Currently, AMR is responsible for 700,000 deaths worldwide; while this number is shocking enough already, by 2050 the AMR Review 2016 predicts that drug resistant infections will kill around 10 million.
There are four main mechanisms for bacteria to develop antibiotic resistance: inactivation, alteration of the target, circumvention of the target pathway, and efflux of the antibiotic. Additionally, resistance can be developed through the mutation of existing genes, known as vertical evolution (Crumplin and Odell, 1987)( Martinez and Baquero, 2000), or by horizontal gene transfer, in which the bacteria acquires new genes from other bacteria strains or species (Palmer et al., 2010) (Hegstad et al., 2010) (McManus, 1997).
Horizontal gene transfer can occur by a variety of different mechanisms. Mobile genetic elements, which includes phages, plasmids, and transposons, facilitate the transfer. In some cases, low levels of the antibiotic in the environment is a critical indicator that encourages gene transfer (Jeters et al., 2009) (MedScape).
Inappropriate antibiotic prescriptions
Each year millions of antibiotics are erroneously prescribed; this rampant, inappropriate usage of antibiotics is a key cause of resistance spread (NICE, 2015). Inappropriate prescribing occurs when:
- The prescribed antimicrobial drug has been proven inefficient for treatment (e.g. in cases where infection is caused by a microbe that is not sensitive to the prescribed drug)
- A diagnostic test that could have shown the source of infection was not bacterial is not used
- Second or third line antibiotics are prescribed when a first line drug would have been an effective treatment (AMR Review, 2016)
- A diagnosis is made based entirely off patient symptoms without a rapid diagnostic test wherein the similar symptoms shared by bacterial and viral infections can make accurate assessment tricky
- Antibiotics are prescribed because they are cheaper than available diagnostic tests (AMR Review, 2016)
As standard treatments grow increasingly ineffective, infections are becoming more difficult or even impossible to control which presents a grave threat of infections spreading. The risk of fatality increases when combined with the fact that, with the spread of resistance, illnesses and hospital stays will now be prolonged (WHO, 2014). Information on over-the-counter antibiotic sales are difficult to obtain in many countries and in those where data is available, information is often inconsistent. In the EU, the European Union Council has recommended that antibiotics should be used as prescription only medicines in member states (2002/77/EC); despite this, some areas in Southern and Eastern Europe consume between 20% and 30% of antibiotics without a prescription (Morgan et al., 2011) (AMR Review, 2016).
Antimicrobial Resistance in Hospitals
Hospitals are the main hubs for the development of antimicrobial resistant agents, particularly of the ones critical for human health. Therefore, the control and prevention of healthcare-associated infections (HAIs) plays a crucial role in the effort to contain the spread of multidrug-resistant bacteria within and outside of healthcare environments. However, at the EU level, for example, it is still not legally binding that all EU member states report on the level of resistant infections at the national level through the European Antimicrobial Resistance Surveillance Network (EARS-Net). It is critically important that hospitals have HAI surveillance systems and infection control committees in place to be able to cope with AMR challenges.
While the healthcare sector is often assumed to be the largest source of pharmaceuticals in wastewater, in reality they account for less than 10% by weight (Kümmerer, 2009) (Korzeniewska et al., 2013). The main culprits of the large quantities of pharmaceuticals in municipal wastewater are poor community disposal practices and the excretion of drugs. Aside from pharmaceutical waste, improper disposal of infectious waste from the healthcare sector is a notable source of the spread of antibiotic resistant bacteria.
Within hospitals and healthcare systems, the food they choose to buy and serve plays an important role in guiding global action that protects public health, the environment, and the economy. Several food ingredients contribute to AMR through their production, processing, and preparation; despite this, the use of antibiotics in food production has largely been unrecognised and pushed aside in favour of other factors influencing AMR.
When an infection has not responded to other drugs, last resort antibiotics may come into play; the frequent use of these last resort drugs in livestock can rapidly increase the threat of AMR and impact our ability to continue to use them effectively in human medicine when they are routinely absorbed in low levels through the food chain. Colistin is used very sparingly in humans as it can cause kidney failure; however, when no other antibiotics have been effective, Colistin is an important last resort (AMR Review, 2016). Widespread use of Colistin in animals has led to resistance in animal pathogens which has concerning implications for human health. A recent study in China has shown the discovery of transferable colistin resistance in bacteria in both humans and animals (Yi-Yun Liu et al., 2016).
Benefits of Reducing Unnecessary Use of Antimicrobial Drugs:
- Treatment costs for resistant infections would decrease
- Lower death toll due to AMR
- Fewer resistant infections
- Shorter hospital stays
- More efficient use of healthcare resources
- Continued efficacy of current antimicrobials