a faster, accurate diagnosis has never been more close. Layering this technology with molecular diagnostics, reducing the overall cost impact to assess drug resistance has never been more clear.
Other Opportunities Revealed During the Lab Visit
Following the software updates and staff training, new activities were pursued that will enhance the technology.
- Two new Wescor auto-staining units have been installed in CTB and these will be used in tandem with TBDx™. This technology shortens the staining cycle and improves workflow to a point where more slides can be analyzed faster. Also, a slide stained with such technology will produce a more consistent stain, something that improves the ability of the TBDx™ software to detect objects.
- The existing detection software has been trained from images acquired using a mercury vapor light source. More labs are moving towards using LED lighting because the lights last longer and are less expensive. During our visit an LED light source, provided complimentary by the Italian company Fraen, was fitted to the microscope and digital images were acquired to evaluate how the detection software performed under this light source. Again, though the bacteria counts may have been slightly different, the case determinations remained the same. Additional research and investigation is required, the evidence shows that an LED light source can be successfully adapted to the TBDx™ platform.
The effort in South Africa continues to present opportunities for the company. The potential to bring computer-vision to the lab is both real and appropriate. The less expensive LED light source not only can bring a more affordable hardware solution to the laboratory, but also the auto-staining solution can bring a more consistent, better performing slide solution to diagnostic performance.