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  1. Dr.T.V.Rao MD CARBAPENAMS Uses and Reistance Dr.T.V.Rao MD

  2. Penicillins Cephalosporins Carbapenems Quinolones Amino glycosides Macrolides Tetracyclines Nitrofurantoin, metronidazole, clindamycin, vancomycin, teicoplanin, cotrimoxazole, fusidic acid, etc Isoniazid, pyrazinamide, ethambutol, rifampin, cycloserine, etc Dr.T.V.Rao MD Conventional antibiotics

  3. Dr.T.V.Rao MD Carbapenems xpenicillins • The carbapenems are structurally very similar to the penicillins, but the sulphur atom in position 1 of the structure has been replaced with a carbon atom, and hence the name of the group, the carbapenem

  4. 50 penicillins 71 Cephalosporins 12 Tetracyclines 8 amino glycosides 1 monobactam >3 carbapenems 9 macrolides 2 streptogramins 3 dihydrofolate reductase inhibitors 1 oxazolidinone 5.5 quinolones Dr.T.V.Rao MD Antibiotic formulation continue to growCONTINUE TO CONFUSE

  5. A Changing Landscape forNumbers of Approved Antibacterial AgentsWe have more resistant Microbes 18 16 14 12 10 Number of agents approved 8 6 4 0 2 0 Dr.T.V.Rao MD Resistance 1983-87 1988-92 1993-97 1998-02 2003-05 2008 Bars represent number of new antimicrobial agents approved by the FDA during the period listed. Infectious Diseases Society of America. Bad Bugs, No Drugs. July 2004; Spellberg B et al. Clin Infect Dis. 2004;38:1279-1286; New antimicrobial agents. Antimicrob Agents Chemother. 2006;50:1912

  6. Carbapenems are a class of beta-lactam antibiotics with a broad spectrum of antibacterial activity. They have a structure that renders them highly resistant to beta-lactamases. Carbapenem antibiotics were originally developed from thienamycin, a naturally-derived product of Streptomycescattleya. Dr.T.V.Rao MD What are carbapenems

  7. Dr.T.V.Rao MD Carbapenems common uses • Imipenem • Broad spectrum, covers Gram-positive, Gram-negative (including ESBL-producing strains), Pseudomonas and anaerobes • Meropenem • Less seizure-inducing potential, can be used to treat CNS infections • Ertapenem • Lacks activity vs. Acinetobacter and Pseudomonas • Has limited activity against penicillin-resistant pneumococci

  8. Dr.T.V.Rao MD How are Carbapenems Used? Uses by Clinical Syndrome • Bacterial meningitis • Hospital-associated sinusitis • Sepsis of unknown origin • Hospital-associated pneumonia Use by Clinical Isolate • Acinetobacter spp. • Pseudomonas aeruginosa • Alcaligenesspp. • Enterobacteriaceae • Mogenella spp. • Serratia spp. • Enterobacter spp. • Citrobacter spp. • ESBL or AmpC + E. coli and Klebsiellaspp. Reference: Sanford Guide

  9. Dr.T.V.Rao MD Enterobacteriaceae are real problamatic microbes • The rapid and disturbing spread of: • extended-spectrum ß-lactamases • AmpC enzymes • carbapenem resistance • metallo-β-lactamases • KPC and OXA-48 β-lactamases • Quinolones resistance

  10. Dr.T.V.Rao MD Carbapenems effective on several common isolates • Staph (not MRSA), Strep (highly resistant), Neisseria, Haemophilus, Proteus, Pseudomonas, Klebseilla, Bacteroides, anaerobes (excluding C. dif) • .

  11. These agents have the broadest antibacterial spectrum compared to other beta-lactam classes such as penicillins and cephalosporins. Additionally they are generally resistant to the typical bacterial beta-lactamase enzymes which are one of the principal resistance mechanisms of bacteria. They are active against both Gram positive and gram negative bacteria, with the exception of intracellular bacteria, such as the Chlamydia Dr.T.V.Rao MD Carbapenems are broad spectrum antibiotic

  12. Dr.T.V.Rao MD Drugs belong to the carbapenem class: • Imipenem • Meropenem Ertapenem Doripenem Panipenem/ betamipron Biapenem

  13. These agents have the broadest antibacterial spectrum compared to other beta-lactam classes such as penicillins and cephalosporins. Additionally they are generally resistant to the typical bacterial beta-lactamase enzymes which are one of the principal resistance mechanisms of bacteria. They are active against both Gram positive and gram negative bacteria, with the exception of intracellular bacteria, such as the Chlamydia. Dr.T.V.Rao MD broadest antibacterial spectrum

  14. Carbapenems Dr.T.V.Rao MD

  15. Spectrum of Activity Dr.T.V.Rao MD

  16. The most versatile family of -lactamases • Two major groups based on the hydrolytic mechanism at the active site • Serine at the active site: class A and D • Zinc at the active site: class B • All carbapenemases hydrolyze penicillins, extended spectrum cephalosporins, and carbapenems Dr.T.V.Rao MD Carbapenemases

  17. Carbapenemase hydrolyzing enzymes • Porin loss “OprD” • ESBL or AmpC + porin loss Dr.T.V.Rao MD Mechanisms of Carbapenem Resistance

  18. Carbapenamases Dr.T.V.Rao MD

  19. Carbapenamases constitute the most versatile family of β-lactamases belonging to molecular classes A, B and D and are capable of hydrolyzing almost all β-lactams. Given their zinc dependent hydrolytic activity, Carbapenamases of class B is designated as metallo-ß-lactamases (MBL) that include, for example, IMP, GIM, SIM, SPM, and VIM carbapenemases, and these MBL enzymes have been reported in P.aeruginosa and other multidrug resistant pathogens Dr.T.V.Rao MD Carbapenamases are complex in Mechanisims

  20. Dr.T.V.Rao MD Carbapenemases • Ability to hydrolyze penicillins,cephalosporins, monobactams, and carbapenems • Resilient against inhibition by all commercially viableß-lactamase inhibitors • Subgroup 2df: OXA (23 and 48) carbapenemases • Subgroup 2f : serine carbapenemases from molecular class A: GES and KPC • Subgroup 3b contains a smaller group of MBLs that preferentially hydrolyze carbapenems • IMP and VIM enzymes that have appeared globally, most frequently in non-fermentative bacteria but also in Enterobacteriaceae

  21. A new class of bacterial enzymes capable of inactivating Carbapenems, known as Klebsiella pneumoniae Carbapenamases (KPCs), has rapidly spread in the United States and continues to be extensively reported elsewhere in the world. KPCs are class A Carbapenamases that reside on transferable plasmids and can hydrolyze all pencillins, cephalosporins, and Carbapenems. Dr.T.V.Rao MD Carbapenamases are spreading faster

  22. KPC carbapenemase Difficult to detect using current MIC breakpoints. Isolates that have an MIC of 2 mg/ml to ertapenem or an MIC of 2-4 mg/ml tomeropenem or Imipenem. Modified Hodge test is confirmatory. Discussed in manual. PCR is gold standard. Dr.T.V.Rao MD Carbapenemases within the Enterobacteriaceae

  23. Dr.T.V.Rao MD KPC (K. pneumoniae carbapenemase) • KPCs are the most prevalent of this group of enzymes, found mostly on transferable plasmids in K.pneumoniae • Substrate hydrolysis spectrum includescephalosporins and carbapenems

  24. KPC’s in Enterobacteriaceae Pseudomonas aeruginosa – Columbia & Puerto Rico Dr.T.V.Rao MD

  25. Dr.T.V.Rao MD Pseudomonas aeruginosaCarbapenamases • KPC resistance has been reported in inherently resistant organisms such as Pseudomonasfrom Trinidad, an isolate of multidrug-resistant Pseudomonas aeruginosa that harboured a novel KPC-6 gene was detected.

  26. Dr.T.V.Rao MD Emerging Carbapenem Resistance in Gram-Negative Bacilli • Significantly limits treatment options for life-threatening infections • No new drugs for gram-negative bacilli • Emerging resistance mechanisms, carbapenemases are mobile, • Detection of carbapenemases and implementation of infection control practices are necessary to limit spread

  27. Enterobacteriaceae: Breakpoints revised so need for other newer drugs, may be carbapenms? Dr.T.V.Rao MD

  28. Dr.T.V.Rao MD Resistance to Carbapenems • Carbapenems = ertapenem, imipenem, meropenem • Intrinsically less susceptibleorganisms – Acinetobacter, P. aeruginosa • Other organisms may acquire resistance – K. pneumoniae, other Enterobacteriaceae • Know mechanisms of carbapenem resistance: • Class A carbapenemases (KPC, SME,…) • Class B metallo-β-lactamases (IMP, VIM, SPM…) • Class D oxa 23, -40, -51, -58 • Organisms that acquire these resistance mechanisms will be resistant to all carbapenems but may test susceptible to imipenem

  29. Carbapenemase Classification Dr.T.V.Rao MD

  30. Emerging Metallo-β-Lactamaseswith Mobile Genetics(SENTRY Program 2001-2005) Dr.T.V.Rao MD

  31. Dr.T.V.Rao MD Resistance to Carbapenems • Can also have carbapenem resistance due to • Class A ESBL’s (CTX-M) + reduced permeability • Class C High AmpC + reduced permeability • These hydrolyze ertapenem more than meropenem or imipenem

  32. First identified 1982 in UK • Four major families • Chromosomally encoded • Serratia marcescens enzyme (SME) • Not metalloenzyme carbapenemases (NMC) • Imipenem-hydrolyzing -lactamases (IMI) • Plasmid encoded • Klebsiella pneumoniae carabapenemases (KPC) • Guiana Extended-Spectrum (GES) Dr.T.V.Rao MD Carbapenemase Class A

  33. Dr.T.V.Rao MD Class A Carbapenemases • K. pneumoniae carbapenemase (KPC-type) possess carbapenem-hydrolyzing enzymes most common on East Coast of U.S. • Enzymes are capable of efficiently hydrolyzing penicillins, Cephalosporins, aztreonam, and carbapenems and are inhibited by clavulanic acid and tazobactam • To date 4 KPC enzymes have been identified: KPC-1, KPC-2, KPC-3, KPC-4 – E. coli, K. pneumoniae, K. oxytoca, E. cloacae

  34. Dr.T.V.Rao MD Carbapenemase-Producing Klebseilla pneumonia (KPC) • KPC-3 is the most recently reported enzyme in that group • KPC-3 is closely related to its predecessors, differing by only 1 amino acid from KPC-2 and by 2 amino acids from KPC-1 • It has been recovered from isolates of K. pneumoniae, E. coli, and E. cloacae

  35. Carbapenem Resistance: Mechanisms Dr.T.V.Rao MD

  36. Carbapenemases Dr.T.V.Rao MD

  37. Dr.T.V.Rao MD KlebsiellaPneumoniae and Carbapenemase • KPC is a class A b-lactamase • Confers resistance to all b-lactams including extended-spectrum cephalosporins and carbapenems • Occurs in Enterobacteriaceae • Most commonly in Klebsiella pneumoniae • Also reported in: K. oxytoca, Citrobacterfreundii, Enterobacter spp., Escherichia coli, Salmonella spp., Serratia spp., • Also reported in Pseudomonas aeruginosa (Columbia)

  38. Dr.T.V.Rao MD KPC Enzymes • Located on plasmids; conjugative and nonconjugative • blaKPC is usually flanked by transposon sequences • blaKPC reported on plasmids with: • Normal spectrum b-lactamases • Extended spectrum b-lactamases • Aminoglycoside resistance

  39. Molecular class A and functional group 2f • Inhibited by clavulanic acid but not by EDTA • Confers resistance to ALL -LACTAM antibiotics • Plasmid-encoded • Associated with other resistant genes (aminoglycosides, fluoroquinolones) • Transferable Dr.T.V.Rao MD KPC Enzymes

  40. Predominantly in K. pneumoniae (KP) Reported in Enterobacter spp., Salmonella spp., E. coli, P. aeruginosa, and Citrobacter spp. First identified in KP clinical isolate from North Carolina in 1996 (KPC-1) KPC-2, -3, and -4 have been reported. Mostly identified on the East cost Dr.T.V.Rao MD KPC Epidemiology

  41. KPC producers have been identified outside USA • France • Brazil • Columbia • China • Not detected at the University of Nebraska Medical Center • 45 ESBL-like isolates collected-6 had elevated carbapenem MICs-none contained KPC Dr.T.V.Rao MD KPC Epidemiology

  42. K. Pneumoniae with carbapenemase-producing clones Dr.T.V.Rao MD Norman P et al. LID 2009

  43. KPC carbapenemase Difficult to detect using current MIC breakpoints. Isolates that have an MIC of 2 mg/ml to ertapenem or an MIC of 2-4 mg/ml tomeropenem or Imipenem. Modified Hodge test is confirmatory. Discussed in manual. PCR is gold standard. Dr.T.V.Rao MD Carbapenemases within the Enterobacteriaceae

  44. Major families of β-lactamases of clinical importance Dr.T.V.Rao MD Bush K and Jacboy G AAC 2010

  45. Dr.T.V.Rao MD When to Suspect a KPC-Producer • Enterobacteriaceae – especially Klebsiella pneumoniae that are resistant to extended-spectrum cephalosporins: • MIC range for 151 KPC-producing isolates • Ceftazidime 32 to >64 mg/ml • Ceftriaxone ≥ 64 mg/ml • Cefotaxime ≥ 64 mg/ml • Variable susceptibility to cefoxitin and cefepime

  46. Newer Carbapenemases • As of June 2010, there were three reported cases of Enterobacteriaceae isolates bearing this newly described resistance mechanism in the US, the CDC stated that "All three U.S. isolates were from patients who received recent medical care in India."

  47. The isolate, Klebseilla pneumoniae 05-506, was shown to possess a metallo-beta-lactamase (MBL) but was negative for previously known MBL genes. Gene libraries and amplification of class 1 integrons revealed three resistance-conferring regions; the first contained bla(CMY-4) flanked by ISEcP1 and blc. The second region of 4.8 kb contained a complex class 1 integron with the gene cassettes arr-2, a new erythromycin esterase gene; ereC; aadA1; and cmlA7 CDC reports the new genetic mechanisms

  48. An intact ISCR1 element was shown to be downstream from the qac/sul genes. The third region consisted of a new MBL gene, designated bla(NDM-1), flanked on one side by K. pneumoniae DNA and a truncated IS26 element on its other side. The last two regions lie adjacent to one another, and all three regions are found on a 180-kb region that is easily transferable to recipient strains and that confers resistance to all antibiotics except fluoroquinolones and colistin. NDM-1 shares very little identity with other MBLs, with the most similar MBLs being VIM-1/VIM-2, with which it has only 32.4% identity. Genetic origin of the NDM-1

  49. NDM-1 also has an additional insert between positions 162 and 166 not present in other MBLs. NDM-1 has a molecular mass of 28 kDa, is monomeric, and can hydrolyze all beta-lactams except aztreonam. Compared to VIM-2, NDM-1 displays tighter binding to most Cephalosporins. Molecular configuration of NDM-1