Context: 

• New research from the Population Biology Lab at IISER Pune could hold a key to the question of why some bacteria evolve multi-drug resistance while others do not.

 

 

Multi-drug resistance:

• It is a menace in public health, however, it is a fascinating problem to an evolutionary biologist who sees it from this angle: 
• Possessing multi-drug resistance implies that the bacteria is adept at handling multiple antibiotics simultaneously.
• This would increase its fitness appreciably. 
• Given that antibiotics exert a very strong selection pressure, it would appear that every bacteria in nature can become multi-drug resistant, which is not the case.

 

 

Key Highlights of the Study:

• The scientist group studied approximately 480 generations of E. coli in four types of steady environments consisting of different carbon sources: 
  • Galactose, 
  • Thymidine, 
  • Maltose and 
  • Sorbitol. 
• They also perform a study in one fluctuating environment in which the carbon source changed unpredictably between these four.
• It was found that bacteria cannot use all carbon sources similarly. 
  • Which carbon source is available impacts the bacterium’s ability to survive and grow.
• It was found that small populations acquire a certain set of mutations that allow them to survive in one environment while paying a cost in others. 
• Large populations also develop these mutations but, in addition, have certain compensatory mutations that together give them fitness to survive in different environments.
  • Thus, population size determines the kind of mutations available to the bacteria, which in turn, leads to the type of fitness costs they evolve.
  • The larger populations contained a greater number of mutations.
  • The smaller populations only had mutations related to the metabolism of one kind of carbon source whereas the larger populations had known mutations for the metabolism of multiple types of carbon sources.
• So the study concluded that when the environment is fluctuating, large (but not small) populations can by-pass this effect.

 

Anti Microbial Resistance

• Antimicrobial resistance is the resistance acquired by any microorganism against antimicrobial drugs (such as antibiotics, antifungals, antivirals, antimalarials, and anthelmintics) that are used to treat infections.
• A person cannot become resistant to antibiotics because resistance is a property of the microbe, not a person or other organism infected by a microbe.
• Microorganisms that develop antimicrobial resistance are sometimes referred to as “superbugs”.

 

How does Antimicrobial Resistance occur?

• Microbes can become resistant to drugs for both biological and social reasons. Microbial behavior
• As soon as scientists introduce a new antimicrobial drug, there is a good chance that it will become ineffective at some point in time.
• This is primarily due to changes occurring within the microbes.
• These changes can come about in different ways:

1. Mutation

• When microbes reproduce, genetic mutations can occur.
• Sometimes, this will create a microbe with genes that help it survive in the face of antimicrobial agents.

      2. Selective pressure

• Microbes that carry these resistance genes survive and replicate.
• The newly generated resistant microbes eventually become the dominant type.

      3. Gene transfer

• Microbes can pick up genes from other microbes.
• Genes conferring drug resistance can easily transfer between microbes.

     4. Phenotypic change

• Microbes can change some of their characteristics to become resistant to common antimicrobial agents.

 

 

Examples of resistance 

• Antimicrobial resistance can occur in bacteria, viruses, fungi, and parasites. Below are some examples:

1. Tuberculosis (TB)

• Globally, 4,80,000 people develop multi-drug resistant TB each year, and drug resistance is starting to complicate the fight against the airborne disease.

      2. Methicillin-resistant Staphylococcus aureus (MRSA):

• Methicillin-resistant Staphylococcus aureus (MRSA) is an infection caused by Staphylococcus (staph) bacteria.
• This type of bacteria is resistant to many different antibiotics.
• People usually get MRSA when they are staying in a hospital.
• In the past, it was a well-controlled infection, but now the disease is turning into a major public health concern due to antibiotic resistance.

     3. Gonorrhea:

• Gonorrhea is a sexually transmitted bacterial infection.
• Many cases of drug-resistant gonorrhea have started to occur all around the world.
• Currently, there is only one type of drug that is still effective against the drug-resistant form of this disease.

     4. Escherichia coli (E. coli):

• This bacterium is a common cause of food-borne disease and urinary tract infections.
• The rate of antibiotic resistance in E. coli is increasing quickly.

     5. Malaria:

• Mosquitoes spread this parasitic disease, which killed around 445,000 people worldwide in 2016.
• Antimalarial drugs are now ineffective in many parts of the world as drug-resistant parasites have evolved.

• India carries one of the largest burdens of drug-resistant pathogens worldwide, including the highest burden of multidrug-resistant tuberculosis, alarmingly high resistance among Gram-negative and Gram-positive bacteria.
• Regional studies report high AMR among pathogens such as Salmonella More Details typhi, Shigella, Pseudomonas, and Acinetobacter.
• Annually, more than 50,000 newborns are estimated to die from sepsis due to pathogens resistant to first-line antibiotics.
• While exact population burden estimates are not available, neonates and elderly are thought to be worse affected.
• Two million deaths are projected to occur in India due to AMR by the year 2050.
• It is no surprise that the emergence of enzyme New Delhi Metallo-β-lactamase (NDM-1), named after the national capital of India, in 2008 rapidly spread to other countries.

 

Government policies to combat Antimicrobial resistance

• The National Health Policy 2017 highlights the problem of antimicrobial resistance and calls for effective action to address it.
• The Ministry of Health & Family Welfare (MoHFW)  identified AMR as one of the top 10 priorities for the ministry’s collaborative work with WHO for 2018-19.

• In 2012, India’s medical societies adopted the Chennai Declaration, a set of national recommendations to promote antibiotic stewardship.
• India’s Red Line campaign demands that prescription-only antibiotics be marked with a red line, to discourage the over-the-counter sale of antibiotics.
• National Policy for Containment of Antimicrobial Resistance 2011.
• National Action Plan on AMR resistance 2017-2021.
• In March 2014 a separate Schedule H-1 was incorporated in Drug and Cosmetic rules to regulate the sale of antimicrobials in the country.
• The government has also capped the maximum levels of drugs that can be used for growth promotion in meat and meat products.

 

Escherichia coli (E. coli):  This bacterium is a common cause of food-borne disease and urinary tract infections. The rate of antibiotic resistance in E. coli is increasing quickly.