Looking for the needle: Glycopepetide Resistance in Staphylococcus aureus

Transcription

1 Looking for the needle: Glycopepetide Resistance in Staphylococcus aureus

2 SA Resistance Penicillin: 1940s, R by 60% Streptomycin: Late 1940s, R developed rapidly Tetracycline: Late 1940s, R after 4yrs Erythromycin: 1952, R developed rapidly By late 1950 s s Multiple R SA Chloramphenicol: Late 1950s, 34% R after 2 years Methicillin: 1960s, 1% by 1970, 42% by 2006 but down to 35% in 2007

3 MRSA Rates

4 Emergence of Vancomycin Resistance Vancomycin introduced in 1950s 1980s increase in use In-vitro R: 1956 study testing activity of new antimicrobials 1990s Daum et al 4 to 8 and 8 to 16 fold increases in MIC seen in 2 strains Biavasco et al - Vanc MICs rose from 2 to 8 in 4 SA strains in single-step step No of strains MIC mg/l 1 2 Vancomycin Initial MIC mg/l No of Transfers Final MIC mg/l Vancomycin (6) (1) 16 (5)

5 Introduced around 1990 Teicoplanin More lipophilic,, better penetration into tissues, phagocyte Can be given I.M. Lower toxicity Early clinical studies showed high failure rate Higher doses used R in-vitro to T achieved more readily than to V Single step fold increase in MIC T Resistance to in SA unknown R found in early 1990s Confusion with V R Rates in 13% UK, >30% France

6 In-vivo Resistance: GISA Location, Strain name, ref. Japan. (Mu50, Hiramatsu, et al., 1997) Limoges, France. (LIM2, 3, Ploy et al., 1999) Michigan, USA. (MI, Smith et al., 1999) New Jersey, USA. (NJ, Smith et al., 1999) Edinburgh, Scotland. (Glasgow 3700 and 3759, Patron et al., 2001) Patient Details Underlying Conditions GISA Prior Vanc Therapy Infection Outcome 4m, Male Post surgery 41 days Sternal wound infection Recovered with ARB+AMP/SUL 2y, Female Leukaemia 10 days CVC-associated bacteraemia 59y, Male DM, ESRD, Ca 18 weeks CAPD peritonitis 66y, Male DM 18 weeks Bacteraemia Recovered with drainage + 10 days Q/D Recovered from peritonitis, died from un-related cause. Recovered from bacteraemia, died from un-related cause. ND Post surgery 20 days ND ND Illinois (St Luke, MMWR, 1999) 63y, female ESRD 25 days Mitral valve endocarditis Minnesota, USA (Fridkin, 2001) 56y, ESRD 18 weeks Vertebral osteomyelitis Los Angeles, USA (Hageman, et al., 2001, Marlowe et al., 2001) Seoul, Korea (Kim et al., 2000) 45y, male metastatic Ca New York, USA (Rotun, et al., 1999, Sieradski et al., 1999) Germany (Anonymous, 1998) Brussels, Belgium (Denis et al., 2000) Brazil (Oliveira, et al., 2001) 27y, female ND 10 weeks Cholangitis 8 days, + 30 days teicoplanin MRSA bacteraemia Died of infection despite VAN + RIF + TOB Infection cleared with VAN+NAF+GEN, but patient died Infection cleared with LIN+TMP/SMX+DOX Died after 2 weeks of VAN+CIP+MTZ 79y, male ESRD 44 days CVC-associated bacteraemia Died of infection 2 patients 1 patient 1 patient 1 patient 1 patient 8y, male 1.5y, male 11y, female 26y female 39y, female post surgery on ITU ND Cystic fibrosis ITU ITU Burns Burns Burns ITU patient Burns ND ND ND ND ND 39 days 32 days 31 days 67 days 74 days Wound sepsis Infection at CVC site Colonising respiratory tract Colonising decubitus ulcer Colonising Colonising Colonising infection not specified infection not specified Both recovered with glycopeptide therapy Resolved without specific therapy ND ND ND Recovered Recovered Recovered Recovered with TMP/SMX Died

7 In-vivo Resistance: hgisa Location, Strain name, ref. Japan. (Mu3, Hiramatsu, et al., 1997) Bristol, UK. (SMH2, Howe, et al., 1999) Patient Details Underlying Conditions hgisa Prior Vanc Therapy Infection 64y, Male Post surgery for lung Ca 12 days MRSA pneumonia 82y, Male ESRD CVC-related bacteraemia Germany (Witte, 2001) 43y, male Alcoholic Nosocomial pneumonia Lyon, France (Bobin-Dubreaux et al., 2001) Hong Kong (Wong et al., 1999) Australia (Ward, et al., 2001) Thailand (Trakulsomboon, et al 2001) Genoa, Italy (Marchese, et al., 2000) Sydney, Australia (Gosbell et al., 2003) Poland (Krzyszton-Russjan et al, 2002) San Francisco, USA (Moore et al., 2003) Outcome Recovered with AMP/SUL + ARB Died of infection after 21 days of VAN No response to 11 days VAN or Q/D. Responded to LIN. 35y, female Nil Nil Conjunctivitis Responded to topical TOB 16 patients 41y, male 68y, female 16y, female 61y, male 62y 58y range from renal failure to lung Ca ESRD, DM, Post bilateral lower limb amputation DM, post knee replacement Nil DM, hepatic cirrhosis Post-pancreas transplant Post lung Ca surgery range from neutropenic sepsis to catheter colonisation 57 days surgical site infection 75 days 14 days Nil 15 days 79y, male Mitral-valve annuloplasty 14 days 45y, male Stomach Ca 41 days, V+21 days T 47y, male IV drug use Nil Surgical site infection Retroperitoneal infection Nosocomial pneumonia Isolated from drainage fluid Chest infection Post operative MRSA bacteraemia+endocarditis ND Community acquired endocarditis, osteomylitis 9 patients Died, others recovered after removal of catheter. No response to 73 days of glycopeptide, resolved with LIN Died Recovered Died Recovered on VAN+CAZ+TMP/SMZ Died Died from pneumonia caused by EC Responded to Q/D treatment Responded to two 6 week courses of V+RIF

8 Vancomycin Non-Susceptible Rates

9 2002, Michigan Emergence of VRSA 40yr Female with hypertension, diabetes mellitus, peripheralvascular disease and chronic renal failure plus haemodialysis Multiple courses of antimicrobial Tx including V Recurrent foot ulcers, metatarsal amputation followed by bacteriaemia Arteriovenous graft for dialysis access replaced by catheter After 6 wks V Tx catheter tip culture positive for MRSA and VRE. MRSA V MIC = 1024mg/L

10 10 reported VRSA Michigan, US (2 clonal types) Pennsylvania, US 2004/7-2 New York, US Iran, 1 Bengal, V MICs = 512mg/L vana Patients: History of MRSA infection or colonisation Several underlying conditions Most received V Tx but not all Patient to patient transfer was ruled out in Michigan

11 V Therapy Failure Clinical Relevance Common - 20% failure in MRSA endocarditis, 40% in LRTI Due to Poor tissue penetration, Slow bactericidal activity or Higher MICs? GISA/hGISA vs. Outcome 226 bacteriaemia cases: Duration of bacteriaemia,, V Tx,, failure to remove source predictors of Tx failure Common factors: underlying disease, medical device, prolonged V Tx Bacteriaemia: : Patients with hgisa are more likely to have high bacterial load, V Tx failure and bacteriaemia >7d (2004) MIC 1 1 : significant risk of vancomycin treatment failure in MRSA bacteriaemia (2004) AUC correlate with failure of V Tx in bacteriaemia (2007) Johnson et al 2003, Scan J Inf Dis 35:782-9 Neoh et al 2007, An Clin Microb Antimicrob 6:13 Charles et al 2004, Clin Inf Dis 38:

12 Clinical Relevance In-vivo/vitro models 2 SA strains in rabbit model: Eradication of pre V Tx strain faster than post Pharmacodynamic model: Mu50 eradicated at same rate as GSSA Outbreaks Perpignan (1999): 12 hgisa, 3 clonal types, no V Tx >3% of MRSA Liverpool 1991:? Patients, 25 strains, same clone Southhampton : 75 teicoplanin R SA T 8mg/L, V 2-4mg/L2 EMRSA 17 Treated successfully with V

13 Resistance Mechanism Scarcity of strains: strain specific traits V Mode of action: Inhibit cell wall synthesis, alter cell membrane permeability and selective inhibition of RNA synthesis Peptidoglycan synthesis:

14 Resistance Mechanism Target D-alaD ala-d-ala 1. Completed PG chain 2. Nascent PG chain 3. Murein monomers in cytoplasmic membrane 1 & 2 - Reduces cross links 3 - Inhibits cell wall synthesis GSSA 20 PG layers hgisa/gisa PG layers

15 GISA Characteristics or Strain Specific Traits Increased PG biosynthesis? PBP2 increase: Found in Mu50/Mu3, results contradictory PBP4 decrease: Found in some GISA/hGISA strains but not others. Less cross links more targets for V GlmS increased activity: Found in Mu50 and Mu3, results unsubstantiated Expression studies No evidence of increased production of PG biosynthesis enzymes

16 GISA Characteristics or Strain Specific Traits Decreased Cell Wall Turnover? Autolysin Atl expression decreased: Found in most GISA/hGISA Reduced Triton induced autolysis rates: All GISA/hGISA except Mu50 & Mu3 No promoter mutation expression reduced

17 GISA Characteristics or Strain Specific Traits No atl promoter mutations Accessory gene regulator (agr( agr) ) defects in some In-vitro mutants and in some GISA/hGISA does not regulate atl expression and not a requirement of GISA/hGISA Other regulators: lytsr, lrgab, arlrs Micro array: contradictory results Mutated grar in Mu50: increased resistance in Mu3 to GISA

18 Mechanism summary Probably decreased cell wall turnover Resistance achieved by different routes Multi step alterations / mutations required for intermediate resistance Mu50 & Mu3 genetically distinct acquired resistance by different route than others in same clonal type

19 Detection Breakpoints: BSAC: V and T 8 / 8 / 4 CLSI (pre 2006): 32 / / 4 CLSI (post 2006): 16 / / 2 GRSA GISA hgisa Typical V MIC > Sakoulas: MIC 1mg/L = V Tx failure Neoh: : AUC correlates to clinical outcome Outcome MIC AUC D to afebrile Poor ± Good ± Sakoulas et al 2004, J Clin Micro 42: Neoh et al 2007, An Clin Microb Antimicrob 6:13

20 Detection in US Breakpoints CLSI (post 2006): 16 / / 2 >300,000 SA from US & Europe