BackgroundAvailability and access to the detection of resistance to anti-tuberculosis drugs remains a significant challenge in Malawi due to limited diagnostic services. The Xpert® MTB/RIF can detect Mycobacterium tuberculosis and resistance to rifampicin in a single, rapid assay. Rifampicin-resistant M. tuberculosis has not been well studied in Malawi.ObjectivesWe aimed to determine mutations in the rifampicin resistance determining region (RRDR) of the rpoB gene of M. tuberculosis strains which were defined as resistant to rifampicin by the Xpert MTB/RIF assay.MethodsRifampicin-resistant isolates from 43 adult patients (≥ 18 years) from various districts of Malawi were characterised for mutations in the RRDR (codons 507–533) of the rpoB gene by DNA sequencing.ResultsMutations were found in 37/43 (86%) of the resistant isolates in codons 511, 512, 513, 516, 522, 526 and 531. The most common mutations were in codons 526 (38%), 531 (29.7%) and 516 (16.2%). Mutations were not found in 6/43 (14%) of the resistant isolates. No novel rpoB mutations other than those previously described were found among the rifampicin-resistant M. tuberculosis complex strains.ConclusionThis study is the first to characterise rifampicin resistance in Malawi. The chain-termination DNA sequencing employed in this study is a standard method for the determination of nucleotide sequences and can be used to confirm rifampicin resistance obtained using other assays, including the Xpert MTB/RIF. Further molecular cluster analysis, such as spoligotyping and DNA finger printing, is still required to determine transmission dynamics and the epidemiological link of the mutated strains.

BackgroundXpert® MTB/RIF is a molecular test for the detection of Mycobacterium tuberculosis and rifampicin resistance. It is considered to be a great advance over smear microscopy and culture. However, there is very little information regarding the performance characteristics of Xpert MTB/RIF in Malawi.ObjectiveWe aimed to evaluate the performance of Xpert MTB/RIF in a Malawian setting.MethodsStored sputum pellets were processed on Xpert MTB/RIF between June 2012 and May 2014. Results were compared to mycobacteria growth indicator tube and Löwenstein-Jensen cultures, LED fluorescent microscopy and GenoType® MTBDRplus assay. Rifampicin resistance was confirmed by DNA sequencing.ResultsOf the 348 specimens with valid Xpert MTB/RIF results, 129/348 (37%) were smear-positive and 198/348 (57%) were culture-positive. Xpert MTB/RIF demonstrated a sensitivity of 93.8% (95% CI 89.4% – 96.8%) and specificity of 97.4% (95% CI 93.5% – 99.3%), with a positive predictive value of 97.8% (95% CI 94.6% – 99.4%) and a negative predictive value of 92.6% (95% CI 87.4% – 96.1%). Xpert MTB/RIF correctly identified 185/186 (99.5%) rifampicin-sensitive and 2/2 (100%) rifampicin-resistant M. tuberculosis strains. Mutations were not detected by sequencing in one isolate which was rifampicin resistant on Xpert MTB/RIF but sensitive on MTBDRplus. Four non-tuberculous mycobacteria grew from four smear-negative specimens, namely, M. avium (n = 1) and M. intracellulare (n = 3). No cross-reactivity was observed with any of the non-tuberculous mycobacteria when using Xpert MTB/RIF.ConclusionWhen fully implemented, Xpert MTB/RIF may have an impact on patient care in Malawi. The increased diagnostic yield of Xpert MTB/RIF over smear microscopy can increase laboratory-confirmed tuberculosis detection and ensure that treatment is given to appropriate individuals or groups.

Treatment options for Epstein-Barr virus (EBV)-associated Burkitt lymphoma in Africa are limited because of chemotherapy-associated toxicity. Since other EBV-associated diseases respond to antiviral agents, we investigated adding an antiviral agent, valacyclovir, to the current chemotherapy regimen in Malawi. In this phase I safety study, we showed that cyclophosphamide combined with valacyclovir was safe. Phase II efficacy trials should now be undertaken. Background Nucleoside analogues, including acyclovir, ganciclovir, and their precursors, have shown some efficacy against several Epstein-Barr virus (EBV)-associated diseases, including active EBV infection and posttransplantation lymphoproliferative disorder (PTLD). They have also been proposed as a possible treatment for EBV-associated malignancies, including endemic Burkitt lymphoma. The safety of nucleoside analogues in combination with chemotherapy in the developing world has not been studied and is necessary before any large scale efficacy trials are conducted. Patients and Methods Children 3–15 years old meeting inclusion criteria were assigned to a 3+3 dose escalation trial of combination valacyclovir (15 and 30 mg/kg, 3 times daily for 40 days) and cyclophosphamide (CPM) (40 mg/kg day 1, 60 mg/kg on days 8, 18, and 28) or CPM monotherapy. Subjects were monitored for clinical and laboratory toxicity and had EBV levels measured regularly. Dose-limiting toxicity (DLT) was our primary outcome. Results We found that the combination of valacyclovir and CPM was safe and did not lead to any DLT compared with CPM monotherapy. The most common side effects were vomiting, abdominal pain, and tumor site pain, which were similar in both arms. Patients with measurable serum EBV showed decreased loads over their treatment course. Conclusions We recommend a phase II valacyclovir dose of 30 mg/kg 3 times daily for 40 days. We also observed that 6 of our 12 patients with presumed Burkitt lymphoma had measurable EBV viral loads that decreased over the course of their treatment, suggesting that phase II studies should investigate this correlation further. This study paves the way for a phase II efficacy trial of combined valacyclovir and CPM in the treatment of endemic Burkitt lymphoma.

No abstract