Pooling of sputum samples to increase tuberculosis diagnostic capacity in Brazil during the COVID-19 pandemic

Objectives We assessed whether combining (pooling) four individual's samples and testing with Xpert Ultra has the same accuracy as testing samples individually, as a more efficient testing method. Methods We conducted a cross-sectional study of individuals with presumptive TB attending primary health care or general hospital facilities in Alagoas, Brazil. Sputum samples of four consecutive individuals were pooled and the pool and individual samples were tested with Xpert Ultra. The agreement of the tests was compared using kappa statistics. We estimated the sensitivity and specificity of pooling using the individual test as the reference standard and potential cartridge savings. Results Three hundred and ninety-six participants were tested. Ninety-five (24.0%) individual samples were MTB-positive, 300 (75.8%) MTB-not detected, including 20 MTB-trace, and one reported an error. Ninety-nine pools of four samples were tested, of which 62 (62.6%) had MTB-detected and 37 (37.4%) MTB-not detected, including six (6.1%) with MTB-trace. The agreement of individual and pooled testing was 96.0%. Pooling had sensitivity of 95.0% (95%CI 86.9%–99%), specificity of 97.1% (95%CI 85.1%–99.9%) and Kappa of 0.913. The method saved 12.4% of cartridge costs. Conclusion The pooled testing of specimens had a high level of agreement with individual testing. Pooling of samples for testing improves the efficiency of testing, potentially enabling the screening and testing of larger numbers of people more cost-effectively

Use of V H, D and J H immunoglobulin gene segments in Brazilian patients with chronic lymphocytic leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is a haematological malignancy for which reliable prognostic markers are needed in view of its clinical heterogeneity. In approximately 50% of CLL patients, immunoglobulin (Ig) rearrangements are modified by somatic hypermutation (SHM), a process that represents a reliable prognostic indicator of favourable progression. In this study, we investigated SHM in 37 Brazilian CLL patients and identified the preferential involvement of specific immunoglobulin gene families and segments through PCR-amplified fragments or subcloned fragments. Forty-one rearrangements were observed and 37 of them were functional. A 98% homology cut-off with germinal sequences showed 18 patients (48.7%) with SHM. Unmutated cases showed a poorer clinical outcome. V H3 was the most frequent V H family, followed by V H4. The V H4-39 segment was the most frequently used, mainly in unmutated cases, while the V H3 family was predominant in mutated cases. The D3 and J H4/J H6 families were the most frequently observed

Pooling of sputum samples to increase tuberculosis diagnostic capacity in Brazil during the COVID-19 pandemic

Objectives: We assessed whether combining (pooling) four individual's samples and testing with Xpert Ultra has the same accuracy as testing samples individually as a more efficient testing method. Methods: We conducted a cross-sectional study of individuals with presumptive tuberculosis attending primary health care or general hospital facilities in Alagoas, Brazil. The sputum samples of four consecutive individuals were pooled and the pool and individual samples were tested with Xpert Ultra. The agreement of the tests was compared using kappa statistics. We estimated the sensitivity and specificity of pooling using the individual test as the reference standard and potential cartridge savings. Results: A total of 396 participants were tested. A total of 95 (24.0%) individual samples were Mycobacterium tuberculosis (MTB)-positive, 300 (75.8%) “MTB not detected”, including 20 “MTB trace”, and one reported an error. A total of 99 pools of four samples were tested, of which 62 (62.6%) had MTB detected and 37 (37.4%) MTB not detected, including six (6.1%) with MTB trace. The agreement between individual and pooled testing was 96.0%. Pooling had a sensitivity of 95.0% (95% confidence interval 86.9-99%), specificity of 97.1% (95% confidence interval 85.1-99.9%), and kappa of 0.913. The method saved 12.4% of cartridge costs. Conclusion: The pooled testing of specimens had a high level of agreement with individual testing. The pooling of samples for testing improves the efficiency of testing, potentially enabling the screening and testing of larger numbers of individuals more cost-effectively