- Gene transfer
Bacteria can exchange resistance genes (Figure 2) with bacteria of other species through the movement of plasmids or transposons (Lewis 1995). Drug-resistant tuberculosis arises this way.
Figure 2: Transfer of plasmid between bacteria
- Factors causing antibiotic resistance
Factors causing antibiotic resistance include indiscriminate use of antibiotics, misdiagnosis and spread of counterfeit drugs.
- Indiscriminate use of antibiotics
The primary contributor of antibiotic resistance is the misuse of antibiotics. Although antibiotics only work against bacteria and not viruses, they are still prescribed inappropriately. In US, 50% of 133 million antibiotic prescriptions for patients annually are unsuitable or unnecessary (American Society for Microbiology 2002).
Antibiotics are used extensively in agriculture to promote growth of food animals and crops where 24.6 million pounds of antibiotics are used annually livestock producers in US (Union of Concerned Scientists 2001). About 80% of these antibiotics are excreted, enter ground water and hence, are exposed to bacteria in the environment; causing selective pressure that favors resistant strains (HPA 1999; The Whyfiles 1997).
Figure 3: Antibiotics used in agriculture to promote animal growth
- Misdiagnosis and spread of counterfeit drugs
Underqualified health care workers including doctors and drug dispensers plus terrible diagnostic facilities also contribute towards antibiotic resistance as antibiotics are often prescribed inaccurately (WHO 2000). Alternatively, counterfeit drugs (Figure 3) are consumed where 17% of these drugs contain no active ingredient while 11% contain inadequate active ingredients. In both cases, the medication only wipes out non-resistant organisms and leaves the resistant ones to replicate (WHO 2000).
Figure 3: Samples of counterfeit drugs
- How serious is antibiotic resistance?
Antibiotic resistance is a problem which only brings about negative implications such as extended hospitalisation, lost workdays and sometimes, death. Moreover, it is becoming increasingly severe due to its swift spread, ineffectiveness and lack of alternative antibiotics as well as increasing resistance towards common antibiotics (Appendix A).
- Swift spreading of antibiotic resistance
Through binary fission, bacteria can grow exponentially within a few hours. Once resistance is gained, a population of resistant bacteria will appear swiftly. They then infect humans or animals especially in places like hospitals and old folks’ home where vulnerable people gather (HPA 1999). A study conducted in a Swiss hospital discovered that before 1990, all strains of Escherichia coli are susceptible to fluoroquinolone antibiotics but between 1991 and 1993, 28% of the strains were resistant (The Whyfiles 1997). Infected individuals traveling by planes worsen the situation by transferring the resistant microbes across international borders (HPA 1999).
- Ineffectiveness and lack of alternative antibiotics
Alternative antibiotics for treatment of a certain disease, if available, are generally less effective, cause more side effects, costlier and require larger doses (HPA 1999). For example, the emergence of multi drug-resistant tuberculosis requires the replacement of drugs costing US$ 20 with US$ 2000 ones (WHO 2000). Worse still, no new classes of antibiotics were developed since 1970, thus once-controlled diseases are becoming harder to cure.
Figure 5: The process of new drug development
- Increasing resistance towards widely used antibiotics
The number of bacteria resistant to many different antibiotics has increased, in many cases, tenfold or more (Bren 2002). About 2 million patients in US are infected in the hospital annually whereby approximately 70% of the bacteria causing these infections are resistant towards at least one antibiotic (National Institute of Allergy and Infectious Diseases 2004). Even vancomycin, the world’s most powerful antibiotic, is losing its effectiveness with the emergence of resistant enterococcus and Staphylococcus aureus (Bren 2002; Lewis 1995). If this situation persists, global health might just revert back to the pre-antibiotic era.
- Ways to overcome antibiotic resistance
Although antibiotic resistance cannot be eliminated as it is a natural adaptation process, it can be slowed and contained (Appendix B) through the efforts of the government, medical and veterinary communities, pharmaceuticals, non-profits, physicians and individuals (HPA 1999).
- Government
Governments may curb antibiotic resistance by adopting special national health policies. For instance, the US government set up the Interagency Action Plan to Combat Antimicrobial Resistance in 2001 to address the problem of resistance through surveillance, prevention and control, research and product development (American Society for Microbiology 2002). Governments need to enforce effective guidelines in healthcare institutions and ensure efficacy of antibiotic usage (Bren 2002).
- Medical and veterinary community
Antibiotic resistance be effectively controlled by reducing the amount of antibiotics used in the health industry as well as in agriculture, which currently excessive and unnecessary (HPA 1999). To achieve this, steps such as vaccination, educating and training healthcare workers and implementing guidelines concerning the use of antibiotics can be taken to minimise antibiotic usage (American Society for Microbiology 2002).
- Pharmaceutical companies
As existing antibiotics are losing their effectiveness, pharmaceutical companies need to double their efforts in developing new classes of antibiotics as well as new vaccines to prevent general infections (HPA 1999). This however requires incentives from government bodies in the form of exclusivity rights and accelerated drug approval process (Bren 2002).
- Nonprofit organisations
Nonprofits can also help alleviate the problem of antibiotic resistance. World Health Organisation (Figure 6) has issued a set of recommendations aimed to slow the emergence and reduce the spread of resistant microorganisms globally while Gates Foundation donated US$ 100 million in 1999 for malaria, tuberculosis and HIV research followed many other organisations (American Society for Microbiology 2002).
Figure 6: The role played by World Health Organisation
- Physicians and individuals
Physicians must be responsible when prescribing antibiotics for their patients (Figure 7). Similarly, individuals must also play their part by following their prescription accurately and complete their antibiotic courses to prevent the remaining bacteria from becoming resistant (Bren 2002). They should also be educated about how antibiotics work and how resistance develops, realise the importance of vaccination and practice good hygiene to avoid infections (American Society for Microbiology 2002).
Figure 7: Steps that physicians should take to reduce antibiotic resistance
5.0 Conclusion
To conclude, intensive usage of antibiotics for both medical and economic purposes promoted antibiotic resistance among microbes, to the detriment of human health. All in all, humans must not be too complacent with the advancements of medicine and technology and underestimate the exigency of antibiotic resistance as it has the potential to swell into a global health crisis if no immediate precautions or actions are taken.
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APPENDIX A
APPENDIX B
