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This chapter focuses on intestinal microbiota and its effect on drug metabolism. Here, we discussed about different drugs which are metabolized either by some enzymes or gut microbiota and their mechanism. Nowadays, consuming drugs without a doctor's prescription is common. This chapter will make people aware about its negative consequences and how it is related to gut microbiota dysbiosis. Intestinal disorders like inflammatory bowel disease (IBD), colorectal cancer (CRC) and metabolic disorders such as obesity and type 2 diabetes mellitus (T2D) are found to be affected with gut microbiota dysbiosis. To address this issue, we discussed a variety of strategies such as fecal microbiota transplantation (FMT), probiotics and antibiotic stewardship programs which are commonly used to tackle this problem.

Helicobacter pylori is a ubiquitous bacterium and contributes significantly to the burden of chronic gastritis, peptic ulcers, and gastric cancer across the world. Adaptive phenotypes and virulence factors in H. pylori are heterogeneous and dynamic. However, limited information is available about the molecular nature of antimicrobial resistance phenotypes and virulence factors of H. pylori strains circulating in India. In the present study, we analyzed the whole genome sequences of 143 H. pylori strains, of which 32 are isolated from two different regions (eastern and southern) of India. Genomic repertoires of individual strains show distinct region-specific signatures. We observed lower resistance phenotypes and genotypes in the East Indian (Kolkata) H. pylori isolates against amoxicillin and furazolidone antibiotics, whereas higher resistance phenotypes to metronidazole and clarithromycin. Also, at molecular level, a greater number of AMR genes were observed in the east Indian H. pylori isolates as compared to the southern Indian isolates. From our findings, we suggest that metronidazole and clarithromycin antibiotics should be used judicially in the eastern India. However, no horizontally acquired antimicrobial resistance gene was observed in the current H. pylori strains. The comparative genome analysis shows that the number of genes involved in virulence, disease and resistance of H. pylori isolated from two different regions of India is significantly different. Single-nucleotide polymorphisms (SNPs) based phylogenetic analysis distinguished H. pylori strains into different clades according to their geographical locations. Conditionally beneficial functions including antibiotic resistance phenotypes that are linked with faster evolution rates in the Indian isolates.

Microbes evolve rapidly by modifying their genome through mutations or acquisition of genetic elements. Antimicrobial resistance in Helicobacter pylori is increasingly prevalent in India. However, limited information is available about the genome of resistant H. pylori isolated from India. Our pan- and core-genome based analyses of 54 Indian H. pylori strains revealed plasticity of its genome. H. pylori is highly heterogenous both in terms of the genomic content and DNA sequence homology of ARGs and virulence factors. We observed that the H. pylori strains are clustered according to their geographical locations. The presence of point mutations in the ARGs and absence of acquired genetic elements linked with ARGs suggest target modifications are the primary mechanism of its antibiotic resistance. The findings of the present study would help in better understanding the emergence of drug-resistant H. pylori and controlling gastric disorders by advancing clinical guidance on selected treatment regimens.

Efforts to produce vaccines against SARS and MERS were prematurely halted since their scope was perceived to be geographically restricted and they were subsequently categorized as neglected diseases. However, when a similar virus spread globally triggering the COVID-19 pandemic, we were harshly reminded that several other neglected diseases might also be waiting for the perfect opportunity to become mainstream. As climate change drives urbanization, natural selection of pathogens and their intermediate vectors and reservoirs, the risk of neglected diseases emerging within a larger susceptible pool becomes an even greater threat. Availability of a vaccine for COVID-19 is widely considered the only way to end this pandemic. Similarly, vaccines are also seen as the best tools available to control the spread of neglected (sometimes referred to as emerging or re-emerging) diseases, until the water, hygiene and sanitation infrastructure is improved in areas of their prevalence. Vaccine production is usually cost and labour intensive and thus minimal funding is directed towards controlling and eliminating neglected diseases (NDs). A customised but sustainable approach is needed to develop and deploy vaccines against NDs. While safety, efficacy and public trust are the three main success pillars for most vaccines, affordability is vital when formulating vaccines for neglected diseases.