Mechanisms of Antimicrobial Resistance

There is no doubt that antimicrobial agents have saved the human race from a lot of suffering due to infectious disease burden. Without antimicrobial agents, millions of people would have succumbed to infectious diseases. Man has survived the accidental wrath of microorganisms using antimicrobial agents and other mechanisms that keep them at bay. Hardly years after the discovery and use of the first antibiotics was observation made of organisms that still survived the effects of the antimicrobial agents. That was the beginning of the suspicion that different microorganisms were getting a way around previously harmful agents that is known today as antimicrobial resistance. Microbial resistance to antimicrobial agents was not a new phenomenon for it had been constantly used as competitive/survival mechanisms by microorganisms against others. These mechanisms have been well documented. This chapter therefore gives a brief overview of the mechanisms of resistance by bacteria against antimicrobial agents, and the mechanisms, levels, and patterns of resistance to the different microorganisms in developing countries are dealt with in detail elsewhere in the book. Understanding the mechanisms of resistance is important in order to define better ways to keep existing agents useful for a little longer but also to help in the design of better antimicrobial agents that are not affected by the currently known, predicted, or unknown mechanisms of resistance.