Old bugs - new tricks Microbiology of UTIs in Dr Tim Collyns Consultant Microbiologist Leeds Teaching Hospitals NHS Trust

Transcription

1 Old bugs - new tricks Microbiology of UTIs in 2010 Dr Tim Collyns Consultant Microbiologist Leeds Teaching Hospitals NHS Trust

2 Microbiological aetiology of UTIs Collateral damage associated with antibiotics Available therapeutic options in an era of increasing resistance

3 Urinary tract infections (UTI): Simple vs complicated Lower vs upper Community acquired vs hospital acquired Healthcare associated. Initial episode vs recurrent Species distribution not changed (antimicrobial resistance pattern increasing) Symptomatic UTI vs asymptomatic bacteriuria Urinary catheters WILL become colonised

4 Uncomplicated UTIs (cystitis) ARESC Study: Antimicrobial Resistance Epidemiological Survey on Cystitis. Female patients, Nine European countries and Brazil, > 4200 enrolled. Schito 2009.

5 Organism % Escherichia coli 76.7 Klebsiella pneumoniae 3.5 Proteus mirabilis 3.4 Staphylococcus saprophyticus 3.6 Other uropathogens 7.6 Enterobacteriaceae (Enterobacter, Citrobacter, Serratia, Klebsiella, Pantoea, Salmonella spp, M morganii) Other Gram negatives (incl. Pseudomonas aeruginosa 0.2%) Enterococci Others 5.1 S aureus, coagulase negative staphylococci, streptococci

6 Pathogen distribution by country (W Europe) after Schito 2009 Country Total (%) E coli K pneu P mira S sapr Uropath Others France 488 (16.2) 409 (83.8) N/lands 36 (1.2) 29 (80.6) Spain 650 (21.5) 515 (79.2) Germany 317 (10.5) 243 (76.7) Italy 329 (10.9) 239 (72.6) Austria 91 (3.0) 62 (68.1) Western Europe (78.3) 5 (1.0) 15 (3.1) 21 (4.3) 21 (4.3) 17 (3.5) 1 (2.8) 0 (0) 2 (5.6) 2 (5.6) 2 (5.6) 15 (2.3) 28 (4.3) 29 (4.5) 38 (5.9) 25 (3.8) 8 (2.5) 15 (4.7) 9 (2.8) 19 (6.0) 23 (7.3) 18 (5.5) 10 (3.0) 0 (0) 44 (13.4) 18 (5.5) 5 (5.5) 3 (3.3) 2 (2.2) 12 (13.2) 7 (7.7) 52 (2.7) 71 (3.7) 63 (3.3) 136 (7.1) 92 (4.8)

7 E coli...know thine enemy

8 E coli

9 E coli, Blood Agar plate

10 E coli, MacConkey plate (Lactose fermenter)

11 E coli Certain serogroups predominate O1, O2, O4, O6, O7, O8, O75, O150, O18ab Uropathogenic E coli clones Certain serotypes more virulent Cystitis or pyelonephritis Adhesins epithelial cell receptors P fimbriae: globoseries glycosphingolipids type I fimbriae S/FIC fimbriae G, M fimbriae Sobel, Kaye 2010

12 Recurrent / structural abnormalities Hospital / longterm healthcare facilties: Increased proportion due to Proteus, Pseudomonas, Klebsiella, Enterobacter Enterococci, staphylococci (non S saprophyticus) Historically greater antibiotic resistance Intrinsic (enterococci, staphylococci, Pseudomonas) Cross-infections with resistant isolates (catheter associated)

13 Treatment Usually only if symptomatic (Nonspecific therapy hydration) Antimicrobials: Serum / tissue / urine concentration of agent Site of infection Lower (cystitis) upper (pyelonephritis) - bacteraemia (Renal insufficiency urine concentration) Organism in vitro susceptibility

14 Available classes (for Gram negative bacteria) β-lactams: Penicillins (e.g. ampicillin, amoxicillin, piperacillin; +/- β-lactamase inhibitor) Cephalosporins (oral / intravenous) Monobactam - aztreonam Carbapenems (intravenous, currently) Quinolones Aminoglycosides (intravenous / intramuscular) Trimethoprim / co-trimoxazole Nitrofurantoin Tetracyclines

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16 Susceptibilities of E col isolates Schito 2009 Antimicrobial % Sensitive (No.) Intermediate Resistant Ampicillin 45.1 (1045) 6.6 (153) 48.3 (1117) Co-amoxiclav 82.5 (1910) 13.7 (316) 3.8 (89) Mecillinam 95.8 (2215) 1.5 (34) 2.8 (6.4) Cefuroxime 82.4 (1907) 15.2 (353) 2.4 (55) Ciprofloxacin 91.7 (2120) 0.2 (5) 8.1 (187) Co-trimoxazole 70.6 (1633) 3.1 (72) 1.6 (38) Nitrofurantoin 98.1 (2272) 1.3 (30) 0.6 (13)

17 Susceptibilities of E col isolates Schito 2009 Country AMP CO-A MEC CXM CIP COT NIT Austria France Germany Italy Spain N/lands Brazil

18 E coli bacteraemias, 2008, United Kingdom Agent Susceptible % Health Protection Agency Intermediate Resistant 95% CI Non-sus 95% CI Amoxicillin Co-amoxiclav Ciprofloxacin Cefotaxime Gentamicin Meropenem Piperacillin- Tazobactam

19 Figure 3 Antibiotic susceptibility for E. coli bacteraemia reports, England, Wales and Northern Ireland, *

20 Table 2. Antibiotic susceptibility data for reports of E. coli bacteraemia, England, Wales and Northern Ireland: * E. coli Total reports: 18,593 19,987 22,128 23,971 25,532 % Nonsusceptible Cefotaxime 9% 11% 12% 11% 10% Ceftazidime % Nonsusceptible 9% 12% 12% 11% 10% Ciprofloxacin % Nonsusceptible 19% 23% 23% 21% 20% Gentamicin % Nonsusceptible 8% 9% 9% 8% 8% Imipenem % Nonsusceptible 0% 0% 0% 0% 0% Meropenem % Nonsusceptible 0% 0% 0% 0% 0%

21 β-lactam resistance in Enterobacteriaceae: Enzyme mediated: β-lactamases (Ancient heritage: > 2 billion years old) Serine residue active site; or metalloenzymes (Zinc ion) Inherent gene carried on bacterial chromosome De-repressed : e.g. Enterobacter, Citrobacter species Acquired transmissible genetic elements: plasmids E.g. Klebsiella pneumoniae, E coli Vary in ability to hydrolyse different β-lactams: Some drug structures more resilient than others. Some blocked by β-lactamase inhibitors clavulanic acid (co-amoxiclav), tazobactam (with piperacillin) Various classifications / name derivations

22 3 letter monikers for families: SHV (>50): Variable response to sulfhydryl inhibitors TEM (>130): After patient (Temoneira) CTX-M (>40), OXA, IMP: Ability to hydrolyse cefotaxime, oxacillin, imipenem VIM: Verona integron encoded metallo-β-lactamase KPC: Klebsiella pneumoniae carbapenemase NDM: New Delhi metallo-β-lactamase Jacoby 2005;

23 NDM-1: First detected United Kingdom January Now predominant carbapenem-hydrolysing enzyme in Enterobacteriaceae in UK (44% 2009) : 37 isolates K pneumoniae (21), E coli (7), Enterobacter spp (5), Citrobacter freundii (2), Morganella (1), Providencia (1) 29 patients 15 in urine ESBLs widespread in India, NDM-1 also in isolates in north & south India Links between many of the UK patients and India Kumaraswamy 2010; HPA

24 37 isolates; % susceptible Imipenem 0 Meropenem 3 Piperacillin-tazobactam 0 Cefotaxime 0 Aztreonam 11 Ciprofloxacin 8 Gentamicin 3 Amikacin 0 Minocycline 0 Tigecycline 64 Colistin 89 (Morganella, Providencia: Intrinsic R)

25 Antibiotics downsides include Allergic reactions penicillin Intolerance / GI side-effects. Other adverse effects: Aminoglycosides: nephrotoxicity, ototoxicity Administration e.g. if intravenous only. Cost Collateral damage Secondary infections Meticillin resistant S aureus, C difficile, GREs, Candida Induction of resistance Individual infecting organism Circulating bacterial flora

26 MRSA Fluoroquinolones (e.g. Ciprofloxacin). MRSA usually resistant to fluoroquinolones Good skin tissue penetration / excreted in human sweat: Loss of colonisation resistance by normal skin flora In vitro: Induction of fibronectin binding proteins Increased adhesion by quinolone resistant S aureus Bisognano 2000, Paterson 2004,

27 Univariate analysis, antimicrobials pre MRSA / MSSA infection Graffunder 2002 Preceding Antimicrobial MRSA (%) MSSA (%) OR (95% CI) P value β-l / β-li (1.4, 3.6) <0.001 Levofloxacin (3.4, 15.4) <0.001 Aminoglycoside (2.4, 25.3) < st gen ceph (0.87,1.7) rd gen ceph (0.63,6.6) 0.25 Carbapenems (0.89,5.7) 0.04 Co-trimoxazole (1.3, 15.1) 0.01

28 Multiple logistic regression analysis, factors associated with MRSA infection Risk factor OR 95% CIs P value Levofloxacin , 20.3 <0.001 Macrolides , Enteral feeding , Surgery , Previous hospitalisation , LOS before culture , Graffunder 2002

29 Clostridium difficile Antibacterials: Loss of normal colonic microflora colonisation resistance : C difficile spore germination, multiplication, toxin production diarrhoea / worse sequelae 2 nd & 3 rd generation cephalosporins (cefuroxime, cefotaxime, ceftazidime) Clindamycin Fluoroquinolones: Certain strains: e.g. PCR ribotype 027.

30 Choice of treatment Paradox Severe sepsis: Getting it right first time Preserving antimicrobial efficacy De-escalation

31 Improve diagnostic speed Aetiology; in vitro susceptibilities Bacteriological methods long-standing, but: Direct to specimens: PCR / NAAT blood, sterile sites Organism identification: MALDI-TOF Matrix-Assisted Laser Desorption Ionisation Time of Flight Mass Spectroscopy: bacteria / yeasts Rapid automated sensitivity testing (< 12 hours)

32 Less familiar agents (...in United Kingdom)

33 Mecillinam Beta lactam (6-β-amidinopenicillanic acid) Pivmecillinam Pivaloyloxymethyl ester: Much more active vs Gram negatives (binds to PBP2) (Enterococci resistant, S saprophyticus may be inhibited) Enterobacteriaceae Usual suspects more tricky: P aeruginosa, Acinetobacter spp, anaerobes: resistant Serratia marcescens: usually resistant M morganii, Providencia spp may be sensitive (Paradoxical effect with P stuartii) P mirabilis, P vulgaris: usually sensitive

34 Uses: Urinary tract infections Lower (Upper step down oral therapy). ((Other MDR coliforms: e.g. Biliary)) Advantages: High % still susceptible (> 90% global) Widely used in Scandinavia, >20 years, still high susceptibility Low C difficile propensity (Baines 2009: low risk in in vitro human gut model) Avoid if penicillin allergy (tho hypersensitivity reactions uncommon) Kahlmeter 2003, Wootton 2010

35 E coli, 3 rd generation cephalosporin resistant: % susceptible (Wootton 2010) Mecillinam 100 (93.5% local CPD R) Meropenem 100 Cefotaxime 13.3 Amoxicillin 0 Co-amoxiclav 0 Piperacillin-tazobactam 53.3 Ciprofloxacin 40 Nitrofurantoin 76.7 Trimethoprim 30 Gentamicin 53.3

36 Mastascan plate evaluation (LTHT) Breakpoint plate, 8 mg/l [BSAC cut-off]. +/- testing by current disc method: All if resistant, subset of those sensitive Gram negative isolates tested. Overall susceptible: 1147 (96%) Norris (unpubd)

37 Temocillin 6-α-methoxy derivative of ticarcillin Active vs Gram negative bacilli (excl P aeruginosa) Stable vs many β-lactamases: SHV, TEM, CTX-M families, also AmpC Stable to some carbapenemases Carbapenem-sparing agent, intravenous: UTIs due to ESBL producing Enterobacteriaceae Ecologically benign : Low propensity for C difficile Livermore 2009.

38 E coli, Gram negative

39 Other old drugs: Colistin Iv fosfomycin

40 Conclusions: E coli remains predominant UTI pathogen. Increasing problems of resistance, globally Recognition of collateral damage of antibiotics Fluoroquinolones & MRSA Severe sepsis: Getting it right first time...but deescalation Carbapenem sparing agents Old drugs being revived / re-visited Mecillinam, temocillin. Shortage of new antibiotics for Gram-negatives:...avoid antibiotics unless clear clinical indication

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