Bitter pill to swallow
- Rampant use of antibiotics in humans and food animals is leading to the development of drug-resistant bacteria
Jun 30, 2014-
Alexander Fleming’s discovery of penicillin in 1928 heralded a new era of medicine in the world. A chemical that could control bacterial infection, penicillin saved more lives during World War II than would have been possible. Suddenly, cases of people dying from simple wound infections were a thing of the past and lives were being saved on a daily basis. Since then, new drug discoveries have resulted in various types of antibiotics being used in medicine around the globe. During the 1940s, when penicillin was finally commercially used as a drug, no one would have guessed that there would come a time when this and other newer antibiotic discoveries would slowly start becoming less effective.
Antibiotic resistance is a phenomenon whereby bacteria are able to withstand the negative effects of an antibiotic, which previously would have killed them at similar concentrations. To make it simpler, bacteria that are resistant to a given antibiotic will not be affected by a normal dose of that particular antibiotic. Thus, a medical practitioner will have to recommend a higher dose of the same antibiotic to cure infection caused by a resistant bacteria. With time, even the higher dose starts become less and less effective, eventually making the dose either completely useless or too dangerous for the patient to consume.
Another risk that the use of antibiotics poses is a threat to otherwise harmless and even useful bacteria that reside in our body. Our gastrointestinal system (digestive system) is full of such bacteria, without which the food we eat cannot be digested; thus, all the nutrients that we derive from our food is courtesy of those bacteria. When we consume antibiotics, even these bacteria are killed since they are also affected by antibiotics. When we take higher dosage of antibiotics, we stand to lose more of these bacteria, something that should be avoided at all costs.
Antibiotic resistance is an issue medical scientists had already begun discussing a long time ago. The discussion started when antibiotics started to lose their effectiveness in developed countries, especially in nosocomial (hospital borne) infections. The trend since then has only increased in developed nations, and in the last decade or so, started being observed in developing countries also. Notably, the recent discovery of the NDM-1 gene (or New Delhi Metallo Beta Lactamase 1 gene) in some bacterial strains capable of causing infections in human has led to speculations that antibiotic resistance is very much established in this region of the world. The NDM-1 gene confers resistance to most common antibiotics currently used worldwide. Thus, bacteria containing this gene are at an advantage and are very dangerous to humans. There are already reports of a number of disease-causing bacterial strains carrying this gene in India, Pakistan and Nepal.
The most important cause for the development of antibiotic resistance in bacteria is over-exposure to a particular antibiotic, thereby allowing the bacteria to build its defences against the chemical. This is possible due to the ability of the bacteria to activate certain proteins that minimise the effects of the antibiotic upon overexposure. This, in turn, is regulated by certain genes in the bacterial genome. Thus, when we talk of NDM-1 bacteria, we are talking about bacteria that have turned on that particular gene (NDM-1) which allows them to counter most antibiotic types.
Genes can be transferred from one bacteria to another in two major mechanisms (although there are other possibilities also). A common type is due to bacterial division whereby ‘parent’ bacterial genomes are replicated to ‘clone’ bacterial cells (referred to in scientific literature as vertical transmission). Not so common, but very possible is ‘horizontal transmission’ whereby genes ‘jump’ into otherwise non- or less resistant bacteria in the vicinity. This type of transmission can then infect an entire colony of bacteria, which can then infect other bacteria or pass on the resistant gene to their clones.
A major problem
Is antibiotic resistance a cause for concern? The answer is a straightforward ‘yes’. Although numbers vary, the US’ Center for Disease Control (CDC) report of 2013 states that in the United States alone, over 2 million people were infected with antibiotic resistant bacteria and at least 23,000 deaths were linked to antibiotic resistance. Most cases were linked to hospital infections. Similarly, in Europe, a report published by European Centre for Disease Prevention and Control (ECDPC) in 2013 clearly states that antibiotic resistance poses a serious risk to public health in Europe in terms of treatment failures and even death. In South Asia, the escalating problem of antibiotic resistance was reported recently in a 2014 World Health Organization report on global antibiotic resistance. The WHO office for the South East Asia region (SEARO), of which Nepal is a member country, recently issued a press release stating the antibiotic resistance is now an established problem in all parts of the globe. All this evidence points to the growing threat of antibiotic resistance becoming a major public health problem worldwide.
Antibiotic use in the food animals sector is another major problem, which is now being seen as a threat to antibiotic resistance. Prophylactic (meaning before actual infection) use of antibiotics in poultry, cattle, pigs, fish and even seafood is now widely accepted to be the cause of the emergence of antibiotic resistant bacteria in those animals, fish and seafood, which can be transferred to humans in case of unhygienic consumption. Therefore, there is a worldwide drive to control such use of antibiotics in food animals. In Nepal also, the poultry sector is known to use the same antibiotics that are used for humans without a control mechanism in place. Thus, there remains an imminent risk of antibiotic resistance in poultry pathogens, which can then be a risk for the human population.
Controlling antibiotic resistance should start with the controlled use of antibiotics in the human and veterinary sector. Rampant prescription of antibiotics by clinicians, even when they may not be required, is an area where focus is needed. Over the counter sale of antibiotics, which is rampant in many developing countries including Nepal, needs to be stopped. Even the general population needs to understand the dangers of consuming antibiotics, especially by children without proper consultation with their physicians.
Antibiotic resistance is a present danger and can turn into a pandemic if urgent steps are not taken immediately. One of Darwin’s postulates applies very well in this context—“Individuals with the most favourable adaptations are more likely to survive and reproduce.” In the context of antibiotic resistance, bacteria that can express their genetic elements to counter antibiotics are more likely to survive than those that cannot and evidence suggests that this process has already started. The fast rate of bacterial division and the amazing ability they possess to mutate to ensure survival are two of the biggest reasons why antibiotic resistance is going to continue to become an even bigger threat in the future, if immediate steps are not taken. The world needs to reverse this trend and do it fast. The first step is for us to understand and accept this problem. Once we do that, the process will have started.
Dixit is Director of Research at the Center for Molecular Dynamics Nepal and Principle Investigator at Global Antibiotic Resistance Partnership Nepal
Published: 01-07-2014 09:09