The persistent abuse and misuse of antibiotics over past decades and the extraordinary adaptive ability of bacteria have led to the emergence of multidrug-resistant bacterial pathogens, that is, bacteria that can cause infection in humans and are resistant to almost all the antibiotics currently available to treat such infections. At the same time, investment in research and development related to new antimicrobial agents has ceased to be a priority for the pharmaceutical industry because of the low financial return they obtain from these drugs compared to other more profitable products. Owing to this combination of factors, we face a situation in the not too distant future where, due to the lack of effective antibiotics, it will no longer be possible to properly treat bacterial infections that today are of minor significance but may soon become deadly diseases.
Investment in research and development related to new antimicrobial agents has ceased to be a priority for the pharmaceutical industry because of the low financial return they obtain from these drugsIn any conversation about bacterial resistance to antibiotics, we must distinguish between two aspects of the problem. Firstly, the acquisition by bacteria of resistance to antibiotics or, what amounts to the same thing, the emergence of strains of bacteria that are resistant to antibacterial agents. Bacteria become resistant either through mutations in the bacterial genome or through the acquisition of mobile genetic elements carrying antibiotic-resistant genes. In the latter case, resistance develops without the presence of antibacterial agents. Exposure to antibiotics exerts the selective pressure needed to favour the emergence of the resistant strains. Consequently, the driving force behind the growing rates of antibiotic resistance can be found ultimately in the abuse and misuse of antibacterial agents in both humans and animals and the release of antibiotics into the environment.
The second aspect of the problem is the spread of resistant bacteria between different ecosystems. For example:
1. The transfer to humans via the food chain of antibiotic-resistant bacteria selected through the use of antibiotics in animals;
2. The spread of resistant bacteria between the members of a community or family;
3. The spread of resistant bacteria in hospitals from the environment to patients or from one patient to another through contact with health care personnel;
4. The transfer of resistant bacteria from the community to the hospital and vice versa;
5. Resistant bacteria carried by humans or animals that pass into the environment through wastewater systems or manure;
6. The international spread of resistant bacteria through globalised trade and population movements, including tourism and immigration.
Urgent measures are clearly needed in all of these ecosystems to prevent the emergence and spread of multiresistant bacteria. There are many measures that could be adopted, but discussing these individually would require much more space than is available in this article. There are, however, a number of general provisions that should be applied everywhere to prevent the emergence and spread of antibiotic resistance worldwide:
1. The rational use of antibiotics in all settings;
2. The implementation of measures designed to control infection in health care facilities;
3. The development of strategies to reduce the risk of environmental exposure;
4. Investment in the development of rapid diagnostic tests;
5. Promoting research on the prevention and surveillance of antimicrobial resistance;
6. Promoting research and the development of new antimicrobial and non-antimicrobial strategies as well as new antibacterial agents;
7. Improving general awareness about the use of antibiotics and the risks associated with increased resistance.
Preventing antibiotic-resistant bacteria from crossing borders in food or through population movements is an almost impossible task. It is therefore important that every country in the world should cooperate and implement the measures needed to prevent the emergence and national spread of resistant bacteria, thereby also preventing international spread. In short, we need to apply local solutions to a global problem.
[Jordi Vila is head of the Microbiology Department in the Hospital Clínic de Barcelona and director of ISGlobal’s Antibiotic Resistance Initiative ].