EDCTP FUNDED STUDIES

According to historical data, tuberculous meningitis (TBM) is the most common type of bacterial meningitis in the Western Cape province of South Africa. It is the most severe manifestation of TB with high morbidity and mortality, despite adequate anti-TB therapy. This is mainly the result of delayed diagnosis and initiation of appropriate therapy. Despite ongoing research, early, cost-effective diagnostic tools are lacking. Demonstration of acid-fast bacilli and/or culture of Mycobacterium tuberculosis (Mtb) from cerebrospinal fluid (CSF) represents the gold standard method for diagnosing TBM. Unfortunately, the sensitivity of both these tests is low. The diagnosis of TBM is therefore based on a combination of clinical, laboratory and radiological findings. 

In a recently patented and published study conducted by our research group, we investigated the usefulness of some of the host markers that we identified in our previous studies as diagnostic candidates for TBM. A three-marker CSF biosignature comprising of IL-13, VEGF and cathelicidin LL-37, diagnosed TBM with a sensitivity of 52%, specificity of 95%, with positive and negative predictive values of 91% and 66% respectively.  There is a need to validate this signature in a new cohort of children with suspected TBM, and ascertain whether the signature can be further optimised using additional biomarkers. There has also recently been several reports on the use of host transcriptomic biomarkers as TB diagnostic candidates. However, none of these studies have been conducted specifically in children with TBM and it is not known, whether simple blood RNA signatures such as the ones already identified for pulmonary TB might be useful in this disease. 

The overall aim of the current study is therefore to assess the utility of ex vivo blood and CSF based host cytokine biomarkers and RNA transcripts as diagnostic tools for TBM. We are specifically validating the diagnostic accuracy of our previously established 3-marker TBM CSF biosignature as well as evaluating other new host markers which have shown potential in adult studies but which have not been investigated in children yet. This will be followed by the development of prototype rapid tests, which could be further refined for the easier and earlier diagnosis of TBM in children.

Status update:

As of the 31 July 2025, all work proposed under this project was completed. Work on the project was carried out under 5 Work Packages (WPs), that covered the refinement of host inflammatory protein biosignatures on cerebrospinal fluid (CSF) and serum samples, for the diagnosis of childhood TBM, the development of prototype POC devices, evaluation of the devices in specimens collected from newly recruited study participants, and the training of students and postdoctoral fellows.

In the work that was carried out through the 5 work packages, we validated proteins that are detectable in both cerebrospinal fluid and blood  as diagnostic biomarkers for childhood TBM, and further optimised the previously established biomarker signatures, resulting in multiple highly promising diagnostic biomarker combinations from both bodily fluids. The expanded list of biomarkers that were also evaluated in the project led to the identification of panels of biomarkers that correlate, or anti-correlate strongly with those in our diagnostic models, and which may be used as replacement biomarkers during future point of care test development if necessary. We converted the cerebrospinal fluid-derived biomarkers that were validated in the project into an ELISA-based test – a test format that can be implemented at district and tertiary hospitals; and developed three prototype point of care test variants through different engineering students. Co-funding from the South African Medical Research Council enabled the collaboration with an industrial partner who is based in Cape Town, South Africa, and with proven expertise in the development of point-of-care tests and led to the successful development of a lateral flow test for the diagnosis of the disease. We also developed another test variant that is based on “biosensors” – the technology that was also being pursued by one of the Engineering students. These tests are ready for large-scale clinical evaluation and gathering of data for regulatory approvals, with only further minor optimisations required if necessary.

Despite initial delays resulting from covid-19-related lockdown restrictions, all participant recruitment milestones for the project were met. Samples collected through the project led to the training of a total of 13 core project postgraduate students and postdoctoral fellows including one BSc Honours, four masters, three master’s in engineering, three PhD and two postdoctoral fellows. The study also provided specimens for research projects of four other  postgraduate students and postdoctoral fellows that were affiliated with the PI’s institution but not his research group.  Other major successes of the project included the granting of a patent application in the USA, with applications in other territories pending. At project conclusion, three peer reviewed papers and one conference proceedings paper had been published, with at least five other manuscripts being written up.  Study findings were disseminated at several local (based in South Africa) and international conferences. A spin-out company was being established to enable the future commercialisation of the tests developed in the project and other Stellenbosch University-related innovations, at the conclusion of project.

Current publications:

1. Manyelo CM, Solomons RS, Walzl G, Chegou NN. Tuberculous Meningitis: Pathogenesis, Immune Responses, Diagnostic Challenges, and the Potential of Biomarker-Based Approaches. J Clin Microbiol. 2021 Feb 18;59(3):e01771-20. doi: 10.1128/JCM.01771-20. PMID: 33087432; PMCID: PMC8106718.

2. Manyelo CM, Chegou NN, Seddon JA, Snyders CI, Mutavhatsindi H, Manngo PM, Walzl G, Stanley K, Solomons RS. Serum and cerebrospinal fluid host proteins indicate stroke in children with tuberculous meningitis. PLoS One. 2021 Apr 30;16(4):e0250944. doi: 10.1371/journal.pone.0250944. PMID: 33930055; PMCID: PMC8087017.

3. Manyelo CM, Solomons RS, Snyders CI, Kidd M, Kooblal Y, Leukes VN, Claassen C, Roos K, Stanley K, Walzl G, Chegou NN; TBMBIOMARKERS study group. Validation of host cerebrospinal fluid protein biomarkers for early diagnosis of tuberculous meningitis in children: a replication and new biosignature discovery study. Biomarkers. 2022 Sep;27(6):549-561. doi: 10.1080/1354750X.2022.2071991. Epub 2022 May 12. PMID: 35506251.

    

4. Eribo OA, Naidoo CC, Theron G, Walzl G, du Plessis N, Chegou NN. An Archetypical Model for Engrafting Bacteroides fragilis into Conventional Mice Following Reproducible Antibiotic Conditioning of the Gut Microbiota. Microorganisms. 2023 Feb 10;11(2):451. doi: 10.3390/microorganisms11020451. PMID: 36838416; PMCID: PMC9966493.

    

5. Kim D, Perold WJ, Chegou NN. Development of a Biosensor for the Early Detection of Tuberculous Meningitis in Infants. Engineering Proceedings. 2025; 109(1):12. DOI: https://doi.org/10.3390/engproc2025109012