1. 2 Extended-Spectrum-β Lactamase (ESBLs) Extended-Spectrum-β Lactamase (ESBLs) 3

Click here to load reader

  • date post

    12-Jan-2016
  • Category

    Documents

  • view

    220
  • download

    2

Embed Size (px)

Transcript of 1. 2 Extended-Spectrum-β Lactamase (ESBLs) Extended-Spectrum-β Lactamase (ESBLs) 3

  • Extended-Spectrum- Lactamase(ESBLs)

    *

  • HistoryPul Ehrlis 1910 Salvarsan Gerhard Domagk 1935 Sulfanilamid Alexander Fleming 1929 Penicillin Ernest Chain and Howard Florey 1941 the drug was tested

  • Classes of antibacterial agentsBasis of the mechanism of action: 1-Inhibitors of cell wall synthesis 2-Inhibitors of cytoplasmic membrane function 3-Inhibitors of protein synthesis 4-Inhibitors of nucleic acid synthesis 5-antimetabolites

  • Inhibitors of cell wall synthesis1-Beta- lactams Penicillins,Cephalosporins,Carbapenems, Monobactams 2-Glycopeptides: Vancomycin,teicoplani (active only against G-P)

  • b-Lactams: Classification (1)PenicillinsNarrow-spectrum penicillinsBroad-spectrum penicillins-lactamase inhibitor combinationsOxacillin derivativesCephalosporins (ATC/WHO 2005 classification)1st generation: Gram-positive cocci (GPCs), some Gram-negative bacilli (GNBs)2nd generation: some GNBs, anaerobes3rd generation: many GNBs, GPCs 4th generation: many GNBs resistant to 3rd generation, GPCs

  • b-Lactams: Classification (2)CarbapenemsImipenem, meropenem, ertapenemMonobactamsAztreonam

  • The -lactam family of antibioticsCeftriaxone 3rdTicarcillinCeftazidime 3rdMezlocillinCefotaxime 3rdCarbenicillinErtapenemCefmetazoleCefuroxime 2ndAmpicillinMeropenemCefotetanCefamandole 2ndMethicillinAztreonamImipenemCefoxitinCephalothin 1stBenzyl-penicillinMonobactamsCarbapenemsCephamycinsCephalosporinsPenicillinsCefepime 4th

  • DefinitionsNarrow-spectrum -lactam agentsActive against G- or G+ bacteria only; e.g., penicillin Broad-spectrum -lactam agentsActive against G- and G+ bacteria; e.g., ampicillin, 1st generation cephalosporins

    *

  • Definitions (cont)Extended-spectrum -lactam agentsEnhanced activity against G- and some G+ bacteria; e.g., 3rd and 4th generation cephalosporins, carboxy- and ureidopenicillinsExtended-spectrum -lactamases (ESBLs)Enzymes produced by GNR that destroy certain extended-spectrum -lactam agents, including 3rd generation cephalosporins

    *

  • Mechanism of actionBinding to penicillin Binding Protein(P B P) this protein are carboxypeptidase ,aminopeptidase and transpeptidase enzymes Inhibition of one or more of this enzymes accumulation of precursor cell wall unit cell's autolytic system to be activated and results finally cell lyses

  • Resistance to b-Lactams

  • Resistance1-Alteration in target site 2-Production of beta- lactamases Genes encoding are found on the chromosome (generally G-N) and on the plasmid (generally G-P )

  • Beta-lactamase inhibitorsResemble -lactam antibiotic structureBind to -lactamase and protect the antibiotic from destructionMost successful when they bind the -lactamase irreversiblyThree important in medicineClavulanic acidSulbactamTazobactam

  • -lactamase inhibitorsClavulonic acid: derived from Streptomyces clavuligerusLittle antibiotic effect in itselfGiven in combination with a -lactam AbFunction: by binding the -lactamase enzyme more efficiently than the actual -lactamThus protect the -lactam Ab from hydrolysisNot efficient against cephalosporinases

  • Plasmid-mediated TEM and SHV -lactamasesAmpicillin1965TEM-1E.coliS.paratyphi1970sTEM-1Reported in 28 Gm(-) sp1983ESBL in Europe1988ESBL in USA2000> 130 ESBLsWorldwideExtended-spectrumCephalosporins1963Evolution of -Lactamases*

  • History of GNR resistance1928Fleming1941Penicillin use1940 Penicillinase detected in E. coli1959 -lactamase resistant penicillins: Methicillin1960sBroad spectrum/ extended spectrum penicillins1964Cefalotin use1965 Broad spectrum lactamases (TEM-1 in E. coli)1983 Extended spectrum -lactamases1985Carbapenem (Imipenem)Early 1980s3rd generation ceph.CarbapenemasesTEM-1 widespread2005 TigecyclineESBL outbreaks in France1976 lactamases inhibitors

  • Ambler Classification of -LactamasesActive siteNucleotide sequenceFour evolutionarily distinct molecular classesACDSerine-enzymesBZinc-enzymes-lactamases

  • Modified BushJacobyMedeiros Classification of bLactamases

    Functional Substrate profile

    Group

    Molecular Class

    Inhibitor

    Example

    1

    Cephalosporinase

    C

    Oxa

    AmpC, MIR-1

    2a

    Penicillinase

    A

    Clav.

    S.aureus

    2b

    Broad spectrum

    A

    Clav.

    TEM-1/2, SHV-1

    2be

    Extended spectrum

    A

    Clav.

    TEM 3-29, TEM46-104 SHV2-28, CTX-M types

    2br

    Inhibition resistant

    A

    -

    TEM 30-41 (IRT1-12)

    2c

    Carbenicillinase

    A

    Clav.

    PSE-1

    2d

    Oxacillinase

    D

    (Clav.)

    OXA-1 (OXA-2 &-10 derived ESBL)

    2e

    Cephalosporinase

    A

    Clav.

    FPM-1 P. vulgaris, CepA B. fragilis.

    2f

    Carbapenemase

    A

    Clav.

    IMI-1, NmcA, Sme 1-3

    3

    Metallo-enzyme

    B

    -

    S.maltophilia

    4

    Penicillinase

    -

    -

    B.cepacia

  • Extended-Spectrum -Lactamases (ESBL)Confers resistance to penicillins and 1st, 2nd and 3rd generation cephalosporins Inhibited by -Lactamase inhibitorsMost common CTX-M, TEM and SHV>300 have been identifiedPlasmid-mediated, highly mobileOften associated with resistance genes to aminoglycoside, TMP/SMX and tetracycline Associated with fluoroquinolone resistance phenotype

  • Types of ESBLsTEMSHVCTX-MOXA

  • Evolution of TEM EnzymesMIC (mg/mL) ceftazidime102162TEM-1 0.25

    glutaminearginine

    TEM-122.0glutamineserine

    TEM-26128lysineserine

  • Enzyme Ceftaz Amino Acid Position MIC104164240TEM-1 0.12GluArgGluTEM-10 > 256GluSerLysTEM-12 16GluSerGluTEM-26 256LysSerGlufrom: Jacoby, IDCNA 11:875, 1997Molecular Basis of ESBLs

  • Other ESBLsCTX-M preferentially hydrolyze cefotaxime. - found in strains of Salmonella enterrica- E.coli and other species of Enterobacteriaceae OXA

    Mainly in P.aeroginosa

    6

  • Other ESBls (cont,n)PER-1 :Discovered in P.aeruginosa (turkey)PER-2 In south AmericaVEB-1 E.coli (Vietnam)CME-1 Chrysobacterium meningosepticum( Thailand)TLA-1 E.coli ( Mexico )Patrica A Cli Microbiol Rev 14; 2001

  • ESBls are clinically importantThey destroy cephalosporinsDelayed recognition and inappropriate treatment of sever infection ESBls mediated resistance is not always obvious to all cephalosporinsMany ESBL produce multi-resistant to non- -lactam antibiotics such as quinolons .aminoglycosides and trimethoprime 13

  • Why is important to do special tests and follow complex reporting rules for ESBLs?In vitro tests may be misleading (e.g., may see S in vitro but drug may not work!)Many types of ESBLs with varying susceptibility profiles (TEM 130; SHV 50; CTX-M 30)Treatment failures (esp. bacteremia) when patient treated with 3rd generation cephalosporinsESBL-producing isolates can cause nosocomial outbreaks

    *

  • Which microorganisms are ESBls positiveK.pneumoniae and K.oxytocaE.coliEnterobacter sppSalmonella sppMorganell morganii,Proteus mirabilisSerratia marcescensPseudomonas aeruginosa

    16

  • ESBL TestingOrganisms E. coli, Klebsiella spp., Proteus mirabilis Screen test: Decreased susceptibility to extended-spectrum -lactamsPhenotypic confirmatory test: -lactam activity restored by -lactamase inhibitor (i.e. clavulanic acid)*

  • ESBL Screening Test Disk zone (mm) MIC (g/ml) *Cefpodoxime 17 >4***Ceftazidime 22 >1*Cefotaxime 27 >1 Ceftriaxone 25 >1 Aztreonam 27 >1* only these drugs appropriate for P. mirabilis**>1 g/ml for P. mirabilis

  • ESBL Phenotypic Confirmatory TestTest:cefotaximecefotaxime/clavulanic acidceftazidimeceftazidime/clavulanic acid Results:clavulanic acid restores activity of cefotaxime or ceftazidime or bothQC E. coli ATCC 25922; K. pneumoniae ATCC 700603

  • CLSI Confirmatory Test Klebsiella, E. coli, P. mirabilis

    MIC Testcefotaxime and ceftazidime +/- 4 g/ml clavulanate:> 3 doubling dilution decrease with either drug

    Disk Testcefotaxime and ceftazidime +/- 10 g clavulanate> 5 mm zone increase

    e.g.ceftazidime 8 g/mlceftazidime + clavulanate 1 g/ml

  • ESBL Confirmatory TestPositive for ESBLCeftaz/CACefotax/CACeftazCefotax*

  • ESBL Confirmatory Test Negative for ESBL

    Ceftaz/CACefotax/CACeftazCefotax*

  • E-test for detection of ESBLs

    AB Biodisk (Solna,Sweden) has introduced a two sided ESBL E-test strip that contain either a combination of ceftazidime and ceftazidime/clavulani acid or cefotaxime and cefotaxime /clavulanic acid

  • E-test for detection ESBlsBoth strips have a decreasing gradient of ceftazidime or cefotaxime alone on one end and a decreasing gradient of ceftazidime or cefotaxime plus a fixed gradient of clavu