What Are MDR Bacteria and Why Are They a Threat?

Multi-drug resistant (MDR) bacteria are microorganisms that have developed the ability to withstand the effects of multiple antibiotic classes, making infections they cause difficult or impossible to treat with conventional medications. This resistance poses a significant public health concern because it limits treatment options, leading to prolonged illnesses and more severe outcomes.

How Bacteria Develop Multi-Drug Resistance

Bacteria primarily develop multi-drug resistance through evolutionary processes, like natural selection and the acquisition of resistance genes. When exposed to antibiotics, susceptible bacteria are eliminated, allowing resistant strains with pre-existing mechanisms to survive and multiply, increasing their prevalence.

Resistance genes can arise from spontaneous mutations in a bacterium’s genetic material. These mutations can alter bacterial structures or processes, such as modifying the antibiotic’s target site or enabling them to pump the antibiotic out. Some mutations can even affect genes involved in cellular metabolism, indirectly leading to resistance.

Bacteria also acquire resistance genes through horizontal gene transfer, where genetic material is shared between bacteria. Plasmids, small circular pieces of DNA, are key vehicles for this transfer, carrying resistance genes that can be passed between different bacterial species through direct contact in a process called conjugation. The misuse and overuse of antibiotics accelerate these natural processes by creating selective pressure that favors resistant strains.

Common Environments for Multi-Drug Resistant Bacteria

Multi-drug resistant bacteria are commonly found in several environments. Healthcare facilities, such as hospitals and long-term care facilities, are reservoirs where these bacteria thrive and transmit. Patients who are older, severely ill, or have underlying conditions are particularly susceptible to infections in these settings.

Agricultural settings also contribute to the prevalence of resistant bacteria due to the use of antibiotics in livestock. This practice can lead to resistant strains entering the food chain or environment. Beyond healthcare and agriculture, MDR bacteria are increasingly found in community settings, spreading through person-to-person contact.

Transmission occurs through direct contact with an infected person or their bodily fluids, or with contaminated surfaces or medical equipment. Hand hygiene is a primary method to prevent their spread. The movement of animals can also contribute to the spread of resistant bacteria.

Understanding the Health Impact

Infections caused by multi-drug resistant bacteria challenge individual and public health systems. When antibiotics are ineffective, infections become harder or impossible to treat, leading to prolonged illnesses, extended hospital stays, and a greater risk of adverse health outcomes.

These consequences include increased healthcare costs for individuals and the broader economy. Treating resistant infections cost significantly more, with estimates suggesting an increase of around 700 US dollars per case, and novel treatments potentially costing tens of thousands. Globally, the economic cost of antimicrobial resistance was estimated at US$693 billion in 2019, with projections of up to US$1.7 trillion in global economic losses by 2050.

Rising resistance rates also impact the safety and efficacy of routine medical procedures that rely on effective antibiotics for infection prevention. Surgeries, organ transplants, and cancer chemotherapy become riskier when prophylactic antibiotics are less effective. A 30% reduction in antibiotic efficacy could result in 120,000 additional surgical site infections and post-chemotherapy infections per year in the USA, alongside 6,300 additional infection-related deaths.

Global Efforts Against Multi-Drug Resistance

Addressing multi-drug resistance requires a coordinated global approach. One strategy involves promoting responsible antibiotic use through “antibiotic stewardship” programs. This optimizes antimicrobial medicine use in human and animal health, ensuring they are prescribed and used only when necessary and appropriately.

Infection prevention and control measures also limit the spread of resistant bacteria. Practices like rigorous hand hygiene, environmental cleaning, and appropriate waste management are implemented in healthcare facilities and communities. Preventing infections reduces the need for antibiotics, thereby curbing resistance development.

Research and development efforts focus on discovering new antibiotics, alternative treatments, and rapid diagnostic tools. Accelerating the pipeline of new drugs is needed to combat emerging resistance. Global surveillance systems, like the Global Antimicrobial Resistance and Use Surveillance System (GLASS), monitor resistance patterns and antibiotic consumption worldwide. These systems provide data to inform public health policies and interventions. The World Health Assembly adopted a global action plan on antimicrobial resistance in 2015, outlining objectives to improve awareness, strengthen knowledge through surveillance, reduce infection incidence, optimize antibiotic use, and ensure sustainable investment.

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