Bacterial enteric pathogens are by far the most dominant scourge of mankind.
There are more than 200 million cases and 3 million deaths caused by these bacteria every
year. Before the antimicrobial era, there were pandemics of enteric diseases which
sometimes swept away whole populations. Advent of antimicrobial era provided a tool in
the hand of mankind to fight this menace. In the beginning the results were promising and
there was optimism of a decisive victory against disease causing bacteria. But the reality
dawned within a couple of decades when antimicrobial resistance started to emerge and
every new antimicrobial was generally knocked out in a couple of years. It became
apparent that these bacteria held a distinct advantage because of very fast evolution rate due
to relatively simple and small genome and short generation time. Currently, we are always
playing a catch up game because the enemy is always ahead. The emergence of multiple
drug resistance (MDR) has aggravated the situation and there is a distinct possibility that
some of these menacing bugs may get out of control and situation of pre-antimicrobial era
may return. Recently, a new term extreme-drug resistance (XDR) has been coined. This
refers to bacteria resistant to all available drugs. This aptly summarizes the situation we are
facing today. This catastrophe can only be avoided by putting more efforts in developing
new concepts and products. This chapter is an effort to encompass the properties of these
pathogens, the antimicrobials currently in use and the mechanisms of drug resistance
evolved by these formidable bacteria.
Keywords: Antimicrobial drug resistance, human enteric pathogens, molecular
mechanisms.