Description

According to the theory of evolution, microbes are a primitive form of life. Among these

tiny organisms, bacteria are ubiquitous and present in the human body at a ratio of 10:1. Their abundancy has raised a query on their role in day-to-day life in humans, in spite of their potential in causing lethal infections, and their contributions in scavenging/decomposing organic wastes, strengthening the host immune response and elemental cycle viz. biogeo-chemical, carbon and nitrogen were also well-known. Hence, they are beneficial to human in various aspects; on the other hand highly harmful in the perspectives of infections and diseases.

Based on these facts, bacteria are broadly classified as pathogenic and non-pathogenic or harmless and harmful. The biological mechanism that leads to a diseased state by bacteria is called 'pathogenesis' and the seriousness of bacteria in inducing such state is called 'pathogenicity'. The pathogenicity of bacteria chiefly depends on the nature of virulence factors which dwell in their genome. In addition, they have a common mode of escaping strategies that have been practiced by several bacteria to evade the host immune system (Pieters 2001; Homef et al, 2002; Finlay and McFadden, 2006). Therefore, it appears that the virulence determinants of the pathogen may depend on any of its genetics, biochemical or structural features that produce the disease in the host by enabling the evading mechanism.

Microbial resistance to antibiotics has been considered as one of the most common evading strategies to cause illness in humans. Owing to this emerging characteristic resistance in pathogens, the "golden era" of modern medicine which saves the lives of several thousand through antibiotic treatment has been under serious threat. In 2013, the Centers for Disease Control and Prevention (CDC) released a landmark report on "Antibiotic Resistance Threats" in which the three pathogens viz. Klebsiella pneumoniae, Escherichia coli and Neisseria gonorrhea, were reported as resistance to almost all currently available antibiotics and have been.