Global spread of antimicrobial resistant bacteria has becoming serious threat. Infectious diseases with resistant bacteria have a higher mortality rate, and their treatments are higher expensive than those with sensitive strains. WHO distributed global report on antimicrobial resistant bacteria and their surveillance on 2014. Since human being developed antibiotics, emergence of antimicrobial resistant bacteria inevitably occurred. Many of guidelines for infectious diseases propose proper use of antibiotics in order to prevent generation and spread of antimicrobial resistant bacteria. Bacteria can remarkably evolve, so antimicrobial resistant bacteria easily generate in the presence of antibiotics. Bacteria acquire the resistance by not only spontaneous mutations in genome but also acquisition of exogenous resistance gene using various mechanisms. This paper summarizes basic knowledge concerning the antimicrobial resistant bacteria, and describes how bacteria acquire skillfully and easily the resistance that are learned from examples of our studies.
