The word ‘antibiotic’ is commonly understood to mean medicine that is destructive to bacteria. The word ‘biotic’, however, derives from the Greek biotikos, which means ‘fit for life’. That may be the cruel twist in the tale of these modern-day wonder drugs, that they are no longer on our side in the struggle of life.
Sir Alexander Fleming discovered the first antibiotic, penicillin, in 1928. Since then, different antibiotic groups have been discovered which have successfully helped to treat bacterial infections and saved millions of lives.
Since then, severe overuse and abuse of antibiotics has been the prominent feature of their use by humans. Overuse of antibiotics in plants and livestock animals has also increased its concentrations in humans via the food chain. It has been overused in diseases as simple as cold and cough in humans and in crops and livestock for prevention instead of cure. Consequently, the effectiveness of this class of drugs has slowly diminished, resulting in the phenomenon of antibiotic resistance, or AR, the ability of bacteria to evade the action of an antibiotic. In other words, the antibiotic can no longer kill the bacteria, which can now continue to cause prolonged inflammation in our body that can be fatal at times.
Bacteria evolve different mechanisms to become resistant to antibiotics. One of the common methods by which bacteria evade the action of antibiotics is by natural selection of their mutant variants. For example, let’s consider an antibiotic ‘A’ that can kill all the strains of bacteria ‘B’. As ‘B’ is continuously exposed to higher concentrations of ‘A’ (human, crops and livestock worldwide combined together), random mutations can occur in its genes that can help it to evade the actions of ‘A’. If there is even one bacterium that has undergone mutation, it can multiply rapidly and replace all the strains that were sensitive to the antibiotic ‘A’. This is known as selection pressure and in this case, the selection has resulted from increased exposure to antibiotics. Thus, the new strain of bacteria ‘B’ is now resistant to the antibiotic ‘A’.
Some of the other techniques used by bacteria include: pumping antibiotics out via membrane transporters, and preventing antibiotics from attaching to the bacteria by changing the outer membrane structure.
AR is a subset of Antimicrobial Resistance (AMR), where a microbe (bacteria, virus, fungi or protozoa) is resistant and can evade the effects of antimicrobials. It is difficult to treat AR bacteria as they are also resistant to higher doses of antimicrobials. In many cases, this leads to toxicity in patients.
Based on the extent of resistance to multiple antibiotics, bacteria can be classified as multidrug-resistant (MDR, if it is resistant to more than one antibiotic), extensively drug-resistant (XDR, if it is not resistant to only one or two antibiotics) or totally drug resistant (TDR, if it is resistant to all the available antibiotics). XDR and TDR bacteria are often referred to as ‘superbugs’.
The implications of AR are severe. It can result in going back to the pre-antibiotic era where millions of people died from simple bacterial infections. It can severely affect patients with something as minor as a stomach or tooth infection to those in post-surgery recovery. Simple infections like food and water-borne diseases—gonorrhea, pneumonia, etc.— will again become life threatening.
The Centers for Disease Control (CDC), leading public health institute of the US, estimates that every one in 25 patients around the globe will acquire an infection due to their hospital stay. By 2050, the expected number of deaths due to antibiotic resistance is predicted to be 10 million. According to CDC, at least, two million people are infected with AR bacteria in the US alone, and about 23,000 die from the infections. About 750,000 people die every year worldwide due to infections by AR bacteria. If countries do not take strict actions, AR will further limit the scope of modern medicine.
India is one of the biggest hubs in the world for development of AR bacteria. This is directly related to the excessive overuse and abuse of antibiotics in human as well as in crops and livestock, over-the-counter prescription, improper hospital conditions and poor sanitary conditions. In India, XDR and TDR superbugs of some of the human commensal bacteria have been identified. One of them identified even worldwide is the multidrug resistant Staphylococcus aureus. Recently, a new superbug variant of Klebsiella pneumoniae has also been identified in India.
It is easy to treat the non-AR strains of these bacteria, but inability to treat the AR variant will result in fatal consequences. In the book, The Perfect Predator: A Scientist’s Race To Save Her Husband From A Deadly Superbug: A Memoir, Steffanie A. Strathdee recounts how a simple food poisoning almost took the life of her husband.
In order to fight antibiotic resistance, every country must have a strong national policy to lay down strict healthcare regulations. Unfortunately, in India, the guidelines are not strictly followed. This is also due to lack public of awareness.
The government must invest more in healthcare infrastructure and increase social awareness. At the same time there is a need for developing new antibiotics. We must also urgently focus on developing vaccines, which will ensure the best way to eradicate infections without the complications of resistance. Or we’re just heading back into a dark and deathly age.
Sanchari Banerjee is post-doctoral researcher with interest in protein crystallography
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