antibiotic overuse – how much does it matter?
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Antibiotic Overuse – how much does it matter?. Thursday 1/17/08 . Spread of resistance. Antibiotic pressure. Human to human transmission. Mechanisms by which Antibiotic use can induce resistance. Lipsitch & Samore EID 2002. - PowerPoint PPT PresentationTRANSCRIPT
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Antibiotic Overuse – how much does it matter?
Thursday 1/17/08
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Spread of resistance
Antibiotic pressure
Human to human transmission
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Mechanisms by which Antibiotic use can induce resistance
Lipsitch & Samore EID 2002
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Antibiotic selection of resistant mutants
Ab treatment => outgrowth of resistant subpopulations or acquire de novo resistance
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Antibiotic pressure => increased load or resistant bacteria
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By eradicating a susceptible strain making the host more susceptible to new acquisition of
strains
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Indirect effect – reduced transmission of susceptible strains to other susceptible hosts
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Antibiotics are drugs with externalities (like pollutants)
• By treating an individual with antibiotics – other individuals in the society are influenced
• Antibiotic treatment – maybe beneficial for an individual but deleterious for society.
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Types of studies that examine the relationship between Ab use and Ab
resistance• Ecological studies
• Individual level studies– Case-control– Quasi-experimental studies– Longitudinal studies
• Mathematical models
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Total Ab use in 26 European countries in 2002/ Goosens et al. Lancet 2005
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Total Ab use in 2004 / Goosens CID 2007
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Correlation between Pen use and PRSP / Goosens et al. Lancet 2005
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Do all antibiotic classes induce resistance similarly? The pneumococcus paradigm / Dagan et
al. PIDJ 2006
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Antibiotic use as a risk factor for MRSA (in ED) / Moran et al. NEJM 2006
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Antibiotic consumption and MRSA, an ecologic study (EID 2004)
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FQ use and FQ-R MRSA and E. coli (community and HA)/ MacDougall et al. CID 2005
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Is there overuse/non-judicious use of antibiotics?
• ~50% of Ab prescriptions are non-judicious
• What is non-judicious use?– Ab for viral infections– Wrong dose– Wrong duration– Wrong Ab class – Broad ab class when narrow is as good
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Why is there non-judicious use?
• Lack of knowledge
• Patient demand
• Uncertainty (of Dx, of risks and benefits)
• Medico-legal issues – fear from lawsuit
• Low awareness to Ab resistance problem
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Effect of antibiotic use in agriculture
• Over 50% of Ab produced in US are used for agricultural purposes
• Use for growth promotion and treatment of food animals
• FQ used to treat chicken:– Identical strains of FQ-R Campylobacter found in
raw chicken as those in humans
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Agriculture use and Ab resistance: Quantifying the effect
• Animal use can be a selective force responsible for the assembly of resistant gene clusters
• Reservoir for resistance-encoding plasmids (or other genetic elements) in animal commensal bacteria
• Bacteria that are shared by food animals and humans (VRE).
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Is it not too late?
• Regulation now may have little or no effect.
• Waiting for conclusive evidence may result in a missed opportunity to prevent damage!