Plasmids: The Necessary Knowledge Wealth for Encountering Antibiotic-Resistance Menace

Abstract

Infections caused by multidrug resistant bacteria have been identified as an emergent global public health problem as it significantly increases the rate of morbidity and mortality and simultaneously health care costs. It has already been identified that the foremost cause of mortality by the mid of twenty-first century would be drug-resistant disease having direct implication in annual direct costs amounting to 2–3% of the global output GDP. European Center for Disease Prevention and Control (ECDC) and the Center for Disease control and Prevention (CDC) have jointly made the definitions for MDR (multidrug resistant), XDR (extensively or extremely drug resistant) and PDR (Pan drug resistance). Only acquired antimicrobial resistance but not intrinsic resistance was considered for defining MDR, XDR and PDR types. The consecutive development of drug resistance in a population occurs stepwise and organisms with low-level resistance may form the genetic platform for the development of higher resistance levels. Molecular analyses have revealed that widespread multi resistance has commonly been achieved by the acquisition of preexisting determinants followed by amplification in response to selection (acquired resistance). Plasmids, being an important carrier of mobile genetic elements bearing antibiotic resistance genes, play a fundamental role in the dissemination of antimicrobial resistance genes within the gene pool. Certain connections between antibiotic-resistant plasmids and pathogenic bacterial clones are hugely extensive. Plasmids, mainly the conjugative ones are undoubtedly the most significant drivers of antibiotic-resistance dissemination in the bacterial families such as Enterobacteriaceae and Enterococcaceae, which comprise some of the most important hospital-borne- pathogens. Role of plasmids in developing antibiotic resistance and also endemic and epidemic behavior in certain important pathogenic bacterial genera like Pseudomonas, Acinetobacter baumanii, Staphylococcus aureus have been evidenced from several studies. Survival of these bacterial pathogens in different challenging environments is mediated mainly by plasmids. In the near future, scientists will be able to blend the technological and theoretical knowledge in clubbing genomics, transcriptomics, proteomics and metabolomics to delineate the molecular basis of the fitness-cost and compensation in plasmid–bacterium relationships