FACTORS THAT CONTRIBUTE TO ANTIBIOTIC (ANTIMICROBIAL) RESISTANCE

Antibiotic resistance is a global health problem that bedevils our health sector and threatens our ability to effectively treat some infectious diseases. Antimicrobial resistance is the ability of microbes to grow in the presence of a chemical agent or drug that would normally kill it or limit its growth. Antibiotic resistance can spread to humans from human-to-human contact, from raw food, and from the environment.

Antibiotic or antimicrobial resistance is a natural process of microbial adaption that leads to a limited lifespan of some available antibiotics. And the simpler reason there is for the emergence and spread of antibiotic resistant strains of microbes is largely attributable to the unnecessary and inappropriate use of antibiotics. The uncontrolled usage of antibiotics (especially those meant for human medicine) in animal husbandry, poultry production and in other veterinary and agricultural practices has skyrocketed the problem.

The global problem of antibiotic resistance has been compounded not only by microorganisms that are resistant to only one antibiotic. Rather, the rise and spread of multi-drug resistant microorganisms including but not limited to methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-intermediate Staphylococcus aureus (VISA), vancomycin-resistant Staphylococcus aureus (VRSA), extended spectrum beta-lactamase (ESBL) – producing bacteria, vancomycin-resistant Enterococcus (VRE) and metallo-beta-lactamase (MBL) positive bacteria. It is therefore vital to conserve the available antibiotics and/or antimicrobial agents we have left by using them optimally.

Antimicrobial stewardship is therefore defined as the judicial or rational use of available antimicrobial agents in such a manner that limits the emergence and spread of drug-resistant pathogens. Novel antimicrobial agents and/or antibiotics should be developed to contain the excesses of drug-resistant microbes, and novel technologies for the prompt diagnosis and treatment of infectious diseases should also be developed to avoid delay in treatment.

A great many factors contribute to the antibiotic resistance that we now face in both the community and in the hospital environment. Most of these factors have to do with both human behavior and activities while the other factors are contributed by the microbes themselves. The first among these factors that contribute to the development of antibiotic resistance is “natural selection”, a natural process of microbial adaptation. Microbes, over time, are capable of adapting in ways which increases their ability to survive in a changing environment – including environments with potent antimicrobial activity.

Studies have shown that the bacterial genomes represent a large natural pool of diverse genetic information that can be accessed under appropriate selection pressures, using a variety of gene acquisition and dissemination mechanisms. Human application of toxic agents such as antibiotics that have cidal or growth-inhibitory effects on microbes on massive scale activates these genetic systems to promote survival of the microbial population in the face of the toxic agent.

As a result, each and every antibiotic will have a finite lifetime depending on the magnitude and nature of its use; and thus the development of antibiotic resistance in such scenarios is inevitable. As pathogens encounter large amounts of antibiotics, those that have little or no resistance to the antimicrobial agent are killed off en masse first, while on the other hand, those that already possess some measure of resistance due to previous encounters with the drug or random mutation in their genome, have a much higher likelihood of survival.

Once the weaker bacteria have been destroyed by the antibiotics, the remaining resistant organisms will continue to thrive. Though the process of natural selection takes generations to occur, but in bacteria, those generations are produced in a matter of hours or days rather than years or decades in other organisms. Some of the notable contributing factors to the development of antibiotic resistance in bacteria are highlighted as follows:

• Overuse of antimicrobial agents (antibiotics) especially unwisely.

• Excessive use of antibiotics in livestock and animal feeds.

• Use of antibiotics as growth promoting agents in livestock production.

• Poor patient compliance towards drug regimens.

• Self-medication that defies a doctor’s prescription.

• Poor personal hygiene.

• Poor infection control practices in our hospitals.

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