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Antibiotic Resistance why do we care?. Thursday 1/10/2008. Reasons why we might care. If resistant bugs cause higher mortality If resistant bugs cause greater morbidity If resistant bugs are more costly to treat If resistant bugs cause additional disease Resistance ≠ Virulence
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Antibiotic Resistancewhy do we care? Thursday 1/10/2008
Reasons why we might care • If resistant bugs cause higher mortality • If resistant bugs cause greater morbidity • If resistant bugs are more costly to treat • If resistant bugs cause additional disease Resistance ≠ Virulence Do we have evidence for any of these? Is it true for any resistant bug?
How could resistance impact the outcomes? • If resistance is associated with virulence. • Resistance genes alter fitness • Resistant genes may be associated with virulent genes • If there is a delay in administration of appropriate antibiotic Rx. • If treatments of resistant bacteria are more toxic or less efficient (ie vancomycin).
Different perspectives of the impact of resistance • Hospital / third party payer / the patient / society. • Patient vs. Society • Resistance also effects patients who did not have infection from resistant organism: • Broader agents are used for initial empirical Rx. -> • more expensive • more toxic • less effective • have deleterious effects on other commensal bacteria
Comparison of mortality associated with MRSA vs. MSSA / Cosgrove et al. CID 2002
Mortality rates of staphylococcal bacteremia over time / Dancer SJ JAC 2007
Studies reporting impaired outcomes due to VRE Matched cohort study
Studies reporting impaired outcomes due to other resistant pathogens
In the aftermath of early Ab success: • 1960s - US surgeon General William H. Stewart: “(it) is time to close the book on infectious disease and declare the war against pestilence won”. • 2007 - despite Ab • Infectious diseases the 2nd-leading causeof death worldwide • 3rd -leading cause in US. • The reason - global spread of microbial resistance to antimicrobial therapies.
So - we do care, yet… • Do all these studies correctly measure what they aim to? • Do we know this for all bugs? For all antibiotic classes? • What are the correct designs to measure these?