Multi-Drug Resistance (MDR)


    In News

    New research from the Population Biology Lab at IISER Pune made an observation that some bacteria evolve multidrug resistance while others do not.


    Key Findings

    • The antibiotics exert a very strong selection pressure, it would appear that every bacteria in nature can become multidrug resistant, which is not the case.
    • One of the reasons given for why that does not happen is fitness cost.
    • When bacteria become fit in one environment, they either lose fitness or fail to increase fitness in other environments. 
    • The study shows that when the environment is fluctuating, large(but not small) populations can bypass the effect of multidrug resistance (MDR).


    Effect of Population size

    • The study showed that, all else being equal, whether the bacteria pay fitness costs or not will depend on the population size they evolve in. 
    • On doing whole genome, whole population sequencing, the researchers found that the larger populations contained a greater number of mutations. 
    • The smaller populations only had mutations related to metabolism of one kind of carbon source whereas the larger populations had known mutations for metabolism of multiple types of carbon sources.
    • This could be the reason that the larger populations were able to bypass the costs.
    • Thus, population size determines the kind of mutations available to the bacteria, which in turn, leads to multidrug resistance (MDR) or not.


    Multiple drug resistance (MDR)

    • It is antimicrobial resistance (AMR) shown by a species of microorganism to at least one antimicrobial drug in three or more antimicrobial categories.
    • The various MDR types are as following:
      • MDR bacteria that resist multiple antibiotics (most threatening to public health); 
      • MDR viruses, parasites (resistant to multiple antifungal, antiviral, and antiparasitic drugs of a wide chemical variety).
    • In terms of different degrees of MDR in bacteria, 
      • Extensively drug-resistant (XDR) and 
      • pandrug-resistant (PDR). 
    • Extensively drug-resistant (XDR) is the non-susceptibility of one bacteria species to all antimicrobial agents except in two or less antimicrobial categories. 


    Challenges of Multidrug resistance (MDR) 

    • It is a menace in public health and a global health and development threat. 
    • Misuse and overuse of antimicrobials are the main drivers in the development of drug-resistant pathogens.
    • The bacteria is adept at handling multiple antibiotics simultaneously. 
    • It increases the fitness of bacteria appreciably which is difficult to treat.
    • WHO has declared that antimicrobial resistance is one of the top 10 global public health threats facing humanity.
    • Lack of clean water and sanitation and inadequate infection prevention and control promotes the spread of microbes, some of which can be resistant to antimicrobial treatment.
    • The cost of AMR to the economy is significant. 
    • In addition to death and disability, prolonged illness results in longer hospital stays, the need for more expensive medicines and financial challenges for those impacted.


    Way Ahead

    • MDR is a complex problem that requires a united multisectoral approach.
    • It requires urgent multisectoral action in order to achieve the Sustainable Development Goals (SDGs).
    • Use the appropriate antimicrobial for an infection; e.g. no antibiotics for viral infections.
    • Identify the causative organism whenever possible;
    • Select an antimicrobial which targets the specific organism, rather than relying on a broad-spectrum antimicrobial;
    • Complete an appropriate duration of antimicrobial treatment (not too short and not too long);
    • Use the correct dose for eradication; subtherapeutic dosing is associated with resistance, as demonstrated in food animals;
    • More thorough education of and by prescribers on their actions’ implications globally.

    Global Action Plan on Antimicrobial Resistance (GAP)

    • Globally, countries committed to the framework set out in the Global Action Plan1 (GAP) 2015 on AMR during the 2015 World Health Assembly.
    • Committed to the development and implementation of multisectoral national action plans. 
    • It was subsequently endorsed by the Governing Bodies of the Food and Agriculture Organization of the United Nations (FAO) and the World Organisation for Animal Health (OIE). 
    • To ensure global progress, countries need to ensure costing and implementation of national action plans across sectors to ensure sustainable progress. 
    • Prior to the endorsement of the GAP in 2015, global efforts to contain AMR included the WHO global strategy for containment of Antimicrobial Resistance developed in 2001 which provides a framework of interventions to slow the emergence and reduce the spread of AMR.


    Sources: TH