Introduction
Most of the microorganisms naturally present in the human body are harmless commensals. However, there also exists other disease causing microorganisms known as pathogens and the mechanism by which they cause disease is known as pathogenesis. These pathogens persist or multiply within the host causing infection. Some pathogens like Pseudomonas aeruginosa are considered as opportunistic pathogens that cause disease only in patients with compromised immunity and only under certain conditions. The infectious diseases may be treated with antibiotic drugs. However, it is important to know the different types of pathogens and the virulence factors by which they cause disease ...