A Global Village
Issue 4 » New Frontiers in Health

Antimicrobial Resistance

Overcoming this Emerging Threat

Sameer Bahal, Imperial College London

Antimicrobial agents have been around for less than 100 years, however, they have revolutionised the treatment of infectious diseases. The mortality of many of these diseases has declined dramatically and the development of such drugs has been heralded as a major advance in medicine.

Unfortunately, an increase in antimicrobial resistance has meant that some of the medications that we use today are becoming less effective and many countries are now seeing an increase in the number of infections with resistant organisms such as Methicillin-resistant Staphylococcus aureus and Multi-drug-resistant TB. The WHO estimates that 440,000 cases of Multi-drug-resistant TB emerge each year causing roughly 150,000 deaths.

Recently antimicrobial resistance has been in the news after the Lancet published a paper showing that bacteria with the antimicrobial resistance gene NDM-1 have been found in the water supply in Delhi. This enzyme destroys carbapenems, a group of antibiotics used to treat difficult infections. The Health Protection Agency (HPA), which has monitored antimicrobial resistance for 30 years, has said it recorded 88 cases of bacteria with NDM-1 (New Delhi Meallo-beta-lactamose) in the UK. Most of the patients had been linked to India. This development is worrying news for governments and may prompt an increased focus on antimicrobial resistance. 

Some doctors are predicting that
in a few decades some easily
treatable diseases will become
impossible to treat. Among these
include Tuberculosis and Malaria.

Drug resistance causes harm and possible death to patients. Pathogens that are drug resistant are much harder to treat and so patients generally spend more time in hospital meaning that they are more likely to spread their infection to others. They are also likely to need more drugs that may have adverse side effects, leading to additional suffering for both the patient and their family. These factors also lead to an associated increase in the cost of healthcare; for example, patients with a drug resistant infection are often unaffected by oral medication and so need intravenous drugs, which are more expensive and have further costs associated with their use. Whilst this increased cost is a manageable issue in the UK, it can cause greater difficulties in developing countries, particularly as infectious diseases are often more prevalent in these regions.

If drug resistance is not tackled comprehensively, the long-term implications will greatly affect healthcare in the future. Already some doctors are predicting that in a few decades some easily treatable diseases will become impossible to treat. Among these include Tuberculosis and Malaria. Even now, in some cases, doctors skip first line medications and go straight to costlier second line ones as they presume resistance.

In order to tackle this global problem, countries need to make a collaborative effort to combat this resistance, as antimicrobial resistance does not respect borders. Indeed, recently the WHO declared antimicrobial resistance the theme for World Health Day 2011. Solutions outlined include preventing the spread of infections, developing new medications and improving regulation of those currently in use. 

The genes for antibiotic resistance develop and persist primarily due to the overuse of antibiotics. Generally, the greater the exposure to these drugs, the faster resistance develops. Antibiotic misuse must therefore be addressed in humans and in animals.

Misuse in Humans
In the USA in 1998, 80 million prescriptions for antibiotics were filled. In a lot of these cases patients did not actually have an infection that would have been helped by antibiotics. This overuse is due to both doctors and patients: increasingly well informed patients may demand antibiotics even when their medical condition does not warrant it. In addition, doctors are more willing to agree to patient demands due to a risk of litigation. In other words, doctors often act to minimise any risk of complaint even if it means exposing a patient to unnecessary medication. Examples of diseases that are over treated with antibiotics include colds and flus. In the UK doctors are unlikely to prescribe medication in these cases unless there are serious underlying medical conditions. However, in countries with less regulated health care systems, such as India, doctors are more likely to prescribe. In these cases, patients may wrongly believe that their doctor is taking their condition more seriously, whereas in fact this is not the reality. 

Doctors often act to minimise
any risk of complaint even if
it means exposing a patient
to unnecessary medication

Another area of concern is compliance. When doctors prescribe antibiotics, it is usually for a course that must be taken over a set period. It is important that patients take the whole course to ensure that the infection is completely treated. There is a big risk of patients stopping their medicine intake after a few days, when they are feeling better, but the antibiotic course has not been completed. This can lead to partially treated infections, and importantly, the pathogen has had enough exposure to an antimicrobial to develop resistance, but not enough for it to be killed. It is therefore integral to educate people of the need to complete antibiotic courses to stop the development of resistance.

Misuse in Farming
Agricultural practices account for about 60% of antimicrobial use in America. This is equivalent to about 18,000 tonnes per year. Irresponsible use of antibiotics in farm animals is an important cause of bacterial resistance. Bacteria living in animals will develop resistance and can then pass it on to human bacteria. Importantly, antibiotics are used as feed additives to farm animals. This is to prevent rather than treat infection. Many health care professionals consider this an irresponsible use of the drugs. 

In many countries, treatment of animals is poorly regulated. In the USA one study suggested that 90% of all veterinary drugs are administered without a professional veterinary consultation. It can also be the case that medications can be acquired without a prescription. Often inappropriate doses and combinations of medications are used. 

Diagnosis is also a problem. Due to modern intensive farming methods, farmers are pressured into keeping costs as low as possible and it has been reported that farmers will often not properly diagnose an illness, preferring to give antibiotics straight away, as laboratory tests are too expensive.

Some farmers argue that antibiotics
will keep livestock healthy and
hence reduce the incidence of
infections in humans who eat meat

However, some farmers argue that antibiotics will keep livestock healthy and hence reduce the incidence of infections in humans who eat meat. This argument emphasises the importance of education for farmers about resistance, as well as the need for new regulations that are based on firm scientific fact to be bought into practice. 

New Antimicrobial Development
New medications are being developed continuously, but most of these are for medical conditions such as Hypertension. Over the last decade or so there have been relatively few new antimicrobials. This is because antimicrobial drugs need to be toxic to pathogens, but not to human cells; this means that they must target sites that are unique to pathogens. There are relatively few suitable sites and hence drug development has been slow. 

A key impediment is that drug development is an expensive process. Today a new drug will usually cost about a billion dollars to develop and test. Drugs usually go through many stages of testing and clinical trials to determine their side effects and efficacy. It therefore often takes several years before a medication is available for general use in hospitals. New drug development is often funded by the drug company’s themselves; however, they may ignore research into antimicrobials as other therapeutic goals may be more lucrative. Therefore, extra funding from governments, specifically targeted at the development of antimicrobials is vital. 

The WHO has recently released a six-point policy for antimicrobial resistance. Firstly, the global community must try to prevent infections in patients. This will involve improving hygiene and increasing the availability of vaccines. Furthermore, surveillance of resistance, coupled to increased laboratory capacity, is crucial. 

 

In addition, it is widely accepted that reducing the use of currently available antimicrobials is very important. This means a combined effort from the farming industry and the healthcare sector is needed. Finally, countries need to invest in the development of new drugs. While this will prove expensive and time consuming, the alternative of widespread antimicrobial resistance will be far worse. 

The impact of antimicrobials in modern medicine has been unquestionable. However, if they are to remain an effective treatment for infections, action must be taken to reduce antimicrobial resistance. The WHO is leading the response to antimicrobial resistance by providing policy guidance, technical assistance and working to prevent the spread of infectious diseases. Singular interventions will have little impact, so the global community must work together in pursuit of this goal. 


Sameer Bahal is a final year medical student at Imperial College London and has been actively involved in the Imperial College Model United Nations society for several years.

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