Cephalosporin resistance in E.coli
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Cephalosporin resistance in E.coli



Cephalosporin resistance in E.coli

Cephalosporin resistance in E.coli



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Cephalosporin resistance in E.coli Cephalosporin resistance in E.coli Presentation Transcript

  • Cephalosporin Resistant Escherichia coli Dr.T.V.Rao MD Dr.T.V.Rao MD 1
  • Beta-lactam antibioticsPenicillins Ampicillin Amoxicillin PiperacillinCephalosporins (generations) 1st gen: cephalothin 2nd gen (Cephamycins): cefoxitin, cefotetan 3rd gen: ceftazidime, cefotaxime, ceftriaxone 4th gen: cefepime Dr.T.V.Rao MD 2
  • Definition of beta lactamases Beta lactamases are enzymes produced by some gram- positive and gram-negative bacteria that hydrolyze beta lactam antibiotics Dr.T.V.Rao MD 3
  • The β-lactam family of antibiotics PenicillinsCephalosporins Cephamycins Carbapenems Monobactams Benzyl- penicillin Cephalothin 1st Cefoxitin Imipenem Aztreonam Cefamandole Methicillin Cefotetan 2nd Ampicillin Cefuroxime 2nd Cefmetazole Ertapenem Carbenicillin Cefotaxime 3rd Mezlocillin Ceftazidime 3rd Ticarcillin Ceftriaxone 3rd Cefepime 4th Meropenem Dr.T.V.Rao MD 5
  • Other Beta-lactam antibioticsMonobactam: aztreonamCarbapenems: Imipenem Meropenem ErtapenemInhibitors Sulbactam (ampicillin/sulbactam: Unasyn) Tazobactam (piperacillin/tazobactam: Zosyn) Clavulanate (amoxicillin/clavulanate: Augmentin) Dr.T.V.Rao MD 6
  • What are 3 rd Generation CephalosporinsThird-generation cephalosporins arebroad-spectrum drugs with highintrinsic activity against gram-negativespecies. The rising resistance to thesedrugs is worrisome because it couldbe a proxy for the emergence andspread of Enterobacteriaceae strainsproducing extended-spectrum β-lactamase Dr.T.V.Rao MD 7
  • -Lactamase Activity H H -lactam S R-CONH C C CH3 C N CH3 O COOHEnzyme-Ser-OH Dr.T.V.Rao MD 8
  • -Lactamase Activity H H S R-CONH C C CH3 O C N CH3 O H COOH HOH Ser Enzyme Dr.T.V.Rao MD 9
  • L  L L       L     L L    L  -lactamase L  production L Dr.T.V.Rao MD  10
  • MODE OF ACTION OF BETA LACTAMS IN GRAM NEGATIVESSUSCEPTIBLE RESISTANT-Lactam Antibiotic Diffusion through  Porin Blocks EntryOuter Membrane  Efflux Pump Diffusion through  Beta-Lactamase Peptidoglycan Hydolyzes Beta-Lactam Penicillin Binding Proteins  Changes in PBP results in  Failure to Bind to -Lactam Cell Death Dr.T.V.Rao MD 11
  • Some beta-lactamases only inactivate a small number of antibiotics e.g. penicillinOthers have extended spectrum to all the penicillins and cephalosporins e.g. cefuroxime, ceftriaxone (ESBLs)In addition may also carry resistance to other antibiotics e.g. ciprofloxacin. Dr.T.V.Rao MD 12
  • What it means as ESBLsExtended-spectrum beta-lactamases (ESBLs) are mutant enzymes with a broader range of activity than their parent moleculesThey: Hydrolyze 3rd and 4th gen cephalosporins and aztreonam Do not affect Cephamycins (2nd gen ceph) or Carbapenems Remain susceptible to beta-lactamase inhibitors Dr.T.V.Rao MD 13
  • Classical ESBLsPrimarily found in E. coli and Klebsiella spp.Differ from their parent TEM or SHV enzymes by only 1-4 amino acids>100 TEM- or SHV-derived beta-lactamases have been described – most are ESBLs Dr.T.V.Rao MD 14
  • Non-classical ESBLsMany described, but less common than classical ESBLs CTX-M Found in multiple genera of Enterobacteriaceae Preferentially hydrolyze cefotaxime U.S., Europe, South America, Japan, Canada OXA Mainly in P. aeruginosa Primarily hydrolyze ceftazidime France, Turkey Dr.T.V.Rao MD 15
  • ESBLs Extended-spectrum β-lactamases>180 enzymes described (119 TEM, 45 SHV)All mutations of older TEM and SHV plasmid-mediated β - lactamases TEM-3, TEM-4, etc. SHV-2, SHV-3, etc. CTX-M-1,2, etc. and Toho-type OXA-type PER-1 and 2Resistance conferred to extended-spectrum penicillins, 3rd and 4th generation cephalosporins and aztreonam (not imipenem or cephamycins) www.lahey.org/studies/webt.htm Dr.T.V.Rao MD 16
  • Extended-Spectrum β- Lactamasesβ-lactamases capable of conferring bacterial resistance to the penicillins first-, second-, and third-generation cephalosporins aztreonam (but not the Cephamycins or Carbapenems)These enzymes are derived from group 2b β- lactamases (TEM-1, TEM-2, and SHV-1) differ from their progenitors by as few as one AA Dr.T.V.Rao MD 17
  • Plasmid-Mediated AmpCsB-lactamases derived fromchromosomally encoded clavulanate-resistant AmpC cephalosporinases ofCitrobacter, Enterobacter &Morganella spp.Genes are typically encoded on largeplasmids and carry additionalresistance genes Dr.T.V.Rao MD 18
  • Some premises• Growing resistance to 3-gen cephalosporins• Mostly ESBLs in E. coli & Klebsiella; AmpC in Enterobacter, Citrobacter, Serratia… but not always• Identification of mechanism aids – Epidemiological investigation / control – Treatment choice – Recognition of the exceptional e.g. MBLs Dr.T.V.Rao MD 19
  • Resistance in E.coli a global concern IN 2009, E coli resistancelevels to third-generationcephalosporins in theUnited States comparedfavourably with those ofthe rest of the developedworld with rates aboutequal to those inScandinavian countries(Iceland, Estonia,Norway), and a lowerreported resistance thanthe Netherland Dr.T.V.Rao MD 20
  • ESBLs characterization TEM ESBLs- More than 30 described- TEM-6, TEM-10, TEM-12, and TEM-26 SHV ESBLs- More than 10 CTX-M ESBLs AmpCDerived from chromosomal AmpC genes of gram-negative organisms, such as Citrobacter freundii,Enterobacter cloacae, and Aeromonas spp. Dr.T.V.Rao MD 21
  • Detecting ESBL producers steps:• Screen for resistance with an indicator cephalosporin• Do confirmatory test on those found resistant Dr.T.V.Rao MD 22
  • Choice of indicator cephalosporin Sensitivity SpecificityCefotaxime & Good GoodceftazidimeCefpodoxime Good ModerateCefuroxime Poor PoorCephalexin or Moderate PoorcephradineCefpirome or Poor GoodCefepime Dr.T.V.Rao MD 23
  • Detection of ESBLs: step 2Seek ceph/clav synergy in ceph Risolates Double disc Combination disc Etest Dr.T.V.Rao MD 24
  • Combination discs Disc with Disc withcephalosporin cephalosporin + clavulanic alone acid Dr.T.V.Rao MD 25
  • Dr.T.V.Rao MD 26
  • Etest for ESBLsCefotaximeCefotaxime +clavulanate Dr.T.V.Rao MD 27
  • ESBL – leading cause of Treatment of Failure ESBLs are bacterial enzymes that confer resistance to many highly effective antibiotic classes that can go undetected if conventional testing methods are used in the lab, ultimately leading to treatment failure. Dr.T.V.Rao MD 28
  • Resistance in Gram-negativebacteria: Enterobacteriaceae.The emergence and spread of resistancein Enterobacteriaceae are complicating thetreatment of serious nosocomial infectionsand threatening to create species resistantto all currently available agents.Approximately 20% of Klebsiellapneumoniae infections and 31% ofEnterobacter spp infections in intensivecare units in the United States now involvestrains not susceptible to third-generation Dr.T.V.Rao MD 29cephalosporins
  • The AmpC of E. coliChromosomal, but not Amp: S inducible Amox/clav: SNormally expressed at Piperacillin: S low levels Pip/tazo: SRegulated by a growth Cefoxitin: S rate-dependent Ceftazidime: S attenuation mechanism Ceftriaxone: S Cefepime: SCan become highly expressed with Aztreonam: S mutations Imipenem/meropenem: S Dr.T.V.Rao MD 30
  • ESBLs vs AmpCs ESBLs AmpCsInhibitors (pip/tazo,amp/sulbactam, amox/clav) S RCefoxitin, cefotetan S RCeftazidime, R Rceftriaxone Dr.T.V.Rao MD 31Cefepime S/R S
  • CTX-M-type ESBLsUntil 2000, most ESBL producers were hospital Klebsiella spp. with TEM and SHV mutant β-lactamasesNow, the dominant ESBLs across most of Europe and Asia are CTX-M enzymes, which originated as genetic escapes from Kluyvera sppCurrently recognized as the most widespread andthreatening mechanism of antibiotic resistance, both inclinical and community settings 80% of ESBL-positive E. coli from bacteraemias in the UK and Ireland are resistant to fluoroquinolones 40% are resistant to gentamicin Dr.T.V.Rao MD 32 Livermore, DM J. Antimicrob. Chemother 2009
  • Clinical SignificanceESBL genes are often carried on plasmids thatalso encode resistance to multiple classes ofantimicrobialsAminoglycosides, FluoroquinolonesTrimethoprim /SulphmethoxazoleTreatment experience is largely based onclassical ESBL producersCarbapenemsß-lactam/inhibitor combinations Dr.T.V.Rao MD 33
  • ESBL – K pneumoniaResistance in K pneumoniae to third-generation cephalosporins is typicallycaused by the acquisition of plasmidscontaining genes that encode forextended-spectrum beta-lactamases(ESBLs), and these plasmids often carryother resistance genes as well. ESBL-producing K pneumoniae and Escherichiacoli are now relatively common inhealthcare settings and often exhibit Dr.T.V.Rao MD 34multidrug resistance
  • ESBLs: evolution in detection and reporting Until 2009: Search for ESBL production by specific phenotypic testing- All confirmed ESBL-producers to be reported as RESISTANT to all PENICILLINS, CEPHALOSPORINS and AZTREONAM regardless of MICs Dr.T.V.Rao MD 35
  • Enterobacteriaceae: Breakpoints revised CLSI 2009 CLSI 2010Agent S I R S I RCefazolin ≤8 16 ≥32 ≤1 2 ≥4Cefotaxime ≤8 16-32 ≥64 ≤1 2 ≥4Ceftriaxone ≤8 16-32 ≥64 ≤1 2 ≥4Ceftazidime ≤8 16 ≥32 ≤4 8 ≥16Aztreonam ≤8 16 ≥32 ≤4 8 ≥16Cefipime ≤8 16 ≥32 ≤8 16 ≥32 Dr.T.V.Rao MD 36
  • ESBLs: Evolution in detection and reporting MIC (mg/L) Antibiotic CLSI 2012 CLSI 2012 EUCAST 2012 EUCAST 2012Cefotaxime S≤ R> S≤ R>Ceftriaxone 1 2 1 2Ceftazidime 4 8 1 4Cefepime 8 16 1 4Aztreonam 4 8 1 4 Dr.T.V.Rao MD 37
  • Escherichia coli ESBL+ (CTX-M-1), CLSI 2012 MIC (mg/L)Ampicillin >128 RAmoxi/Clav 32 RPip/Tazo 8S Amikacin 2SCephalotin 32 R Gentamicin 16 RCefotaxime 32 R Ciprofloxacin >32 RCeftazidime 1 S Levofloxacin >32 RCefepime 8SErtapenem 0.12 SMeropenem 0.12 SESBL positive Dr.T.V.Rao MD 38
  • Bacteria not to test for ESBLsAcinetobacters –Often S to clavulanate aloneS. maltophilia –+ve result by inhibition of L-2 chromosomal -lactamase, ubiquitous in the species Dr.T.V.Rao MD 39
  • Other beta-lactamases capable of hydrolyzing expanded-spectrum cephalosporins: Some OXA-type variants (e. g. OXA- 14/17)• AmpC beta-lactamases (e. g. CMY, DHA)• Serine carbapenemases (e. g. KPC)• Metallo-beta-lactamases (e. g. IMP, VIM, NDM Dr.T.V.Rao MD 40
  • Who are At Risk with ESBL+E.coli Travellers 5.2 times more likely to be colonised by ESBL+ E. coliHighest rates of ESBL carriage associated with travels to Africa and Indian subcontinent ESBL+ E. coli had CTX-M All enzymes (71% CTX-M-15, 26% CTX- M-14) Dr.T.V.Rao MD 41
  • Larger Inoculum Effect More vulnerable to hydrolysis of β- lactamaseESBL-KP + 3rd or 4th generation cephalosporinHow about Cephamycins? Little information Dr.T.V.Rao MD 42
  • Role of the Microbiology Lab“ Each laboratory should have a staff member with the time, interest, and expertise to provide leadership in antibiotic testing and resistance. This person would read relevant publications, network with other laboratories, and evaluate potentially useful tests to detect new forms of resistance before new CLSI- recommended tests become available”- Ken Thomson, Emerging Infect. Dis., 2001 Dr.T.V.Rao MD 43
  • ESBL EpidemiologyESBL producers especially prevalent in ICUs andlong term care facilities Becoming more widespread in the community alsoHave been associated with outbreaks Typically arise in ICU Plasmid transfer between GNRs Organism transfer between patients Control of outbreaks Infection control practice – isolation Restriction of 3rd and 4th generation cephalosporins Antimicrobial cycling Dr.T.V.Rao MD 44
  • ESBL are Emerging Challenges in Patient Care for Clinicians and Microbiologists ESBLs: complex evolution since the 1980s (multiple enzymes, High-Risk clones)Now a very major resistance issue in enterics: globally disseminated, ubiquitous (hospital, LTCFs, community), high ratesChallenge of intestinal carriage (intra/inter institutional dissemination, cross-border transmission) and of extra- human reservoirsDetection and reporting issuesTreatment issues Dr.T.V.Rao MD 45
  • Programme Created by Dr.T.V.Rao MD for Microbiologists and Health Care Workers email doctortvrao@gmail.com Dr.T.V.Rao MD 46