Determination of anti-tuberculosis activity of biosynthesized gold nanocompounds against M. tuberculosis H37RV

BACKGROUND

The biosynthesis of gold nanoparticles using medicinal plants as reducing and stabilizing agent for synthesis is an emerging area of research due to their cost effectiveness and further diversified applications in various fields. People with HIV are prone to these opportunistic infections like TB due to the immunocompromised condition. In the present study, the nanoparticles and nanoconjugates were screened for effective anti-mycobacterial efficiency against opportunistic infections.

METHODS

Incidentally, the nanoparticles were biosynthesized using single plant extract. The biosynthesized nanoparticles were initially screened for effective anti-tuberculosis activity against Mycobacterium tuberculosis. Based on the effective antimicrobial activity, a nanoconjugate was biosynthesized combining three plant extracts for a cumulative activity.

RESULTS

The biosynthesized gold nanoparticles and nanoconjugates showed MIC demonstrating for 99% inhibition and MIC99 was found to be 6.42 μg/ml. Among all the 15 nanoparticles tested, seven NPs showed exceptional anti-TB activities NP1, NP2, NP6, NP7, NP10, NP12 and NP15 and the other nanoparticles exhibited varying degrees of inhibition - anti-TB activities. In the 12 nanoconjugate tested, seven nanoconjugate demonstrated exceptional anti-TB activities such as NCC1, NCC2, NCC5, NCC6, NCV1, NCV6 and NCV4.

CONCLUSION

The objective of the study was to identify the nanoparticles and nanoconjugates which demonstrated potential activity against M. tuberculosis so that a single nanoparticle or nanoconjugate can be targeted to treat patients with TB. Minimum Inhibitory Concentration (MIC) of the biosynthesized gold nanoparticles and nanoconjugates were determined against M. tuberculosis H37Rv.

Prevalence of pulmonary tuberculosis among the tribal populations in India

Importance

There is no concrete evidence on the burden of TB among the tribal populations across India except for few studies mainly conducted in Central India with a pooled estimation of 703/100,000 with a high degree of heterogeneity.

Objective

To estimate the prevalence of TB among the tribal populations in India.

Design, participants, setting

A survey using a multistage cluster sampling design was conducted between April 2015 and March 2020 covering 88 villages (clusters) from districts with over 70% tribal majority populations in 17 States across 6 zones of India. The sample populations included individuals ≥15 years old.

Main outcome and measures

Eligible participants who were screened through an interview for symptoms suggestive of pulmonary TB (PTB); Two sputum specimens were examined by smear and culture. Prevalence was estimated after multiple imputations for non-coverage and a correction factor of 1.31 was then applied to account for non-inclusion of X-ray screening.

Results

A total of 74532 (81.0%) of the 92038 eligible individuals were screened; 2675 (3.6%) were found to have TB symptoms or h/o ATT. The overall prevalence of PTB was 432 per 100,000 populations. The PTB prevalence per 100,000 populations was highest 625 [95% CI: 496–754] in the central zone and least 153 [95% CI: 24–281] in the west zone. Among the 17 states that were covered in this study, Odisha recorded the highest prevalence of 803 [95% CI: 504–1101] and Jammu and Kashmir the lowest 127 [95% CI: 0–310] per 100,000 populations. Findings from multiple logistic regression analysis reflected that those aged 35 years and above, with BMI <18.5 Kgs /m², h/o ATT, smoking, and/or consuming alcohol had a higher risk of bacteriologically positive PTB. Weight loss was relatively more important symptom associated with tuberculosis among this tribal populations followed by night sweats, blood in sputum, and fever.

Conclusion and relevance

The overall prevalence of PTB among tribal groups is higher than the general populations with a wide variation of prevalence of PTB among the tribal groups at zone and state levels. These findings call for strengthening of the TB control efforts in tribal areas to reduce TB prevalence through tribal community/site-specific intervention programs.

Characterization of temperate phage Che12 and construction of a new tool for diagnosis of tuberculosis

A temperate phage, Che12, able to infect Mycobacterium tuberculosis, was isolated from soil samples taken from tuberculosis sanatorium area in Chennai, India. The plaque morphology of this phage showed varying grades of turbidity on lawns of M. tuberculosis. The temperate nature of Che12 was established by super infection immunity. Phage integration into the host genomic DNA was confirmed by Southern hybridization using Che12 DNA as a probe. PCR amplification and sequencing of a part of the integrated phage genome in a M. tuberculosis lysogen also confirmed the temperate nature of Che12. The morphology of the phage particles was observed by electron microscopy, revealing similarities to other mycobacteriophages like L5, D29 and TM4. A luciferase reporter phage, phAETRC16, was constructed by cloning firefly luciferase gene into Che12. Infection of viable M. tuberculosis cells by phAETRC16 resulted in expression of luciferase leading to sustained light output. Che12, a true temperate phage infecting M. tuberculosis, is thus ideally suited for developing a diagnostic tool facilitating rapid diagnosis of M. tuberculosis.