SECTION ONE: The global threat of AMDR
Specific Learning Objective: Understand the global threats of AMDR, including epidemiology and multidrug resistance.
Defining the Problem
Bacteria have evolved diverse protective mechanisms to cope with and survive in the ever-changing environment (Russell 1997). In the course of evolution, bacteria have had ample time to recognize harmful substances, developing and sharing defense mechanisms to ensure their own survival. As a result, antibiotics, naturally produced by bacteria, existed long before humans discovered their properties and used them on an unprecedented scale. Humans coexist with many microorganisms, of which only a small subset presents a threat to health.
The 2008 global antibiotic market was estimated at US $24 billion and is projected to reach US $40.3 billion by 2015 (PRWeb 2011). Antibiotic drugs, including antivirals, antihelminthes, and antifungal preparations, are sold for both therapeutic and industrial (agricultural) uses. The rate of antibiotic prescriptions is on the rise in Greece, Croatia, Denmark, and Ireland for both outpatient and inpatient services. A modest downward trend (1998-2005) was reported for Belgium, the Czech Republic, France, Slovakia, Slovenia, Sweden, and the United Kingdom (Monnet and Kristinsson 2008; Meropol et al. 2009), whereas in the United States and Japan, the overall rate for antibiotic use remains high (Higashi and Furuhara 2009). Some experts are concerned that we are entering a critical “postantibiotic era” with a decreasing pipeline of new and effective antibiotics and rising trends in mortality from AMDR (Alanis 2005).
The importance of the AMDR threat has been recently highlighted by the WHO (World Health Organization “Combat antibiotic resistance” 2011) as follows.
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Infections caused by resistant microorganisms often fail to respond to conventional treatment, often leading to prolonged illness and greater mortality risk
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About 440,000 new cases of multidrug-resistant tuberculosis (MDR-TB) emerge annually, causing at least 150,000 deaths
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Resistance to earlier generations of antimalarial preparations such as chloroquine and sulfadoxine-pyrimethamine is widespread in most malaria-endemic countries
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Inappropriate and irrational use of antimicrobial drugs does provide a fertile environment for resistant microorganisms to emerge, spread, and persist
The economic burden of AMDR is estimated to exceed US $38 billion (Tucker 2010). Nearly 7 out of every 1000 hospitalized patients (in economically developing countries) are either infected with or carriers of microorganisms resistant to common antibiotic drugs. In US hospitals, 96,000 patients contract nosocomial infection(s) annually, making such infections one of the 10 leading causes of death, claiming between 16,000 and 19,000 lives each year. The 2000 EU hospital estimates (Kaier et al. 2008) of AMDR infection incidence found that:
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Thirty percent to 40% of cases are linked to cross-infection by the hands of healthcare workers (HCW)
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Twenty percent to 25% of cases are due to selective antimicrobial pressure
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Twenty percent to 25% of patients suffer from new pathogen introduction
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