THE DRUG RESISTANCE IN MICROORGANISM: A REVIEW REPORT

Abstract

Multiple antibiotic resistance in bacteria was at first thought to be caused exclusively by the combination of several resistance genes, each coding for resistance to a single drug. More recently, it became clear that such phenotypes are often achieved by the activity of drug efflux pumps. Some of these efflux pumps exhibit an extremely wide specificity covering practically all antibiotics, chemotherapeutic agents, detergents, dyes, and other inhibitors, the exception perhaps being very hydrophilic compounds. Such efflux pumps work with exceptional efficiency in Gram-negative bacteria through their synergistic interaction with the outer membrane barrier. It is disturbing that the antibacterial agents of the most advanced type, which are unaffected by common resistance mechanisms, are the compounds whose use appears to select for multidrug-resistant mutants that overproduce these efflux pumps of wide specificity.

Since the introduction of antibiotics, bacteria have not only evolved elegant resistance mechanisms to thwart their effect, but have also evolved ways in which to disseminate themselves or their resistance genes to other susceptible bacteria. During the past few years, research has revealed not only how such resistance mechanisms have been able to evolve and to rapidly disseminate, but also how bacteria have, in some cases, been able to adapt to this new burden of resistance with little or no cost to their fitness. Such adaptations make the control of these superbugs all the more difficult.