Why GeneXpert Matters to PIH and Global Health
How this machine has become a critical tool in providing timely diagnoses to patients
Posted on Sept 14, 2023
The GeneXpert is a machine that tests clinical samples to quickly identify infectious diseases, such as tuberculosis (TB). As TB remains the world’s deadliest infectious disease, treatment and support rely first and foremost on diagnosis. This machine has become critical to patient care at eight Partners In Health (PIH) care delivery sites, as it allows clinicians to receive complete and accurate diagnoses quickly, ultimately helping treat patients effectively and stop the spread of disease.
To learn more about GeneXpert, we spoke to Megan Striplin, laboratory services program manager for PIH; Nadeige Hilaire, laboratory coordinator for Zanmi Lasante, as PIH is known in Haiti; and Mokenyakenya Matoko, laboratory lead for PIH Lesotho. Below, edited and condensed, are their responses to questions about the technology, why the machine is vital to patients, and the challenges we face in the global diagnosis and treatment of TB:
What is the GeneXpert?
The GeneXpert is a closed-system polymerase chain reaction (PCR) machine that allows you to perform automated, cartridge-based PCR–the gold standard for many diagnostic lab tests. With GeneXpert, a PCR test can be performed within hours, by inserting a disease-specific cartridge into the machine that will detect and amplify specific sequences of genetic material (DNA or RNA), confirming the absence or presence of that disease of interest from the sample. Traditional PCR testing requires a molecular biology lab with skilled technicians and a highly controlled environment. Utilizing the GeneXpert machine allows you to bypass those needs and provides a more “point-of-care” test.
Each cartridge is used for a single PCR test for a specific oncology marker or infectious disease, such as COVID-19, HIV, and more. The cartridges are single-use, self-contained, and consist of all necessary reagents for PCR testing.
If we want to make an analogy using a pre-prepared meal, the GeneXpert cartridge is the TV dinner and the GeneXpert machine is the microwave–the ONLY machine that can heat it. The beauty of the cartridge, or TV dinner, is that all ingredients are included, pre-measured, and prepared–you do not need a cutting board or chef knife, and it does not require a trip to the market for the individual ingredients. The level of technical “culinary” skill level is minimized, and finish time is significantly shortened.
How long has PIH been using GeneXpert technology?
For over a decade. PIH Lesotho first started using the GeneXpert around 2012 for TB testing. They were the first facility in the country to have a GeneXpert machine.
How many PIH care delivery sites are using the GeneXpert machines?
We currently have GeneXpert machines at eight PIH-supported facilities–in Haiti, Peru, Lesotho, Malawi, Rwanda, Liberia, Sierra Leone, and Kazakhstan.
How many tests are we running a year through GeneXpert machines? What are we primarily testing for?
We run thousands of tests per year using the GeneXpert. In Haiti, we’re running about 8,500 tests per year, and in Lesotho, around 5,000-6,000 tests per year—to give a couple of examples. We test primarily for TB, but also HIV viral load, HIV early infant diagnosis, and Hepatitis B viral load.
Why are these machines important to our work, for both PIH clinicians and patients?
From a clinical perspective, GeneXpert provides useful information such as HIV and Hepatitis B viral load and confirmation of the presence of infectious disease. For TB specifically, the GeneXpert cartridge provides drug susceptibility testing which informs what treatment will and won’t be effective, which also helps classify if a patient has drug-sensitive TB or multidrug-resistant TB (MDR-TB).
These machines also do not require highly skilled lab staff, and cartridges can be stored at room temperature, which is huge for our care delivery sites. And once you have one machine, you can perform a variety of different tests, so long as you can afford the cartridges.
For our patients, the turnaround time to receive results is drastically reduced to hours, enabling patients to receive their results within the same visit–allowing for timely treatment and preventing the spread of disease.
What would happen if we didn’t have the GeneXpert machines?
Mainly, we miss out on the opportunity for quick diagnosis and treatment for TB patients. Overall, our diagnostic capacity would be significantly crippled, in particular for TB, where the alternatives are smear microscopy (which is not very accurate) and/or sending out sputum samples to the reference laboratory for culture, which can take a month, or longer, to receive the results.
Without the GeneXpert machine, a process that only takes hours at PIH-supported laboratories would take weeks or months at national reference TB labs.
What impact would it have on our care delivery sites if cartridge prices were lowered?
A major challenge we face with these machines is cost, including the recurring cost of the cartridges and the machines themselves. If the price per cartridge was lowered, we could increase access significantly. We’re currently limited on the number of tests we can perform simply due to budget.
Tuberculosis (TB) is preventable and treatable. Despite this, 1.6 million people died from the infectious disease in 2021—a majority of whom live in low- and middle-income countries. We spoke to three researchers involved with the endTB clinical trial in Lesotho; read their responses to questions exploring the challenges of this clinical trial, preliminary results, and what this means for global TB care.
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