Educational Workshops 2016

Transcription

1 Educational Workshops 2016 Keynote CPE Screening We are grateful to Dr Andrew Dodgson, Consultant Microbiologist, Public Health England and Central Manchester Hospitals NHS Foundation Trust

2 Terminology CPE Carbapenemase Producing Enterobacteriaceae CRE Carbapenem Resistant Enterobacteriaceae CPO Carbapenemase Producing Organism CRO Carbapenem Resistant Organism

3 Classification of carbapenemases Class A (serine based) KPC, GES, SME, NMC, IMI Class B (metallo enzymes) NDM, IMP, VIM, GIM, SIM, SMP, L1, BCII, Ccra Class D (serine) OXA Queenan and Bush, CMR 2007

4 Classification Chromosomal Class A SME, NMC, IMI Plasmid Class A KPC, GES Class B BCII, L1, Ccra Class B NDM, IMP Class D OXA Queenan and Bush, CMR 2007

5 What s worth worrying about? All of them? The Big 5 KPC VIM NDM IMP OXA 48 like

6 Diversity Molecular characteristics Substrate profile Activity against carbapenems Host species. Implications for: Detection Therapy Control? Compare with MRSA

7 Global Distribution KPC From: Lee et al., Front Microbiol Jun 13;7:895

8 Global Distribution NDM From: Lee et al., Front Microbiol Jun 13;7:895

9 Global Distribution OXA 48 From: Lee et al., Front Microbiol Jun 13;7:895

10 htopics/antimicrobial_resistance/data base/pages/map_reports.aspx

11 A UK Perspective Number of isolates referred from UK hospital microbiology laboratories confirmed as carbapenemase producing Enterobacteriaceae by AMRHAI,

12 Klebsiella pneumoniae Carbapenemase (KPC) 1 st described from an isolate in a surveillance project from Plasmid mediated Disseminated throughout eastern seaboard during early 2000 s Rate of carbapenem resistance in K. pneumoniae from NY went from 0.1% to 22% between Yigit et al. Antimicrob Agents Chemother Apr;45(4): Landman et al. J Antimicrob Chemother Jul;60(1):78-82.

13 Control What can we do? Find carriers Screening Isolate carriers Eliminate vectors Hand hygiene Clean equipment Clean environment Change host environment Antibiotic policy

14 Control

15 Screening Who, when & how often? On Admission Any patient who in the last 12 months has: Been an inpatient in a hospital abroad OR Been an inpatient in a UK hospital known to have had problems with spread of carbapenemase producing Enterobacteriaceae OR Previously been colonised or had an infection with carbapenemase producing Enterobacteriaceae or close contact with a person who has, if known 3 screens 48hrs apart

16 MIC s of Carbapenemase producers ECOFF S I R Erta > >1 0.5->64 Imi > >8 0.5->64 Mero > > Miriagou et al. Clin Microbiol Infect Feb;16(2):

17 Detection problems MIC Determined by: Presence, amount & type of carbapenemase Porin loss Presence & amount of other β lactamases (ESBL & AmpC)

18 Detection problems Carbapenem resistance Carbapememase AND Carbapenemase Carbapenem resistance

19 Detection Methodologies Considerations: Clinical sample vs. Screening samples Prevalence Sporadic Outbreak Endemic

20 An approach to clinical samples Test ALL significant Enterobacteriaceae against a carbapenem Ertapenem most sensitive (least specific) Problems with Enterobacter Speciate Work up all showing non susceptibility Don t rely on expert rules of automated systems to identify potential CPE

21 Screening Methods Faecal sample or rectal swab Need adequate sample if rectal swab * (~50% increased positivity rate, for swabs with visibly faecal material, vs without) Enrichment vs. direct Medium? Abx supplemented Mac or CLED Mac or CLED with Carb disc Commercial chromogenic Molecular * Shorten, et al. JHI, 2016.

22 Screening Methods CDC method 10ug Imi disc dropped in to 5ml TSB Overnight incubation Plated on to Mac Comparison of CDC and direct plating on Mac with 10ug Erta disk ( 27mm zone) * CDC, sens 65.6%, spec 49.6% Direct, sens 97.0%, spec 90.5% *Lolans et al, JCM 2010

23 Negative Positive CLED + Erta ESBL Chromogenic + Erta

24 Chromogenic media A number of formulations available Difficult to critically assess performance Likely to be optimised for KPC in particular For example: 302 Turkish Pt s screened (all who were +ve had OXA 48) CDC Method 58% sens, 95% spec chromid Carba 58% sens, 99% spec chromid OXA 48 76% sens, 99% spec. Zarakolu et al., ECCMID 2014

25 Molecular screening methods In House PCR Commercial PCR A number available (Check Direct, EasyPlex, Cepheid) Variations in platform, cost, genes detected. Direct comparisons not available

26 Molecular screening methods Potential advantages Sensitivity Turn around time Genotype known immediately Disadvantages COST Lack of isolate for sensitivity/typing Won t detect novel/unusual mechanisms Equipment/training

27 Molecular screening methods Comparison of commercial PCR vs culture 1 : Sens 96.6%, Spec 98.6%, PPV 95.3%, NPV 99%. Results available in mins. UK experience 2 : 67,801 samples tested by in house or commercial PCR, PCR +ves then cultured Only 81.7% of PCR +ve found to be culture +ve 1 Tato, et al. JCM, 2016, 54(7): Shorten, et al. JHI, 2016.

28 Laboratory Methods Disc susceptibility Interpretation, inoculum. E test Microcolonies, interpretation

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30 Detection Methods BSAC Interpretation, inoculum. E test Microcolonies, interpretation Automated systems (e.g. VITEK) Variable performance, expert rule base may miss some e.g. may not call a carbapenemase unless all ceph s resistant also

31 Confirmatory testing Locally: Is it needed? Is it reliable? Does it make a difference? Clinically? Infection Control?

32 Confirmatory tests Modified Hodge Test Phenotypic Not specific to one enzyme Within the capabilities of most labs Subjective (to a degree)

33 Cloverleaf test

34 Negative MHT

35 Positive MHT

36 Synergy testing Mechanism Carb + clav Carb + boronic acid Carb + EDTA R to temocillin MBL +++ +/ KPC +/ +++ +/ OXA

37 Confirmatory testing PCR Gold standard Reference test Commercial systems available Recently published comparison no difference in performance between 3 commercial assays Findlay et al., JAC, 2015; 70(5):

38 An unanswered question Can we robustly determine loss of carriage? Do we rescreen patients known to be previously positive when readmitted? What does a negative mean? Genuine or below limit of detection? PCR more believable than culture?

39 Summary CPE represent a heterogenous group of species and mechanisms Laboratory detection from clinical specimens may require a high index of suspicion No one screening method will tick ALL the boxes