Use of light-emitting diode fluorescence microscopy to detect acid-fast bacilli in sputum as proficient alternative tool in the diagnosis of pulmonary tuberculosis in countries with limited resource settings

Background

Despite recent advances in the development of more sensitive technologies for the diagnosis of tuberculosis (TB), in resource-limited settings, the diagnosis continues to rely on sputum smear microscopy. This is because smear microscopy is simple, cost-efficient and the most accessible tool for the diagnosis of TB. Our study evaluated the performance of light-emitting diode fluorescence microscopy (LED-FM) using auramine/rhodamine (auramine) and the fluorescein di-acetate (FDA) vital stain in the diagnostic of pulmonary TB in Bamako, Mali.

Methods

Sputum smear microscopy was conducted using the FDA and auramine/rhodamine staining procedures on fresh samples using LED-FM to evaluate the Mycobacterium TB (MTB) metabolic activity and to predict contagiousness. Mycobacterial culture assay was utilized as a gold standard method.

Results

Out of 1401 TB suspected patients, 1354 (96.65%) were retrieved from database, which were MTB complex culture positive, and 47 (3.40%) were culture negative (no mycobacterial growth observed). Out of the 1354 included patients, 1343 (95.86%), were acid-fast bacillus (AFB) positive after direct FDA staining, 1352 (96.50%) AFB positive after direct Auramine, and 1354 (96.65%) AFB positive with indirect auramine after digestion and centrifugation. Overall, the FDA staining method has a sensitivity of 98.82%, while the sensitivity of Auramine with direct observation was 99.48%, and 99.56% with the indirect examination.

Conclusion

This study showed that, using fresh sputum both auramine/rhodamine and FDA are highly sensitive methods in diagnosing pulmonary TB and could be easily used in countries with limited resource settings.

Dynamics of SARS-CoV-2 variants characterized during different COVID-19 waves in Mali

Background

The emergence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variants may have contributed to prolonging the pandemic, and increasing morbidity and mortality related to coronavirus disease 2019 (COVID-19). This article describes the dynamics of circulating SARS-CoV-2 variants identified during the different COVID-19 waves in Mali between April and October 2021.

Methods

The respiratory SARS-CoV-2 complete spike (S) gene from positive samples was sequenced. Generated sequences were aligned by Variant Reporter v3.0 using the Wuhan-1 strain as the reference. Mutations were noted using the GISAID and Nextclade platforms.

Results

Of 16,797 nasopharyngeal swab samples tested, 6.0% (1008/16,797) tested positive for SARS-CoV-2 on quantitative reverse transcription polymerase chain reaction. Of these, 16.07% (162/1008) had a cycle threshold value ≤28 and were amplified and sequenced. The complete S gene sequence was recovered from 80 of 162 (49.8%) samples. Seven distinct variants were identified: Delta (62.5%), Alpha (1.2%), Beta (1.2%), Eta (30.0%), 20B (2.5%), 19B (1.2%) and 20A (1.2%).

Conclusions and perspectives

Several SARS-CoV-2 variants were present during the COVID-19 waves in Mali between April and October 2021. The continued emergence of new variants highlights the need to strengthen local real-time sequencing capacity and genomic surveillance for better and coordinated national responses to SARS-CoV-2.

Isoniazid preventive therapy in child household contacts of adults with active TB in Bamako, Mali

BACKGROUND AND OBJECTIVE

Isoniazid preventive therapy (IPT) is known to reduce the risk of developing active TB in about 59% in children aged ⩽15 years. We assessed adherence, completion and adverse events among children who were household contacts of a newly diagnosed adult with smear-positive TB in Bamako, Mali.

METHODS

Children aged <15 years living in the same house with an adult smear-positive index case were enrolled in the study in the Bamako Region after consent was obtained from the parent or legal guardian. Adherence was assessed based on the number of tablets consumed during 6 months.

RESULTS

A total of 260 children aged <15 years were identified as household contacts of 207 adult patients with smear-positive TB during the study period. Among all child contacts, 130/260 (50.0%) were aged 0-4 years and were eligible for IPT; 128/130 (98.5%) were started on IPT and 83/128 (64.8%) completed with good adherence at the end of the 6 months, and without any significant adverse events.

CONCLUSION

We successfully implemented IPT with good acceptance, but low completion rate. The Mali National TB Program and partners should expand this strategy to reach more children in Bamako and the whole country and create greater awareness in the population.