Why only some bacteria develop multi-drug resistance?

Context:

A recent study subjected E. coli to fluctuating and steady environments, noting their evolutionary response in order to understand why some bacteria evolve multi-drug resistance while others do not.

Relevance:

GS-III: Science and Technology

Dimensions of the Article:

1. What is Antimicrobial Resistance (AMR)?
2. What is Multi drug resistance?
3. Findings of the recent study on MDR
4. Concerns regarding Antimicrobial resistance (AMR)

What is Antimicrobial Resistance (AMR)?

• Antimicrobial resistance (AMR) is the ability of microorganisms such as bacteria, fungi, viruses, and parasites to remain unaffected or survive antimicrobial drugs such as antibiotics, antivirals and antimalarials.
• AMR occurs when microorganisms exposed to antimicrobial drugs develop antimicrobial resistance resulting in standard treatments becoming ineffective leading to persistence of infections and spreading of infections.
• Microorganisms that develop antimicrobial resistance are sometimes referred to as “superbugs”.
• The misuse of antimicrobials in medicine and inappropriate use in agriculture is one of the major causes of spread of Antimicrobial Resistance.
• Contamination around pharmaceutical manufacturing sites where untreated waste releases large amounts of active antimicrobials into the environment also leads to spread of AMR.

What is Multi drug resistance?

• Multiple drug resistance (MDR), multidrug resistance or multi-resistance is antimicrobial resistance shown by a species of microorganism to multiple antimicrobial drugs.
• The types most threatening to public health are MDR bacteria that resist multiple antibiotics; other types include MDR viruses, parasites (resistant to multiple antifungals, antiviral, and antiparasitic drugs of a wide chemical variety).
• Recognizing different degrees of MDR, the terms extensively drug resistant (XDR) and pandrug-resistant (PDR) have been introduced.

Basis of Antimicrobial Resistance

• Some bacteria due to the presence of resistance genes are intrinsically resistant and therefore survive on being exposed to antibiotics.
• Bacteria can also acquire resistance by sharing and transferring resistance genes present in the rest of the population, or by genetic mutations that help the bacteria survive antibiotic exposure.

Findings of the recent study on MDR

• 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.
• When bacteria become fit in one environment, they either lose fitness or fail to increase fitness in other environments – this study shows that when the environment is fluctuating, large (but not small) populations can by-pass this effect.
• The study found that small populations acquire a certain set of mutations which 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. All else being equal, whether the bacteria pay fitness costs or not will depend on the population size they evolve in.

Concerns regarding Antimicrobial resistance (AMR)

• Medical procedures such as organ transplantation, cancer chemotherapy, diabetes management and major surgery (for example, caesarean sections or hip replacements) become very risky due to AMR.
• AMR increases the cost of healthcare with lengthier stays in hospitals, additional tests and use of more expensive drugs.
• No new classes of antibiotics have made it to the market in the last three decades, largely on account of inadequate incentives for their development and production.
• Without urgent action, we are heading towards a future without antibiotics and with bacteria becoming completely resistant to treatment and when common infections and minor injuries could once again kill (referred to as antibiotic apocalypse).
• It is putting the gains of the Millennium Development Goals at risk and endangers achievement of the Sustainable Development Goals.

Concerns regarding AMR in India

• India, with its combination of large population, rising incomes that facilitate purchase of antibiotics, high burden of infectious diseases and easy over-the-counter access to antibiotics, is an important locus for the generation of resistance genes.
• The multi-drug resistance determinant, New Delhi Metallo-beta-lactamase-1 (NDM-1), emerged from this region to spread globally – Africa, Europe and other parts of Asia have also been affected by multi-drug resistant typhoid originating from South Asia.
• In India, over 56,000 newborn deaths each year due to sepsis are caused by organisms that are resistant to first line antibiotics.

-Source: The Hindu