2. Vancomycin Resistant Enterococci Department of Internal Medicine Kyung Hee University Medical Center MS Lee M.D. MS Lee M.D.

3. Contents Mechanism of vancomycin resistance Clinical significance of VRE Treatment of VRE infection Prevention & Infection control of VRE

4. Vancomycin Resistance S Van MIC  4 ug/mL I 8-16 ug/mL R  32 ug/mL by CLSI guidelines (Clinical Laboratory Standards Institute)

5. Vancomycin from Streptomyces orientalis, 1956 Spectrum : narrow, aerobic G (+) organisms Indication - S. aureus infections - Coagulase negative staphylococcal infections - S. pneumoniae infections - C. difficile colitis - Others : Enterococci, Corynebacterium JK Mechanism of action - Inhibit cell wall synthesis - Change penetration of cell membrane

6. Peptidoglycan D-Ala D-Glu D-Ala D-Glu D-Ala NAMNAG D-Ala D-Glu D-Ala NH3 - NAMNAGNAMNAG NAG : N-acetylglucosamine, NAM : N-acetylmuramic acid

7. D-Ala D-Glu D-Ala D-Glu D-Ala NAMNAG D-Ala D-Glu D-Ala NAG D-Ala D-Glu D-Ala NAMNAGNAMNAGNAM D-Glu NAG Function of PBP

8. D-Ala D-Glu NAMNAG D-Ala D-Glu D-Ala NAMNAG D-Ala D-Glu D-Ala NAGNAMNAGNAMNAGNAM

9. Peptidoglycan Structure

10. Mechanism of antimicrobial resistance in S. aureus Beta-lactamase Extra PBP ( PBP2A) PBP Beta-lactams

11. D-Ala D-Glu D-Ala D-Glu D-Ala NAMNAG D-Ala D-Glu D-Ala NAG D-Ala D-Glu D-Ala NAMNAGNAMNAGNAM D-Glu NAG Mechanism of action of vancomycin vancomycin

12. Vancomycin Resistance - Intrinsic : Leuconostoc, Pediococcus Lactobacillus, group G streptococci Erysipelothrix, etc - Acquired : no problem until 1990’s VRE (1986, UK) VISA (1996, Japan)

13. Vancomycin resistance in Enterococci Resistance phenotype 6 types : VanA, VanB, VanC, VanD, VanE and VanG Can be distinguished on the basis of the MIC level, inducibility and transferability of resistance to glycopeptides (vancomycin, teicoplanin) Interpretation of MIC Vancomycin : S (0.5-4.0 ug/mL), low R (8-32), high R (  32) Teicoplanin : S (< 2.0 ug/mL), R (  4)

14. Glycopeptide Resistant Enterococci

15. VanA type VRE D-ala-D-lactate : synthesis of modified precursors - Decreased affinity for vancomycin & teicoplanin - PG precursor has D-lactate(-hydroxyacid) instead of the second D-alanine - Vancomycin binds 1,000-fold less tightly to D-alanyl-D- lactate than to D-ala-D-ala  bacteria to survive 1000- fold higher concentrations of vancomycin Tn1546 : “vanA gene cluster” on the transposon, or “jumping” genetic element

16. Glycopeptide resistance transposon Tn1546 from plasmid pIP816 on E. faecium BM4141 ORF2 vanR vanS vanH vanA vanX vanY vanZ ORF1 transposase resolvase response regulator histidine protein kinase dehydrogenase ligase dipeptidase D, D-carboxypeptidase Unknown IR L IR R TranspositionRegulation Glycopeptide resistance Accessory proteins

17. VanB type VRE Genotypic classification & Mechanism of resistance l vanB gene - E. faecalis V583, composite transposon Tn1547 - Transfer of large (90-250 kb) genetic elements from chromosome to chromosome - Homology (76%) to the vanA gene - Gene cluster : vanR B, vanS B, vanH B (dehydrogenase), vanB (ligase), vanX B (D, D-dipeptidase), vanY B, vanZ (-) - Resistance is not induced by teicoplanin

18. VanC, VanD type VRE vanC gene E. gallinarum(C1), E. casseliflavus(C2), E. flavescens(C3) Low level R to vancomycin, S to teicoplanin Pentadepsipeptide terminate in D-Ala-D-Ser vanD gene Some E. faecalis, E. faecium Moderate R to vancomycin, low R or low S to teicoplanin

20. Contents Mechanism of vancomycin resistance Clinical significance of VRE Treatment of VRE infection Prevention & Infection control of VRE

21. Enterococci Low virulent G (+) cocci, normal flora in the GI tract - sometimes improve without treatment Opportunistic pathogens in the immunocompromised Pts. 12% of nosocomial bacterial infection (4th  2nd pathogen, 1990~1992, USA) Clinical manifestations UTI : the most common infection (62%) Wound infection : abdominal or pelvic site (25%) Bacteremia (10%), endocarditis, etc

22. Enterococcal species Predominant human pathogen E. faecalis (higher frequency, 85~90%) E. faecium (more significant d/t higher resistance) Occasional human isolates E. durans, E. avium, E. casseliflavus, E. gallinarum, E. hirae, E. mundtii, E. raffinosus, E. flavescens No known about of human infections E. malodoratus, E. pseudoavium, E. sulfureus, E. cecorum, E. columbae, E. saccharolyticus, E. dispar, E. seriolicida, E. solitarius

23. Antimicrobial resistance in Enterococci Intrinsic resistanceAcquired resistance  -lactams (relatively high MICs) Tetracyclines Aminoglycosides (low level)Macrolides Lincosamides (low level)Lincosamides (high level) TMP/SMX (in vivo)Chloramphenicol Aminoglycosides (high level) Vancomycin Penicillin (  -lactamase) Quinolones Cell wall active agents (tolerance) Ampicillin or Vancomycin  Aminoglycoside

24.  Predominantly of GI tract  Does not result in symptoms  Last for long periods - spontaneous decolonization in 34%, infrequently - able to persist more than 6 months - pharmacological method to eliminate VRE : limited success (oral bacitracin, ramoplanin, novobiocin)  A reservoir for the transmission of VRE - capable of prolonged (>1 wk) survival in the environment - can be transferred from environmental sites to staff hands - despite of contact precaution, HCWs spread VRE from a contaminated to an uncontaminated part of a pt’s room in nearly 1 in 10 encounters VRE colonization VRE

25.  Usually develops in pts colonized VRE - the ratio of infected-to-colonized pts : dependent on the specific patient population highest in hematology pts, organ transplant - portal of entry : urinary tract intra-abdominal (GI tract, biliary tree) pelvic sources wounds (surgical wounds, decubitus ulcers) intravascular catheters VRE infection VRE

26. Risk factors of colonization/infection - often multiple factors involved - the role of predominant factors is difficult to elucidate Being critically ill Severe underlying disease Immunosuppression (esp. oncology or transplant wards) Renal insufficiency Undergoing intra-abdominal or cardiothoracic surgical or other invasive procedures Having an indwelling urinary or central venous catheter Prolonged hospital or intensive care unit stay VRE

27. Very old or very young Multiple antimicrobial therapy : 3rd generation cephalosporin, clindamycin, imipenem, amikacin, metronidazole,  vancomycin Clostridium difficile infection Care by the colonized staff The presence of mucositis, fecal incontinence,  diarrhea The receipt of selective bowel decontamination, sucralfate,  enteral feedings Risk factors of colonization/infection VRE

28. Mortality VRE > 50% (range 8~73%) VRE vs. VSE bacteremia (48.9% vs. 19%, p= 0.007) attributable mortality : 30% VRE seems to more often cause life-threatening diseases than do VSE VRE played a critical role in the higher recurrence of bacteremia, in the associated mortality, and excess cost Infect Control Hosp Epidemiol 2003, 24(9):690-8 VRE

29. Epidemiology - Europe 1st isolate of VRE : 1986, UK Low incidence of VRE infection in hospital Normal flora in healthy person in community - colonization rate (12~28%) - due to contamination of food chain by avoparcin used as animal feed supplement VRE

30. Epidemiology – U.S. Nosocomial pathogen of 1990s : US 0.3% (1989)  7.9% (1993)  15.4% (1997) in the ICU, 0.4%  13.6%  23.2% 9.5% co-colonization/co-infection with MRSA Rectal colonization rates of hospitals : 20~53% Outbreak by one or different types Intra/inter-hospital transfer by different types ’96 VRE Infect Control Hosp Epidemiol 2004, 25:99-104

31. Epidemiology - Korea 1st VRE isolate in Korea : vanA E. durans, 92’ Colonization rate in tertiary hospital : 8.1% %, AMC data - 1st VRE : Mar. 97’, wound, MICU  64 strains - Point surveillance (98’) : VRE of inpatient : 212 (26, 12.3%), vanC-1, E. gallinarum VRE

32. How many VREs are in KHMC?

33. VRE in KHMC Resistance (%) 12.7 % 20.7 % 21.6 % 22.0 %

34. VRE in KHMC 33.0 % 41.8 % 39.6 % 47.2 %

35. 2006 VRE in KHMC E. faecalisE. faeciumE. gallinarumE. casseliflavus Total417 (56.6%)299 (40.5%)10 (1.4%)11 (1.5%) VRE16 (3.8%)141 (47.2%)0 (0%)5 (45.5%) UrineBloodStoolWound Total408 (55.4%)72 (9.8%)41 (5.6%)33 (4.5%) VRE94 (23.0%)9 (12.5%)40 (97.6%)13 (39.4%) n by Species n by Sites

36. Clinical issues of VRE The lack of effective antimicrobial therapy May persist for a long time and serves as a reservoir for transmission of VRE to other patients The possibility that vancomycin-resistant genes can be be transferred to other G (+) bacteria, esp. S. aureus, coagulase-negative staphylococci, S. pneumoniae, and Corynebacterium spp. : Conjugative transfer of the vanA gene from Enterococci to S. aureus has been demonstrated in vitro & in vivo

37. Contents Mechanism of vancomycin resistance Clinical significance of VRE Treatment of VRE infection Prevention & Infection control of VRE

38. Treatment of VSE Localized infection : penicillin (PCN), ampicillin Severe infection (bacteremia, endocarditis, etc) - AG high resistance (  )  PCN, ampicillin  AG AG high resistance (  )  high dose ampicillin glycopeptide streptomycin  penicillin teicoplanin  ciprofloxacin

39. Treatment of VRE infection Old antimicrobial agents VRE with susceptibility to PCN, ampicillin, AG, teicoplanin Chloramphenicol (57% of pt. effective) - not bactericidal, side effect, resistance  Fosfomycin, nitrofurantoin, sodium fusidate, novobiocin, etc Chlorhexidine, povidone-iodide : antiseptics

40. Current new agents FDA approved for VRE infection Quinupristin-dalfopristin (synercid) l Oxazolidinone (zyvox) Promising? l Lipopeptides (Daptomycin) l Glycylcycline (Tigecycline) l new glycopeptide : mannopeptimycin, dalbavancin

41. Synercid Quinupristin-dalfopristin - 1st FDA approved agent to VRE faecium (Sep, 99’) - 1st IV available streptogramine agents : similar to macrolide, lincosamide (*MLS B group) - Pristanamycin ; quinupristin, dalfopristin (30:70) from Streptomyces pristinaspiralis if single form  bacteriostatic combined  bactericidal to G(+) cocci (  8-16 times) M. catarrhalis, H. influenzae, Legionella Mycoplasma, Chlamydia, anaerobes

42. Synercid Mechanism of action - Irreversible inhibition of protein synthesis by block 50s ribosome (Q-Ribosome-D, 1:1:1) - Synergy (-) with GM, AMP, RIF, Quinolone - Cross resistance (-) to quinolone, glycopeptide, aminoglycoside,  -lactam - Half-life < 1h, but long post antibiotic effect (2.6~8.5h)  7.5 mg/kg q 8hr, hepatic metabolism & fecal excretion - Cannot be penetrate placenta, BBB

43. Mechanism of action Synercid

44. Antibacterial spectrum & Potency OrganismMIC 90 (ug/mL) S. aureus methicillin susceptible1 methicillin resistant2 S. epidermidis methicillin susceptible1 methicillin resistant1 Other CoNS0.5-1 S. pneumoniae penicillin susceptible1 penicillin resistant1 erythromycin susceptible1 erythromycin resistant1 OrganismMIC 90 (ug/mL) S. agalactiae0.25 S. pyogenes0.5 viridans streptococci0.5 E. faecium vancomycin susceptible1 vancomycin resistant1 E. faecalis vancomycin susceptible32 vancomycin resistant32 Synercid

45. Dosage & Administration  Only IV forms available  VREF infection : 7.5 mg/kg IV q 8hr Complicated SSTI : 7.5 mg/kg IV q 12hr  Duration of therapy : SSTI - 7 days, depends on the severity of infection In KOREA : 7~14 days  Pregnancy category B (? Safe under 16 year old)  Dilution with at least 5% DW 250 mL (not NS) Infusion over 1 hr via central line d/t phlebitis Flushing before or after infusion with 5% DW when pph infusion

46. Adverse effects Adverse eventQ/DComparator Venous reaction (ONLY when pph infusion) Inflammation at infusion site42.025.0 Pain at infusion site40.023.7 Edema at infusion site17.39.5 Infusion site reaction13.410.1 Thrombophlebitis2.40.3 Non-venous reactions Nausea4.67.2 Diarrhea2.73.2 Vomiting2.73.8 Rash2.51.4 Headache1.60.9 Pain (arthralgia/myalgia)1.50.1 * Pruritus1.51.1 * P <0.001

47. (S)-N-[[3-[3-Fluoro-4-(4-morpholinyl)phenyl]-2-oxo-5-oxazolidinyl] methyl]-acetamide Empirical formula : C 16 H 20 FN 3 O 4 Molecular weight : 337.35 Approved by FDA in Apr., 2000 LINEZOLID (Zyvox ® ) Chemical Structure

48. Mechanism of action of Zyvox fMet-tRNA : N-formylmethionyl-tRNA

49. OrganismMIC 50 MIC 90 Overall S. aureus (n=2256) oxacillin susceptible1-4 0.5-8 oxacillin resistant1-4 0.5-8 Coagulase-negative staphylococci (n=48) oxacillin susceptible0.5-21-40.25-4 oxacillin resistant0.5-21-20.5-4 β-hemolytic streptococci (n=47)1-22-41-4 S. pneumoniae (n=454) penicillin susceptible0.51<0.016-1 penicillin resistant0.5-110.06-4 Enterococcus spp (n=980) vancomycin susceptible1-4 0.5-4 vancomycin resistant2-4 1-4 Antibacterial spectrum & Potency of Linezolid

50. Bacteriostatic or Bactericidal??  Generally bacteriostatic  Only bactericidal to B. fragilis, C. perfringens, some Streptococci including S. pneumoniae  No additive or synergistic effect when combination with aminoglycosides  Some reports, bactericidal in vivo : maintain the high concentration in serum & tissue : inhibition of bacterial toxin & virulence factor production : stimulation of neutrophil phagocytosis

51. Dosage & Administration PO = IV (oral bioavailability : 100%) In mild or uncomplicated infection : 400 mg bid In severe infection : 600 mg bid Children : 10mg/kg bid Duration of therapy Pneumonia or SSTI : 10-14 days VRE infection : 14-28 days MRSA infection : 7-28 days Dosage modification : Not in hepatic/renal insufficiency Excretion : Liver 70%, Kidney 30% Excellent penetration to skin, soft tissue, lung, heart, intestine, liver, kidney, CSF

52. Adverse effects Overall incidence : 3~4% Diarrhea (8.3%), Headache (6.5%), Nausea (6.2%), Vomiting (3.7%), Others : insomnia, dizziness, rash Lab : Thrombocytopenia (2.4%) most likely to occur after prolonged use (> 2 weeks) Others : anemia, leukopenia,  liver enzymes/bilirubin Pregnancy category C

53. Daptomycin (cubicin ® ) cyclic lipopeptide fermentation of Streptomyces roseosporus - disrupt multiple aspects of bacterial membrane function - FDA approved for complicated SSTI at 03’ waiting for endocarditis not for pneumonia - non FDA approved indication for VRE

54. Daptomycin aerobic & anaerobic gram (+) pathogens including VRE, synercid/linezolid-RE, VISA PK/PD - synergy with AG, rifampicin in vitro - rapid concentration-dependent bactericidal activity - long post antibiotic effect - low drug resistance - dose : 4 mg/kg iv q 24h (half-life : 8 h) - excrete via kidney  adverse reaction - increased CPK : reversible - GI trouble

55. In vitro activity of daptomycin to gram positive organisms

56. Tigecycline (tygacil ® ) semisynthetic glycycycline - tetracycline + glycylamido moiety - FDA approval for SSTI & intra-abdominal infection (Jun, 05’) - broad spectrum : aerobic & anaerobic G (+), G (-) - not for VRE infection

57. Tigecycline Mechanism of action - inhibition of protein synthesis : 30s ribosome bind - glycylamido moiety render avoidance from ribosomal protection, efflux - bacteriostatic  Characteristics - high tissue penetration - dose : 100 mg iv loading  50 mg iv q 12h over 0.5-1h - excretion : biliary/fecal (59%), kidney (33%) - if severe hepatic dysfunction  25mg iv q 12h - adverse reaction : nausea (25.9%), vomiting (19.7%)

58. Antimicrobial spectrum of tigecycline

59. Contents Mechanism of vancomycin resistance Clinical significance of VRE Treatment of VRE infection Prevention & Infection control of VRE

60. Prevention & Control Standard principles Restriction of antimicrobial agents Monitoring of VRE isolation from clinical specimens Analysis of VRE genotype Isolation for VRE-infected/colonized patients Hand washing, gown & glove use before and after patient contact Inpatient surveillance

61. Prevention & Control Restriction of antimicrobial agents Hospital antibiotic formulary restriction - The only control measure with proven effectiveness to control resistance related to antibiotic use - Low resistance potential agents are preferred than (eg. cefepime, levofloxacin, meropenem, clindamycin, metronidazole, doxycycline, minocycline, linezolid, oral cephalosprorins) High resistance potential (eg. ceftazidime, ciprofloxacin, imipenem ) Vancomycin should be restricted Not because increase enterococcal strains, But increase it selects out naturally resistant enterococcal strains Clin Infect Dis 2003:37(7);875-81, Cunha BA

62. Appropriate Glycopeptide Use Serious infections due to  -lactam-resistant gram (+) organisms Serious infections in  -lactam allergic patients C. difficile colitis unresponsive to metronidazole Endocarditis prophylaxis, according to AHA guidelines Single-dose surgical prophylaxis [for high-risk of MRSA ]

63. Prevention & Control Contact precaution & Hand washing Most effective method & basis of intra-hospital transfer control Clean, non sterile gloves & gowns should be worn when entering the room of VRE infected or colonized patients The hand should be washed with antiseptic soaps or waterless antiseptic agents before and after contact with VRE patients  VRE colonization/infection 12 cases/1,000 patients-day after hand-washing  3 cases/1,000 patients-day Infect Control Hosp Epidemiol 2006, 27(10):1018-21

64. Prevention & Control Isolation The patients who were VRE colonized or infected should be placed in a private room and have dedicated patient care items until 3 consecutive negative stool cultures with 1 wk interval Problem Availability of isolation : private room, cost, compliance Prolonged intestinal colonization of VRE Long survival of VRE on inanimate environment