It is essential for organizations, companies and individuals to work together in the fight to end tuberculosis (TB). That is exactly what the Mozambique National Reference Laboratories (NRLs) and the University of St. Andrews in Scotland, UK have been doing to test the accuracy of a new TB treatment response assay. They have extended this collaboration to investigate the accuracy and utility of DNA Genotek’s OMNIgene®•SPUTUM reagent.
In Part One of this two-part series, we discussed the challenges around sample transport and sample quality faced by the Mozambique TB labs daily. In our concluding segment Khalide Azam, Head of the Mozambique National Tuberculosis Reference Laboratory (NTRL), Nureisha Cadir, FHI Technical Laboratory Officer, and Dr. Wilber Sabiiti (photographed here), Senior Research fellow with the Infection – Global health implementation group, University of St. Andrews, talk to us about the exciting partnership they have built together in Mozambique and how DNA Genotek’s OMNIgene•SPUTUM, a reagent that liquefies and decontaminates sputum samples, is fitting into their workflow.
What is the University of St. Andrews’ goal for its partnership with the National Reference Labs in Mozambique?
Wilber – The University of St. Andrews has been partnering with the National Institute of Health here in Mozambique to develop capacity in diagnosing TB. In this partnership, we’ve been training the laboratory personnel in molecular diagnostics, empowering them with some essential equipment they haven’t had until now, and also mentoring them on how to deal with the challenges they face. The aim of St. Andrews is to build the capacity of countries like Mozambique so they become self-sufficient.
What specifically are you looking to do in the Mozambique labs?
Wilber – Our main focus at the moment is on TB, but my group started a new department called Global Health Implementation. We are going to be looking at other infectious diseases, such as cryptococcal and bacterial meningitis, and some of our members are looking at problems such as maternal and child health issues in Malawi.
Specifically, for Mozambique, we will be developing capacity of the teams here to be able to diagnose and treat TB more effectively. For example, working with OMNIgene®•SPUTUM is going to develop the capacity of the NRLs to be able to evaluate assays or kits that may come into the country. The Mozambique team should be able to evaluate these kits before they are rolled out to the rest of the country. By evaluating OMNIgene•SPUTUM, they are not only evaluating the reagent, but also developing the capacity to investigate any new kit that becomes available on the market before the government commissions it for use in the country.
What are your expectations and hopes in using OMNIgene•SPUTUM?
Wilber – We have great expectations. One is that the OMNIgene•SPUTUM reagent is going to simplify the process of dealing with sputum. I know that here in Mozambique and in other labs in Africa, adding NAOH/NALC is not enough; they have to add beads and do some vortexing in order to break down the sputum. So our expectation is that if OMNIgene•SPUTUM can achieve liquefaction without all of that energetic beating with beads and the vortexing, this would be a great plus!
The major problem we have with culturing Mycobacterium tuberculosis (MTb) is contamination. So we expect OMNIgene•SPUTUM to solve this problem by reducing contamination levels to almost zero.
The other thing is peace of mind; the knowledge that, as long as sputum sample is mixed with OMNIgene•SPUTUM, I can leave it at room temperature for 5 days or even more and I will still get a good result. That’s great! We expect OMNIgene•SPUTUM to solve these challenges and make it very simple to use sputum as a diagnostic sample for TB.
If OMNIgene•SPUTUM meets your expectations, how will that improve the labs and diagnosis of TB in Mozambique?
Khalide – I think that if the result is good, there will be much less [culture] contamination. Our contamination rate is the problem, not just in this lab but in the other two labs that are doing culture. This will mean that more patients will be correctly diagnosed with TB. [By adding OMNIgene•SPUTUM] we can increase [maintain; sic] the viability of the bacteria and we can accurately determine whether the culture is positive or negative if we process a good sample in good time. So OMNIgene•SPUTUM will be of significant benefit in terms of diagnostic value.
Wilber – That means, in short, that it will increase the quality of results. If a sample is positive [at time of collection], it will remain positive because OMNIgene•SPUTUM will preserve the viability of the Mycobacterium tuberculosis in the sputum. When a TB patient has received treatment for the disease, the bacterial load decreases. When sputum from such a patient is treated with NaOH/NALC, it kills these bacteria, thus, when you [obtain a negative] culture you think, “oh this patient is healed”; however, the result reflects that the NaOH/NALC killed the few bacteria that were present. So with OMNIgene•SPUTUM we expect that in cases with only a few bacteria in the sample, these will remain alive and detectable by culture. The culture results will be very good and contamination issues will be reduced.
For programs, and especially for treatments, culture is now used as a treatment monitoring technique. In many cases, here in Mozambique, MGIT results are discarded due to culture contamination. Culture contamination, means that the “time to detection” MGIT result is false and cannot be used for analysis. If OMNIgene•SPUTUM solves that problem it will mean that every MGIT result will be valid and will improve the accuracy of analysis and monitoring.
The University of St. Andrews is working with the National Reference Lab in Maputo on a new treatment-monitoring assay called the mycobacterial load response assay (MBLA). Can you tell us a little bit about the assay, how this project came about and why you are working with the NRL in Maputo?
Wilber - The mycobacterial treatment-response assay is a molecular assay that detects MTb RNA. Because it detects RNA, we are able to quantify the viable bacilli that remain in the sputum when a patient is on treatment. Because GeneXpert only detects DNA, a patient who is being treated can test positive even when their culture has converted to negative [due to absence of live MTb]. By targeting RNA, we are able to quantify the bacteria that are alive and exclude those that are dead. This provides a good profile of how the patient is responding to treatment.
In terms of how this came about to work with Mozambique, the assay was first developed in 2011 in a lab in Stellenbosch, ZA. We have now expanded the evaluation to other sites to see how applicable it is in different environments. We have four sites, Mozambique being one of them. What we are testing is the the assay’s reproducibility and applicability; whether we are able to run and apply the assay in different environments. So far, it has been successful. We have had good results showing the reproducibility of the assay and that different labs are able to use it.
How you hope to improve treatment for TB?
Wilber - The value of the MBLA is its ability to provide rapid assessment of treatment response compared to culture. MGIT culture will take 7 days, even 20 days if the patient has been on treatment. With our molecular assay, we will be able to generate these results in a shorter time.
Are we going to replace culture tomorrow? No, I think it will take time before the WHO determines that we can use MBLA as the main form of TB treatment monitoring in clinics. But we think it will be easily adapted in low-resource laboratories that cannot afford culture biosafety facilities. For example, in Mozambique, only three labs in the entire country do TB culture. With MBLA, the assay does not involve or depend on multiplication of the bacteria in the sputum, and therefore poses less risk to the users. As such, this test has a greater chance of being applied in even more labs than MGIT, which is a culture method only available in very-well-equipped laboratories.
I think you are also evaluating OMNIgene•SPUTUM with MBLA assay; is that correct? How can OMNIgene•SPUTUM be used with the MBLA?
Wilber - OMNIgene•SPUTUM is good because it preserves Mycobacterium viability for downstream assays. This means that the preserved sputum will have all the viable mycobacteria we wish to detect in the assay. This implies that OMNIgene•SPUTUM will contribute to obtaining good and accurate results by the MBLA.
The other point is that culture will still be important for drug susceptibility testing because a molecular assay cannot provide those answers. Because culture is still required for drug susceptibility testing, OMNIgene•SPUTUM will remain very important as it will eliminate all the non-mycobacteria contaminants and leave only mycobacteria. So OMNIgene•SPUTUM fits very well as a reagent that supports molecular testing and culture.