Semail, Noreafifah
(2019)
Respiratory microbiome and its susceptibility to Mycobacterium tuberculosis infection.
Masters thesis, Universiti Sains Malaysia.
Abstract
Respiratory throat acts as an ecological niche for various microorganisms. These
microbial communities play important roles in the maintenance of human health.
Although the interest in microbial composition of microbiota in respiratory tracts has
recently been increased, the possible relationship between the composition and abundance
of microbiota in the ecological niche of human throat with Mycobacterium tuberculosis
infection are poorly understood. This study was aimed to investigate the composition of
throat microbiota in pulmonary tuberculosis patients in comparison to healthy TST
(Tuberculin Skin Test) positive and TST negative subjects. The microbiota of the throat
was fully characterized by 16s rRNA Metagenomics sequencing. The study revealed that
altogether, there were 7 phyla and 35 genera in the throat of enrolled subjects. The main
phyla were Firmicutes, Bacteriodetes, Proteobacteria and Actinobacteria. The
predominant communities of genera were Streptococcus, Staphylococcus,
Capnocytophaga, Rothia and Enterococcus. The microbiota composition of TB patients
and asymptomatic TST positive subjects were more heterogeneous as compared to the
throat microbiota of healthy TST negative subjects. Streptococcus was found to be
significantly abundant in throat of healthy compared to asymptomatic TST positive
subjects and TB patients. In TB patients, Bifidobacterium, Bulleidia, Butyrivibrio,
Chryseobacterium and Pediococcus were among the genera present abundantly in their
throats compared to TST negative. At genus level, Lactobacillus salivarius was
significantly higher in the throat of TB patients compared to TST positive individuals.
Streptococcus sobrinus and Bulleidia moorei were also significantly higher in TB patients
when compared with those in the throats of TST negative individuals. Alpha diversity and
beta diversity analysis were also performed in this study. No significant difference was
observed between the three groups in alpha indices indicating the equally diverse
microbiota in terms of richness and evenness of the species. In beta diversity analysis, the
unweighted unifrac of TB patients and TST negative groups were statistically higher
compared to TST positive group, indicating the higher presence of particular cluster or
species in their throats. Weighted unifrac of TST positive was statistically higher than that
of TB patients and TST negative groups which indicates more distantly related organisms
inhabiting the communities. This investigation was consistent with earlier studies and our
findings indicate that throat microbiota may play a role in the susceptibility or resistance
to Mycobacterium tuberculosis infection. The relevance of these microbiota may need to
be taken into consideration to improve methods of control of TB disease in the future.
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