why are acinetobacter and pseudomonas so antibiotic resistant?
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Why are Acinetobacter and Pseudomonas so antibiotic resistant?. Robert A. Bonomo, MD Chief, Medical Service Director VISN 10 GRECC Louis Stokes Cleveland VAMC Vice Chairman, Department of Medicine University Hospitals Case Medical Center - PowerPoint PPT PresentationTRANSCRIPT
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Why are Acinetobacter and Pseudomonas so antibiotic
resistant?
Robert A. Bonomo, MDChief, Medical Service
Director VISN 10 GRECCLouis Stokes Cleveland VAMC
Vice Chairman, Department of MedicineUniversity Hospitals Case Medical Center
Professor, Case Western Reserve University School of Medicine
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Appreciation and Disclosures• NIH and VA for supporting • Research grants from Case Western Reserve
University, LSCDVAMC Foundation for Medical Research,
• Pfizer, Steris Corporation, Rib-X, and Check-Points
• Collaborators
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Objectives
• Overview of the problem (and crisis) of ATBR in Gram negative bacteria– MDR A. baumannii and Pseudomonas
aeruginosa, • Summarize the rapidly expanding
landscape of resistance determinants• Use this knowledge to devise effective
treatment strategies
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Part I
MDR and PDR Ab
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Multi-Drug Resistant (MDR) A. baumannii are among the most “problematic
pathogens” encountered by clinicians
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Acinetobacter has evolved many molecular strategies to
escape ALL ANTIBIOTICS that resemble more the
tactics of organized crime than traditional warfare
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The clinical challenge of A. baumannii
• Many hospital acquired infections • Infection control “nightmare” • Relative mortality increased; in many
surveys, seems to be the pathogens associated with increased mortality
• Difficult to treat because of antibiotic resistance ? Convergence of resistance and virulence ?
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Survey of “Resistance genes” in A. baumanniibla AMEs QRDR RND
Efflux pumpsOMPs Tet
ADC aacC1 gyrA AdeABC HMP-AB tetA
OXA aacC2 parC AdeM OmpA tetB
IMP aacC3 AdeIJK 33-36 kDa tetM
VIM, GIMSIM, SPM,
NDM
aacA4 AdeSCraS
AdeDE
25/29 kDa CarO
tetX
PER aphA1 Res Is?? OprD(43kDA)
PBPs
TEM* aphA6 AbaR 1-24 OmpW
SHV aadA1 Col R
pmrAB44, 47kDa, 22 integrons
CTX-M rmt* OMVs
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Fournier et al., PLoS Genet. 2006 Jan;2(1):e7. Epub 2006 Jan 13.
“The Resistance Island”86 Kb, 88 orfs, 82 orfs from another
source and 45 resistance genes
AbaR1-24!
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Major Threat : Carbapenem R• OXAs and MBLs• Naturally occurring and acquired• OXAs- Types and Groups
– Narrow spectrum– Carbapenem hydrolyzing (CHDLs)– ES type
• Carbapenemases (Acinetobacter)– Are not ES; do not have both properties – Imipenem> meropenem
Poirel et al AAC 2010
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Part IIMDR P. aerugoinosa
The resistance challenge of the ages
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Pa facts• Colonization rates by Pa are high in the
hospital (50%); immunity and burn• Seriously ill patients in ICUs. • Aggregate NNISS and EU data
– 20 to 30% of nosocomial pneumonias – 10 to 20% of urinary tract infections
– 3% to 10% of bloodstream infections,
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Mechanisms of resistance in Pa
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Pa and ATBR
• ß-lactamases-all classes represented–Cephalosporinases, –class A ESBLs (PER), –OXA ESBLs (OXA-10, -14), –Carbapenemases (KPC and GES),
MbLs• Loss of permeability (porins and
efflux)
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Back to school: mechanism of action
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Mechanisms of resistance
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Therapy for MDR Ab et al.Colistin?
Tigecycline? Minocycline?
Rifampin?Teicoplanin? Vancomycin?
Do we have enough patients studied properly? Animal
models may have (significant) limitations?
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Colistin is King???
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CID 2010
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The colistin “bottom line” • “Efficacy rate” of 57-76% in IV form;
“microbiological eradication” of 67-90.9%Renal tox 0-37%
• Nebulized colistin (CF studies + others) effective; FDA warning; impact of shift to more resistant strains ; use with IV!!
• 32+ cases “microbiological eradication” in the CNS with ITh/IVe colistin (safe e 1) (2.5 mg/kg, 10-20 mg ITh)
• Colistin was independently associated with higher mortality vs. treatment with sulbactam in patients with A. b infections
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Tigecycline? 1.Rapid resistance can emerge;
2.Cases of breakthrough bacteremia reported;
3. Adequacy of blood levels??
Pachon and Vila Curr Opin Investig Drugs. 2009
Feb;10(2):150-6.
Giamarellou & Poulakou, Drugs. 2009
Michalopoulos A, Falagas ME.Expert Opin Pharmacother.
2010 Apr;11(5):779-88.
Patients % Improvement25 8418 5017 82.429 3075 7034 6845 78-90%
Major concerns…real ?
bacteremic patients treated with tige failed to clear their bacteremia 10-fold more commonly
than patients treated with comparator drugsGordon JAC 2009, Gardiner CID
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Combination therapy for PSDA?
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The worst case scenario?
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Summary• Extraordinary challenge against cunning
pathogens• Basic understanding of molecular biology is
needed (the complexities of resistance genes will only increase)
• Research is needed in therapeutics and infection control
• CALL TO ARMS: Coordinate scientific and clinical trials to answer these important questions