Antibiotic resistance in Gramnegative bacteria: The BIG THREE.Ab, Pa, and Kp! 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 Professor, Case Western Reserve University School of Medicine Objectives Overview of the problem of ATB R in Gram negative bacteria A. baumannii, Pseudomonas aeruginosa, and Klebsiella pneumoniae Summarize the rapidly expanding landscape of resistance determinants Use this knowledge to devise effective treatment strategies 1
Part I MDR and PDR Ab The clinical challenge of A. baumannii Multi-Drug Resistant (MDR) A. baumannii are among the most problematic pathogens encountered by clinicians 2
A. baumannii - a prime example of a mismatch between unmet medical need and the current antimicrobial research and development pipeline http://www.idsociety.org Why? Ab facts.. Most common drug resistant pathogen in the US and world 50-70% of Ab clinical isolates are now extensively drug resistant (XDR; i.e. resistant to all antibiotics except colistin or tigecycline), reflecting a >15- fold increase since 2000. Pan drug resistant; XDR strains of Ab increased from <4% in 2000 to >60-80% in 2010 3
Does resistance matter? BSI by XDR Ab cause >50-60% mortality In a recent study 13,796 patients in 1,265 ICUs from 75 countries, Ab was one of only two of 19 microorganisms strongly linked (p<0.01) to increased mortality by multivariate analysis; Odds ratio for death-1.53 Factors? LPS, Fe siderophores, PLD, OMPs, biofilm?? McGowan ICHE 2019, Hoffman et al, ICHE 2010, McGowan AJM 2006 Paterson CID 2006, Perez AAC 2007, Vincent JAMA 2009, Gordon JAC 2009 7 housekeeping genes (total 2,976 nt) in 154 diverse A. baumannii strains A. baumannii is a genetically compact species 4
antimicrobial resistance is a major selective advantage that drives the ongoing rapid clonal expansion of these highly problematic agents of nosocomial Infections. 5
Threat 1. β-lactam mediated resistance In A. baumannii resistance to β-lactams presents one of the most significant challenges β-lactamases Efflux mediated elimination-adeabc Penicillin Binding Proteins (PBPs) Outer Membrane Proteins Alterations-5 Omps; β-lactamase Arsenal All representative classes (A-D) AmpC Cephalosporinase (ADC) background nearly 70 now! Emerging Importance of MβL (IMP, VIM, SIM, and NDM) and OXA-type carbapenemases IS elements with ADCs and OXAs; integrons Class A β-lactamases (ESBLs-PER, TEM); role? 6
AmpC (Acinetobacter Derived Cephalosporinases, 70 + ADCs) Differences in expression? TAZ R bla ADC FEP S IS Aba 1 Insertion sequences 1180 bp insert promoter Increased transcripts by RT PCR or increased protein expression Bou et al., 2000, AAC; Mammeri et al., 2003 AAC; Hujer et al., 2006 AAC; Bou et al., 2007 in resubmission Corvec et al., 2003, JACS; Hertier et al., CMI, 2005; Ruiz et al., FEMS, 2007; Babic et al., ICAAC 2007 OXA β-lactamases Naturally occurring and acquired 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 7
Global spread of OXA carbapenemases in Acinetobacter Outbreaks everywhere OXA-24/40* was also the first carbapenemhydrolyzing oxacillinase reported in Chicago (Quinn Lab-signal of emerging problem in US tertiary care centers). both plasmid and chromosomally located OXA-23,-40 and -58 at WRAMC from 2003 to 2005 (US* also UK* troops); outbreak on the West Coast US?? OXA-143 emerging? Lolans et al, AAC 2006; Hujer et al, AAC 2006; Poirel et al, 2010 bla OXA carbapenemases and IMI R? AdeABC IMI R bla oxa-23/40, others IS Aba 1-3-4 Hertier et al., AAC 2005; Poirel et al., AAC 2006 8
ENTER NDM-1!! Thanks Dr. Perez MβLs of Acinetobacter: IMP (22+) and VIM (24) type are major MβLs Others are also being found (SIM-Seoul imipenemase) Integron borne NDM-1, -2 now in Ab Molecular characterization of bla NDM-1 in an Acinetobacter baumannii strain isolated in Germany in 2007 J. Antimicrob. Chemother. (2011) 66(9): 1998-2001 Pfeifer et al. 9
More than one variant? NDM-1 NDM-2 (29 H to A) NDM-3 NDM-4 (154 M to L) Threat 2. Colistin R Polymyxins (E and B) are cationic polypeptide atbs Colistin SO 4 for PO and Colistimethate Na + (sodium colistin methanesulphonate, colistin sulfomethate sodium) for IV Colistin displaces Ca +2 and Mg +2 from PO4-3 groups of membrane lipids; Insertion of polymyxins disrupts the OM and LPS is released ; anti-endotoxin activity ; rapidly bactericidal??? Urban et al. reported a case of polymyxin B R A. baumannii Falgas, et al, CID 2005; Urban 2001 AAC; Li et al AAC 2006; Li et al Int Journal of Antimicrobial Agents, 2005 10
Colistin R Colistin R due to modifications of LPS; pmr (US) vs. lpxa,-c, and -D (Australian); Parks lab in S. Korea found the same locus Heteroresistance (subpopulations of genetically identical subclones that are more R than the parent ) by Li et al; implications for rx? Moffatt AAC 2010, Li et al AAC 2006 ; Hawley et al AAC 2007, Adams et al AAC 2009 Hawley et al. describe the phenomenon of colistin dependence. 77 yo diabetic male with FI and bacteremia; increasingly luxuriant growth Survey of Resistance genes in A. baumannii bla AMEs QRDR RND Efflux pumps OMPs Tet ADC aacc1 gyra AdeABC HMP-AB teta OXA aacc2 parc AdeM OmpA tetb IMP aacc3 AdeIJK 33-36 kda tetm VIM, GIM SIM, SPM, NDM aaca4 AdeS CraS AdeDE 25/29 kda CarO PER apha1 Res Is?? OprD (43kDA) TEM* apha6 AbaR 1-10 OmpW tetx PBPs SHV aada1 Col R pmrab CTX-M rmt* 44, 47kDa, 22 integrons 11
The Resistance Island 86 Kb, 88 orfs, 82 orfs from another source and 45 resistance genes AbaR1-10! Fournier et al., PLoS Genet. 2006 Jan;2(1):e7. Epub 2006 Jan 13. Part II MDR P. aerugoinosa The resistance challenge of the ages 12
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, Mechanisms of resistance 13
Pa and ATB R ß-lactamases-all classes represented Cephalosporinases, class A ESBLs (PER), OXA ESBLs (OXA-10, -14), Carbapenemases (KPC and GES), MβLs Loss of permeability Quinolones and aminoglycosides Active antimicrobial efflux Alterations in DNA gyrase Aminoglycoside-modifying enzymes 14
Antimicrobial resistance Efflux pumps MFS major facilitator superfamily ABC ATP-binding cassette family RND resistance nodulation division SMR small multidrug resistance MATE multidrug and toxic compound extrusion RND and MFS extrude antibiotics and work by proton motive force; In GNRs, RND works with MFP (periplasmic membrane fusion protein) and OEP (outer membrane efflux protein) to get thru both membranes Antimicrobial resistance MexAB-oprM operon Expressed constitutively in wild-type cells; cipro-r, B-lactam-R, TCN-R, macrolide-r, chloro-r, TMP-SMX-R System is also growth phase regulated, its expression increasing in late log phase Transports homoserine lactones (quorum sensing) mexr upstream controls 15
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The mysteries of the biofilm.. Trends in Microbiology Jan 2001; 9(1): 34-39 Part III MDR K. pneumoniae 17
Why should we be afraid of Klebsiella pneumoniae? KPCs and OXA-48! KPC K. pneumoniae AMIKACIN R AMPICILLIN R CEFAZOLIN R CEFTAZIDIME R CIPROFLOXACIN R TRIMETH/SULFA R MEROPENEM 4 ug/ml (> 64) GENTAMICIN S AMPICILLIN/SUL R CEFOTETAN R CEFEPIME R PIP/TAZO R 18
Status of the KPC global epidemic Two phenotypes; MIC< 8 and MIC> 32 ST258> ST384, ST388 Plasmids from ST258 has been transferred to E. coli in patients. Colistin resistant ST258 Novel testing methods (ChromAgar, Boronates, PCR/ESI-MS, Microarray methods/checkpoints Doi, CID, 2011; KPC attack 19
Worst case scenario!! Clinical issues ATB control?cephalosporin and β- Lactam-β Lactamase Inhibitor restriction policies? special populations? How best to implement IC? Carrot or stick? Detection? ESBL identification? Inoculum effect? Colistin-as empiric Rx??? combined with aminoglycosides (gent); rifampin 20
What is the impact of infections caused by KPC producing bacteria? Is there increased mortality?? The mortality in the IRE group was 33%, compared to 9% among controls. Being an IRE case was significantly associated with increased mortality (P 0.043) 21
Goal: identify risk factors associated with mortality among patients with carbapenemresistant K. pneumoniae infx. Results carbr K. pneumoniae infection was independently associated with recent organ or stem-cell transplantation (P =.008), receipt of mechanical ventilation (P =.04), longer LOS before infection (P =.01), ceph (P=.02) and carba (P <.001) exposure. Is there something different about this population of Kp? 22
Results Case patients were more likely than control patients to die during hospitalization (48% vs 20%; P <.001) die from infection (38% vs 12%; P <.001). Removal of the focus of infx (ie, debridement) was independently associated with patient survival (P=.002). The timely administration of antibiotics with in vitro activity against carbapenem-resistant K. pneumoniae was not associated with patient survival. OXA-48 The blaoxa-48 gene with insertion sequence IS1999 in K. pneumoniae. First described in 2004, Turkey, next Tunisia, France, Senegal, the Netherlands, Morocco, Spain, Ireland, Israel Germany; ST 395, carried the blaoxa-48 gene located onto a 62- kb conjugative plasmid 23
Options for treatment? The basis for a new research agenda in Infectious Diseases What can I use to treat MDR Ab, Pa, and Kp when isolates are resistant to all antibiotics? 24
Therapy for MDR Ab, Pa, Kp Colistin? Tigecycline? Minocycline? Rifampin? Teicoplanin? Vancomycin?? Do we have enough patients studied properly? Animal models may have (significant) limitations? Colistin is King 25
After an exhaustive review of much the available evidence. Perez et al, AAC 2007 Most recent reviews Lung infections Munoz-Price and Weinstein, NEJM 2008 26
Colistin + rif? Colistin + minocycline? Not enough data Antagonistic? Synergy? Sometimes??? Meta-analysis (Falagas IJAA)--no statistical difference in cure rates when colistimethate sodium alone was compared with the combinations with meropenem, piperacillin/tazobactam or ampicillin/ sulbactam J of Infec)on, 2006, 53, 274 Need better controls; at least it doesn t hurt yet can it prevent hetero-resistance?? Nation et al, J of Infection 27
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. binfections Colistin and vanco?? 28
Problems Control group?? retrospective design, Variable dosing and duration Other atbs No monitoring of resistance Nephrotoxicity,? which owing to the retrospective character of the studies cannot be attributed exclusively to colistin. Major concerns real? 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. Tigecycline? Patients % Improvement 25 84 18 50 17 82.4 29 30 75 70 34 68 45 78-90% bacteremic patients treated with tige failed to clear their bacteremia 10-fold more commonly than patients treated with comparator drugs Gordon JAC 2009, Gardiner CID 29
Accumulating enough isolates Higgins, JAC 2010 My recommendations Susceptible strains 1. A/S, 3 q6 2. Imipenem; meropenem is worrisome; dori?? Cephalosporins are tricky. 3. Colistin loading dose 5 mg/kg not to exceed 300 mg then (4.5 mg/kg/day) and split it tid(1.5 mg/kg q8). 4. Colistin and rifampin, tigecycline, or minocycline) 30
If NDM-1 Treatment options Aztreonam +?? BAL30072, meropenem and?? Fosfomycin? Release of NXL104 with ceftazidime KPC Rx 68 blakpc-possessing K. pneumoniae including 23 tigecycline- and/or colistin-nonsusceptible strains. By agar dilution, 93% of the overall KpKPC were susceptible (MIC50/90 of 16/64 g/ml, respectively). Notably, 5 out of 6 extremely drug-resistant (tigecycline and colistin nonsusceptible) KpKPC were susceptible to fosfomycin. Compared to agar dilution, disk diffusion was more accurate than Etest. 31
The end? Very complex challenges ahead The prevailing wisdom is find new targets, but can we improve what we currently have? Consider the importance of genomics in helping us understand the changes we are seeing-not new drugs! Diagnostics-Broad range 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 32
Acknowledgments Drs. Keith Kaye and George Alangaden and the organizers of the conference NIH, VA Merit Review; Cubist Chris Bethel, Steve Marshall, Magda Taracila, Kristine Hujer and Andrea Hujer Drs. Krisz Papp-Wallace, Marisa Winkler, Federico Perez, Curtis Donskey, Dror Marcham 33