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.

Sources: TH