In the developing world, human activities are a major cause that disturbs the natural state of the environment and other organisms, causing them to either perish or become more dangerous than before. Antimicrobial resistance often referred to as AMR is now increasingly viewed as a global health hazard by the WHO because of its serious nature. It has been observed that the ever-increasing usage of medicines like antimicrobials has been aggravating the issue further. Hence studying about this becomes important.
Antimicrobial is a wide term that includes antibiotics, antivirals, etc. and is a group of medicines used to cure infections in human beings, animals, and plants of concern
AMR tends to appear when these organisms (bacteria, viruses, etc.) show changes in their structure or physiology which makes them immune to medicines. This leads to the medicines being ineffective and the infections, being harder to treat leading to the possibilities of increased spread of disease, and death rates
In this section, we will look at some examples of the various types of microorganisms-
Drug resistance in bacteria
Ciprofloxacin was an antibiotic that served to cure infections of the urinary tract. In a study done worldwide, the rate of resistance to this drug ranged from 8% to 93% for E. coli indicating the increasing resistance to the given drug.
Gonorrhoea, a sexually transmitted disease has been difficult to manage in recent times due to the resistance shown by the highly variable strains of N. gonorrhoeae.
Drug resistance in viruses
Immuno-compromised patients are the ones who are deeply affected by the emergence of this condition. This mainly occurs due to the selection of resistant strains of the virus to prolonged exposure to the drug and rapid viral replication leading to faster mutations. It has been found that resistance has been formed in most antivirals
The emergence of the new drug−resistant strain of HIV has increased the risk of antiretroviral drugs becoming ineffective
Drug resistance in fung
The drug−resistant strain of Candida auris that causes one of the most prevalent and invasive fungal infections has been more widespread than ever before since it has reported resistance to drugs like amphotericin B etc
It can be classified according to their mechanisms in organisms and are of the following four types
Limiting uptake of drugs
Gram−negative bacteria have the presence of lipopolysaccharides whose structure acts as a barrier against foreign molecules giving them an inbuilt resistance to various types of antimicrobial drugs
Organisms like Mycoplasma lack a cell wall and hence are protected from drugs that attack the cell wall of organisms
Mutations such as creating a thicker cell wall or formation of a biofilm−like substance protect the bacteria from microbial agents as well.
Modification of drug targets
Drugs is generally designed in a manner that they could only attack a specific target component in the cell of the microorganism. Hence modification of the target component by the organism renders the drug useless
Drug inactivation
Drugs may be inactivated by the microorganism through 2 main pathways− the first that involves the actual degradation of the drug and the second that involves the transfer of a different chemical compound to the drug
Examples of the first pathway include the beta−lactamases which are a group of enzymes that are capable of hydrolysing the drugs.
Transfer of a chemical compound to the drug usually involves the transfer of groups like acetyl, and phosphoryl groups to the drug which bind and disables the antimicrobial properties of the drug
Drug efflux
Microorganisms have been studied and certain genes responsible for the presence of efflux pumps have been observed which are chromosomally encoded. They may be present constitutively or be overexpressed (mainly due to a mutation) under certain environmental conditions. The main function of these efflux pumps is that they help the cell to remove harmful substances. One of the important properties of these pumps is that they can transport a variety of compounds and are hence referred to as Multi−Drug Efflux Pumps.
| Antibiotic resistance | Antimicrobial resistance |
|---|---|
| It includes drugs that prevent and cure infections caused by bacteria. | It is a broader term that encompasses resistance shown by other organisms as well such as viruses, fungi etc |
| Examples include Penicillin, Tetracyclines etc | Examples include Fluconazole, Valacyclovir |
A few causes of antimicrobial resistance can be summarised below−
Unregulated and overuse of antibiotics is the primary cause of AMR. The use of antimicrobial drugs for the simplest of clinical problems like the common cold has given over exposure to microorganisms, allowing them to mutate at a much faster pace than before leading to the selection of drug−resistant strains
The use of drugs in agricultural practices provides new passage for drug−resistant microorganisms to enter the human body and cause maladies
According to statistical reports from surveys, lakhs of people are said to lose their lives due to complications caused by AMR and this number is likely to increase in the coming years. Countries are facing major challenges to fight diseases like tuberculosis, dengue, AIDS, etc which are becoming difficult to treat as their drug−resistant forms are emerging. Hence the study and research on antimicrobial resistance becomes eminent. Through this article, we understand the concept of AMR and look at its various types supported by various examples. We look at some major causes and try to clear out a common confusion− the difference between antibiotic resistance and antimicrobial resistance
Q1. What is a mutation?
Ans. It can be referred to as an alteration in the nucleotide sequence in the DNA of any living organism. It mainly occurs due to the accumulation of various variations due to sexual reproduction and evolution or may be due to any external factors like exposure to radiation etc. The mutations are permanent and are passed on to the descendants of that particular mutated cell.
Q2. What is an infection?
Ans. In simple terms, it can be referred to as the invasion and growth of foreign organisms in the host body which causes harm and health problems. Foreign organisms, often referred to as pathogens include a variety of microorganisms like bacteria, viruses, protozoans, etc.
Q3. How can AMR be avoided?
Ans. First and foremost, the overuse of drugs should be avoided. For this, the World Health Organisation has published a set of guidelines on how each drug should be used and in how much quantity. Usage of anti−microbial as growth inducers in livestock and crops should strictly be avoided. As we all know, prevention is better than cure. Hence, better hygiene, and good access to water, food, and healthcare facilities should be upgraded to reduce health problems in the population and ultimately lead to less use of drugs. Vaccines and alternative therapeutic techniques should be explored to minimize the usage of drugs.
Q4. What are the examples of common drug−resistant microorganisms?
Ans. The most common example is multi−drug resistant Mycobacterium tuberculosis (MDR−TB). TB, if caused by this organism is not curable. Other examples include vancomycin-resistant Enterococcus (VRE) and methicillin-resistant Staphylococcus aureus (MRSA).
Q5. What are the target sites of antimicrobial drugs?
Ans. The most common cellular targets for any antimicrobial drug include disrupting the cell wall synthesis, silencing the DNA gyrase, and interrupting the action of cellular enzymes and protein synthesis.
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