Educational WorkshopEW01: Antimicrobial susceptibility testingarranged with the European Committee on Antimicrobial Susceptibility Testing (EUCAST)

Convenors: Gunnar Kahlmeter (Vaxjo, SE) ( j , )Derek Brown (Peterborough, UK)

Faculty: Derek Brown (Peterborough, UK)y ( g , )Gunnar Kahlmeter (Vaxjo, SE)Johan Mouton (Nijmegen, NL)Alasdair MacGowan (Bristol, UK; nopresentation submitted)presentation submitted)Rafael Canton (Madrid, ES)

Brown - EUCAST definitions

EUCAST definitions(and breakpoint table MIC and(and breakpoint table, MIC and

zone distribution website conventions)

Derek BrownECCMID 2011, Milan

Breakpoints and cut-off values

• Clinical breakpoints

Non species related breakpoints• Non-species related breakpoints

• Epidemiological cut-off value (ECOFF)

Clinical breakpoints

• Values that correlate with clinical outcome

• MICs are the primary breakpoints

• Breakpoints in other methods are related to MIC breakpoints

3

Brown - EUCAST definitions

Clinically susceptible

A microorganism is defined as susceptible by a level of antimicrobial activity associated with a high likelihood of therapeutic successtherapeutic success

• a microorganism is categorized as susceptible (S) by applying the appropriate breakpoint in a defined phenotypic test system

• this breakpoint may be altered with legitimate changes in circumstances

Clinically resistant

A microorganism is defined as resistant by a level of antimicrobial activity associated with a high likelihood of therapeutic failure.

• a microorganism is categorized as susceptible (S) by applying the appropriate breakpoint in a defined phenotypic test system

• this breakpoint may be altered with legitimate changes in circumstances

Clinically intermediateA microorganism is defined as intermediate by a level of antimicrobial agent activity associated with uncertain therapeutic effect.

• It implies that an infection due to the isolate may be appropriately treated in body sites where the drugs are physically concentrated or when a high dosage of drug can be used;

• it also indicates a buffer zone that should prevent small, uncontrolled, technical factors from causing major discrepancies in interpretations.

4

Brown - EUCAST definitions

Non-species-related breakpoints• Pk/Pd (pharmacokinetics/ pharmacodynamic)

breakpoints• Calculated by statistical techniques (e.g. Monte

Carlo simulation) to estimate the probability of attaining the target value of the relevant Pk/Pd index for microorganisms with different MICs

• Used in clinical breakpoint development and in situations where a breakpoint may be required but there is no species-specific breakpoint

• Clinical breakpoints will be same unless they split the wild type or there is no resistance

Epidemiological cut-off value (ECOFF)

• MIC value identifying the upper limit of the wild type population

• A microorganism is defined as wild type (WT) for a species by the absence of acquired and mutational mechanisms of resistance to the agent.

EUCAST wild type and ECOFF

Wild type

ECOFF

5

Brown - EUCAST definitions

EUCAST wild type and ECOFF

Wild type

ECOFF

Epidemiological cut-off values (ECOFFs)

• Estimated by visual inspection or statistically calculated (Turnidge et al CMI 2006;12:418-25)

• The ECOFF is not changed by samplingThe ECOFF is not changed by sampling time, source (human, animal, environmental), geographical origin

• Used in clinical breakpoint development and as a sensitive indicator of resistance development in surveillance studies.

There is no definite relationship between the ECOFF and the

clinical breakpoint

The ECOFF may beThe ECOFF may behigher, the same, lowerthan a clinical breakpoint

6

Brown - EUCAST definitions

Clinical breakpoint higher than ECOFF

ECOFF S breakpoint R breakpoint

Clinical breakpoint same as ECOFF

S/I and R breakpoint

ECOFF

Clinical breakpoint lower than ECOFF

ECOFF

S breakpoint R breakpoint

7

Brown - EUCAST definitions

ECOFF and zone diameters

Wild type

ECOFF

EUCAST breakpoint tables v 1.3

EUCAST breakpoint table notes

Highlight indicates change since last version

8

Brown - EUCAST definitions

S ≤ , R >MIC R>4 mg/L ≡ ≥8 mg/LZone R<24mm ≡ ≤ 23 mm

EUCAST breakpoint format

S ≤1 R >4S ≤1, R >4

Susceptible ResistantI

S ≤1, R ≥8

Susceptible ResistantI

12864321684210.5

EUCAST intermediate category

Intermediate category is not displayede.g. Ciprofloxacin S≤0.5 mg/L, R>1 mg/L,Intermediate inferred >0.5-1 mg/L

S ≥ 22 mm mg/L, R<18 mm,Intermediate inferred 18-21 mm

“-” Susceptibility testing not recommended as the species is a poor target for therapy with the drug(do not test, or

EUCAST table abbreviations

do not report, orreport as R without testing)

“IE” Insufficient evidence to set a breakpoint (report MIC values with comment but no categorical interpretation)

9

Brown - EUCAST definitions

“NA” Not Applicable (mostly used for screening tests when they are not applicable to particular organisms)

EUCAST table abbreviations

“IP” In preparation (breakpoints will be established)

Click on antibiotic for Rationale Document

EUCAST breakpoint table links to rationale documents

Click on MIC breakpoint for MIC distribution

EUCAST breakpoint table links to MIC distributions

10

Brown - EUCAST definitions

Click on zone breakpoint for zone diameter distribution

EUCAST breakpoint table links to zone diameter distributions

EUCAST website (www.EUCAST.org)

EUCAST MIC and zone diameter distributions website

11

Brown - EUCAST definitions

EUCAST MIC and zone distributionsSelect MIC or zone diameter distribution

Select agent or species

Blue indicates wild type

Clinical breakpoints and ECOFF

Link to graph

EUCAST MIC distributions

Do not infer resistance rates

May include truncated distributions

EUCAST MIC distributionsInsufficient data to define ECOFF

12

Brown - EUCAST definitions

EUCAST zone diameter distributions

EUCAST MIC zone diameter correlation

Summary

• EUCAST provides clinical breakpoints, non-species related breakpoints and epidemiological cut-off values (ECOFF)

• Be aware of formatting conventions and• Be aware of formatting conventions and abbreviations in EUCAST tables and on EUCAST MIC and zone distributions website

www.EUCAST.org

13

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

An MIC is an MIC is an MIC, isn’t it?

Gunnar KahlmeterGunnar KahlmeterClinical microbiology

Växjö, Sweden

MICMIC

MICMICMICMICMICMICMIC

MIC• MIC – the minimum inhibitory concentration

(mg/L or µg/mL)

• The lowest concentration in a series of twofold concentrations that will inhibit the growth of a microorganism, as measured by the naked eye.

• Convention: The series of concentrations shall contain the concentration 1 mg/L.

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Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

MICin vitroin vitro

relative

If you perform MIC determinations on many isolates of a well defined species using a standardized method, this is what you get:

3615 MICs from 11 data sources

…or this:

87 764 MICs from 33 data sources

15

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

…or this29 049 MICs from 13 data sources

….a distribution of MICs covering 3 – 5 dilution steps in a series of two-fold

dilutions.

Methods for MIC determination

• Broth dilution• Broth microdilution* • Agar dilution• Gradient tests

*ISO standard for non-fastidious microorganisms

Broth dilution Gradient MIC test

Several manufacturers:bioMerieux

OxoidLiofilchem

Broth microdilution Agar dilution MIC testing

16

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

Features of MIC dilution methodsBroth MIC

Agar MIC

Gradient test

Disk diffusion

Contamination detected

No Yes Yes Yes

Inoculum effect- suphonamides- beta-lactamase

+++ + + +++

Useful for slow-growing (>24 h) organisms

+++ +++ ++ -

Direct AST possible (clin material)

No ? Yes Yes

Automation Yes Partial No (Partial)

Methods used in automated systems

• Broth microdilution– Limited dilution series

• no easy extension to embrace changes in breakpoints• Many results reported as ≤ X mg/L or > Y mg/L

– Two concentrations only – S and R breakpointTwo concentrations only S and R breakpoint• ”black box” results

– Growth characteristics in the presence and absence of antibiotics at varying but few concentrations

• Not true MIC-values• no easy extension to embrace changes in breakpoints• many results reported as ≤ X mg/L or > Y mg/L

• Gradient tests – semiautomated ??• Disk diffusion – semiautomated ??

ISO 20776-1 (2006)• Title: “Clinical laboratory testing and in vitro diagnostic test

systems - Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices” Part 1: “Reference method for testing the in vitro activity of antimicrobial agents against rapidly growing aerobic g g p y g gbacteria involved in infectious diseases”.

• Broth microdilution technique.• Rapidly growing aerobic bacteria involved in infectious

diseases.• 2.5-5% lysed horse blood for Streptococcus spp.• No recommendations for Haemophilus, anaerobes or other

fastidious organisms.

17

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

E.coli vs. several antibiotics

Broth microdilution

International standard for evaluating other susceptibility testing methods

• ISO 20776-2 (2007)Title: Clinical laboratory testing and in vitro diagnostic test systems - Susceptibility testing of infectious agents and evaluation of performance of antimicrobial susceptibility test devices.Part 2: Evaluation of performance of antimicrobial susceptibility test devices

• For comparison of other MIC methods, automated systems and disk diffusion with the ISO broth microdilution method

Is there a true (reproducible, useful) difference between individuals in the

wild type MIC distribution?

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Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

The width of the MIC (or zone diameter) distribution:

V i ti i f t th t i fl th ti it f th d

The median of the MIC (or zone diameter) distribution:

• The inherent susceptibility of the species to the drug• Anything systematically influencing the activity of the drug on the bug

– method, pH, cations, incubation atmosphere

• Variations in exogenous factors that influence the activity of the drug (pH, cations, incubation atmosphere and time, etc)

• Variations in endogenous factors among individual organisms that influence the activity of the drug – any biological characteristic such as generation time, nutrient

dependency, atmosphere dependency etc• The degree of standardisation of method used• The number of investigators & observations• The stability of the molecule• …

E. coli wild type; generation times (min) (n=100) Expected Normal

20

25

30

35

f ob

s.

An example of biological variation not primarily related to antibiotic susceptibility.

5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

min

0

5

10

15

No.

of

The EUCAST MIC distributions show ”% organisms” and bars

when ”number of measurements are ≥1% of total”.

Very similar S. aureus vancomycin MIC

distributions from 33 sources using various

MIC methods

19

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

40000

50000

60000

70000

The EUCAST MIC data if presented as ” numbers” (not per cent) and with bars for all data.

Vancomycin / Staphylococcus aureus (n=87 764)EUCAST MIC distribution – Reference database 2011-04-21

0

10000

20000

30000

0 0 0.01 0.02 0.03 0.06 0.13 0.25 0.5 1 2 4 8 16 32 64 128 256 512

MICs performed with different methods are often surprisingly similar!

methods are often tightl calibrated against each other

Calibration

- methods are often tightly calibrated against each other- the degree of calibration at low end (wild type organisms) and high end (organisms with resistance mechanisms) may

differ and resistance mechanisms may affect different methods to varying extent.

20

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

Standardisation• If you provide the world at large with a not

too complicated recipee and all the ingredients, it is not surprising that Caesar salad is Ceasar salad is Caesar salad

…or an MIC is an MIC is an MIC…

”…albeit with a twist!””…and not necessarily the only salad!”

MIC reproducibility

A well standardised method can provide MICs at

/ 1 dil ti t 95% f ti+/- 1 dilution step 95% of time+/- 2 dilution step 99 % of time

(”rule of thumb”)

Spread of S. maltophilia ciprofloxacin MIC

distributions from 15 sources using various

MIC methodsMIC methods

21

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

Cefuroxime vs. E.coli

0.002 0.004 0.008 0.016 0.032 0.064 0.125 0.25 0.5 1 2 4 8 16 32 64 128 256 512Ciprofloxacin 0 0 0 0 0 0 1 4 28 52 16 0 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 0 55 1191 671 101 21 2 0 2 3 0 0Ciprofloxacin 0 0 0 0 0 0 0 4 45 363 454 119 11 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 2 2 15 32 2 0 1 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 3 80 256 61 11 1 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 5 64 155 17 4 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 4 35 130 51 3 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 197 251 41 10 1 0 1 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 16 125 102 28 3 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 8 96 209 59 1 2 0 0 1 0 0 0Ciprofloxacin 0 0 0 0 0 0 3 20 92 69 10 3 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 2 5 161 544 64 10 0 2 1 0 0 0 0Ciprofloxacin 0 0 0 0 6 4 4 13 245 854 379 9 6 1 1 1 0 0 0Ciprofloxacin 0 0 0 0 3 0 2 22 225 917 401 16 3 2 4 1 0 0 0Ciprofloxacin 0 0 0 0 0 1 3 9 426 933 138 11 5 2 1 0 2 0 0Ciprofloxacin 0 0 0 0 2 0 3 13 402 1193 222 19 10 0 6 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 2 75 366 182 30 4 0 0 2 0 0 0

S.pneumoniae vs ciprofloxacin

Ciprofloxacin 0 0 0 0 0 0 0 2 36 409 186 29 2 1 1 1 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 2 207 1052 225 22 2 10 0 1 0 0 0Ciprofloxacin 0 0 0 0 6 7 25 130 2195 10500 4618 144 67 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 8 10 47 176 95 21 1 2 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 2 302 1777 786 102 1 6 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 2 103 335 58 11 0 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 7 100 265 26 5 0 1 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 1 1 4 35 130 51 3 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 8 37 60 16 1 0 0 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 3 20 228 280 49 11 1 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 15 122 99 28 3 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 10 120 331 78 2 2 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 2 3 27 155 111 18 4 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 0 50 544 149 23 2 0 1 2 1 0 0Ciprofloxacin 0 0 0 0 0 4 4 10 181 256 74 6 2 0 1 0 0 0 0Ciprofloxacin 0 0 8 13 9 8 4 34 77 210 76 9 18 1 0 0 0 3 0Ciprofloxacin 0 0 0 0 0 1 0 14 120 272 96 8 0 2 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 66 85 31 2 1 4 0 0 0 0 0 228Ciprofloxacin 0 0 0 0 0 0 0 0 1 65 150 18 4 0 1 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 1 2 41 99 55 11 1 0 0 0 0 0 0Ciprofloxacin 0 0 0 0 0 0 0 422 2706 13072 3987 320 68 31 82 62 0 0 0

22

Kahlmeter - A MIC is a MIC is a MIC – isn’t it?

Variables that may affect MICs in broth dilution tests

• Medium (type, brand, batch)– all antibiotics and microorganisms

• Incubation time– ..the longer the higher the MIC…

• Incubation temperature– affects growth, antibiotic activity, expression of resistance mechanism, diffusion

• Inoculum – size– The larger the inoculum, the higher the MIC

• Inoculum – growth phase – the condition of the organisms affects the lag phase – the longer the lag phase, the

lower the MIC• Atmosphere

– examples: CO2 affects pH which affects macrolides; anaerobic atmosphere results in lower metronidazole MICs for Helicobacter pylori

• pH– Some antibiotics are more active in alkaline and some in acid environment: examples

to follow. • Ion content

– Aminoglycosides are affected by Ca++, Mg++ and daptomycin by Ca++

• Reading problems– Trailing endpoints (Acinetobacter vs. betalactams)

MIC – in summaryPros• Basis for all phenotypic susceptibility testing of bacteria

and fungi• Quantifiable• Predicts susceptibility and resistance• Can be highly standardized for most antibiotics and• Can be highly standardized for most antibiotics and

species

Cons• In vitro• Relative• Requires tight standardisation

23

Johan Mouton - PK-PD tools for breakpoints definition

PK/PD Tools for setting breakpoints

JWM Milan 07-05-11

Johan W. Mouton MD PhD FIDSA

LAB REPORT

MIC testing

JWM Milan 07-05-11

MIC testing

Susceptibility Report

• Provides Clinician/Consultant guidelines how to optimally treat a

ti t (F l

JWM Milan 07-05-11

patient (Freely translated from EUCAST guideline)

24

Johan Mouton - PK-PD tools for breakpoints definition

Lowest concentration with no visible growth

MIC

MICMeasure of Potency

JWM Milan 07-05-11

with no visible growthafter 18 hour incubation

.25 .5 1 2 4 8

MIC = 2 mg/L

Efficacy of the drug

JWM Milan 07-05-11

Potency of a drug(MIC)

Exposure to the bugIn vivo(PK)

Potency of a drugin vitro (MIC)

Exposure to the bugin vivo (PK)

Antimicrobial Efficacy of the Drug (Microbiological Cure)

Dosing Regimen

JWM Milan 07-05-11

(Microbiological Cure)

Effect on Host ( Clinical Cure)

Mouton et al., Drug Resistance Updates 2011

25

Johan Mouton - PK-PD tools for breakpoints definition

AUC is usuallylinearly related to Dose

Pharmacokinetic parameters :Measures of Exposure

JWM Milan 07-05-11

AUC

Pharmacokinetic Parameter (and Dose) MIC

JWM Milan 07-05-11

• Thus, we have to:– Establish a relationship between the MIC in vitro

and concentrations in vivo (thus, dosing regimens)– Determine MICS that can be covered by the

dosing regimen used– Determine the highest MIC that can be covered for

all patients, given the dose

JWM Milan 07-05-11

Susceptible (S)

A micro-organism is defined as susceptible by a level of antmicrobial activity associated with ahigh likelihood of therapeutic success. A micro-organism is categorized as susceptible by applying the appropriate breakpoint in a defined phenotypic test system.

Note: This breakpoint may be altered with legitimate changes in circumstances

Intermediate (I)A micro-organism is defined as intermediate by a level of antimicrobial activity associated with indetermiate therapeutic effect. A micro-organism is categorized as intermediate by applying the appropriate breakpoints in a defined phenotypic test system.Note: This breakpoints may be altered with legitimate changes in circumstances.Resistant (R)bacteria are defined as resistant by a level of antimicrobial activity associated with a high likelihood of therapeutic failure. A micro-organism is categorized as resistant by applying the appropriate breakpoint in a defined phenotypic test system.Note: This breakpoint may be altered with legitimate changes in circumstances

WWW.EUCAST.ORG

26

Johan Mouton - PK-PD tools for breakpoints definition

Any idea where we are today?

No idea

JWM Milan 07-05-11

No idea… may be a mouse?

Might be a human, though…

An elephant….Today it is an elephant!

JWM Milan 07-05-11

THE TARGET IS THE MICRO-ORGANISM

JWM Milan 07-05-11

27

Johan Mouton - PK-PD tools for breakpoints definition

Neutropenic Mouse Thigh-Infection Model

2. Bacteria injected into thighs on day 0 (106-7)

1. Neutropenia induced by 2injections of cyclophosphamideon days -4 and -1

JWM Milan 07-05-11

3. Treatment (usually given SQ)started 2 hr after infection and continued for 1-5 days

4. Thighs removed, homogenized, serially diluted and plated forCFU determinations

Modified from Craig, ISAP

Fluconazole efficacy in miceDose vs MIC

JWM Milan 07-05-11Andes et al ISHAM 2003

Pharmacokinetic parameter MIC

'Normalizing pk/pd relationships'

JWM Milan 07-05-11

Pharmacodynamic index (AUC/MIC, Peak/MIC, T>MIC)

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Johan Mouton - PK-PD tools for breakpoints definition

Fluconazole Pharmacodynamics Against Isogenic Strain Pairs ofSusceptible and Resistant C. albicans

0 C

FU/K

idne

ys

-1.0

-0.5

0.0

1649 MIC 0.252183 MIC 4.0 - CDR1002 MIC 1.02823 MIC 32 - MDR1, ERG 112-76 MIC 1 0

R2 = 84%

JWM Milan 07-05-11

24-h Total Dose0.1 1 10 100 1000

Cha

nge

in L

og1 0

-3.5

-3.0

-2.5

-2.0

-1.5 2-76 MIC 1.012-99 MIC 64 - CDR, MDR1, ERG 11412 MIC 0.252307 MIC 128 - CDR, ERG 11580 MIC 0.502438 MIC 32FH1 MIC 1.0FH5 MIC 4.0 - CDR

0.01 0.1 1 10 100 100010000

24-hr AUC/MIC

Andes et al ISHAM 2003

0.6

0.8

1.0

EC50 43.69

R² 0.9938

cure

Probability of cure after treatment with fluconazoleOropharygeal Candidiasis n=132

•Prob cure correlates with AUC/MIC

•POSITIVE correlation with

JWM Milan 07-05-11

0 1 2 30.0

0.2

0.4

log AUC/MIC

prob

Rodriguez- Tudela et al, AAC 2007

•POSITIVE correlation with EXPOSURE

•INVERSE correlation with MIC

Pharmacodynamic index (AUC/MIC)

Relationships Between 24-Hr fAUC/MIC and Efficacy against Pneumococci for Fluoroquinolones in Animals

ity (%

)

60

80

100

• A clear relationship exists between exposure and effect

• ff

JWM Milan 07-05-11

24-Hr AUC/MIC1 2.5 10 25 100 250 1000

Mor

tali

0

20

40

Andes & Craig, Int J of Antimicrob Agents 19:259, 2002

• A maximum effect is reached at ratio's of 25-35 (mortality)

29

Johan Mouton - PK-PD tools for breakpoints definition

Relationship between fAUC/MIC and Effect121 patients with S. pneumoniae respiratory infection

fAUC/MIC cut-off ~34

• Relationship between fAUC:MIC ratio & microbiological response from a total 121 patients with

i t t t i f ti

JWM Milan 07-05-11Ambrose PG, Bhavnani SM, Owens RC. Infect Dis Clin N Amer. 2003;17:529-543.

respiratory tract infection involving S. pneumoniae.

• fAUC:MIC > 34 had 92.6% response rate.

• fAUC:MIC < 34 had 66.7% response rate.

AUC/MIC mouse

AUC/MIC human

Quantitative relationship : exposure in mice and men

JWM Milan 07-05-11

24-Hr AUC/MIC1 2.5 10 25 100 250 1000

Mor

talit

y (%

)

0

20

40

60

80

100

~ 30-35

Correlation

Efficacy of an antimicrobial

Animal Human

Correlation

JWM Milan 07-05-11

CorrelationTreatment - Effect

CorrelationTreatment - Effect

Outcome parameter Outcome parameter

Qualitative relationship (pk/pd index)

Quantitative relationship (value pk/pd index)

30

Johan Mouton - PK-PD tools for breakpoints definition

Here, we observe that the pk/pd

Index (NOT dose!!!) matches

lit ti l

JWM Milan 07-05-11

-qualitatively

-quantitatively

Relationship between fAUC/MIC and Effect121 patients with S. pneumoniae respiratory infection

fAUC/MIC cut-off ~34

• Relationship between fAUC:MIC ratio & microbiological response from a total 121 patients with

i t t t i f ti

JWM Milan 07-05-11Ambrose PG, Bhavnani SM, Owens RC. Infect Dis Clin N Amer. 2003;17:529-543.

respiratory tract infection involving S. pneumoniae.

• fAUC:MIC > 34 had 92.6% response rate.

• fAUC:MIC < 34 had 66.7% response rate.

Clearly, there is a direct relationship between pk/pd index (AUC/MIC) and effect

higher values are associated with a higher likelihood of therapeutic success

JWM Milan 07-05-11

PK/PD Index

ther

apeu

tic s

ucce

ss

31

Johan Mouton - PK-PD tools for breakpoints definition

0.6

0.8

1.0

EC50 43.69

R² 0.9938

cure

Probability of cure after treatment with fluconazoleOropharygeal Candidiasis n=132

•Prob cure correlates with AUC/MIC

•POSITIVE correlation with

JWM Milan 07-05-11

0 1 2 30.0

0.2

0.4

log AUC/MIC

prob

Rodriguez- Tudela et al, AAC 2007

•POSITIVE correlation with EXPOSURE

•INVERSE correlation with MIC

Pharmacodynamic index (AUC/MIC)

It is not only for Mice

JWM Milan 07-05-11Ambrose et al, CID 2007

SETTING A BREAKPOINT –PK/PD

DETERMINE THE PK/PD TARGET e.g. value of the PK/PD Index

JWM Milan 07-05-11

ESTIMATE EXPOSURE from the dosing regimen and PK

CALCULATE BREAKPOINT from PK/PD target = PK/PD Index

32

Johan Mouton - PK-PD tools for breakpoints definition

Be sure that the fAUC/MIC ratio is at least appr. 34 in every patient

GOOD Clinical Practice

JWM Milan 07-05-11

p

AUC

MIC

6

8

10

onc

mg/

l

Levofloxacin 500 mg

fAUC = 30-50 mg/L

JWM Milan 07-05-11

0 4 8 12 16 20 240

2

4

time h

co

Clinical practice :

When starting treatment, we do not know :

JWM Milan 07-05-11

• the AUC in the individual patient

0 4 8 12 16 20 240

2

4

6

8

10

time h

conc

mg/

l

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Johan Mouton - PK-PD tools for breakpoints definition

Pharmacokinetics

Some people are more

JWM Milan 07-05-11

equal than others…

0.2

0.3

rel f

req

fAUC distribution levofloxacin (monte carlo simulation)

JWM Milan 07-05-11

24.00

0

28.00

0

32.00

0

36.00

0

40.00

0

44.00

0

48.00

0

52.00

0

56.00

0

60.00

0

64.00

0

68.00

0

72.00

00.0

0.1

fAUC

0.2

0.3

rel f

req

fAUC distribution levofloxacin (monte carlo simulation)

JWM Milan 07-05-11

24.00

0

28.00

0

32.00

0

36.00

0

40.00

0

44.00

0

48.00

0

52.00

0

56.00

0

60.00

0

64.00

0

68.00

0

72.00

00.0

0.1

fAUC

34

Johan Mouton - PK-PD tools for breakpoints definition

JWM Milan 07-05-11

On the average, this duck is dead

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

35

Johan Mouton - PK-PD tools for breakpoints definition

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

36

Johan Mouton - PK-PD tools for breakpoints definition

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

AUC

/MIC

The fAUC is calculated for 10.000 patients using MCSThis results in a probability distribution of AUCs

The fAUC/MIC is calculated for each MIC

10.000 pt

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

Mouton et al., 2004

80100120140160180200

99% percentile

levofloxacin 500 mg x 1 oral

95% percentile

fAUC

/MIC

JWM Milan 07-05-11

0.25 0.5 1 2 4 80

20406080

mean

MIC mg/L

fA

S = 1 mg/L

EUCAST., 2004

37

Johan Mouton - PK-PD tools for breakpoints definition

JWM Milan 07-05-11

High dose levofloxacin2x 500 mg, or 750 mg

AUC 70-80

JWM Milan 07-05-11

35 = 70 /2target

20406080

100120140160180200

99% CI

Average

ciprofloxacin 500 mg q12h oral

fAU

C/M

IC

JWM Milan 07-05-11

S = 0.5 mg/LPk/Pd

0.25 0.5 1 2 4 80

20

MIC mg/L

“He chose poorly”

-Knight from Indiana Jones: The Last Crusade

38

Johan Mouton - PK-PD tools for breakpoints definition

Be sure that the fAUC/MIC ratio is at least appr. 34 in every patient

GOOD Clinical Practice

JWM Milan 07-05-11

p

This includes patients with a high clearance

Bugs with MICs that can be expected

SETTING A BREAKPOINT –PK/PD

DETERMINE THE PK/PD TARGET e.g. value of the PK/PD Index

JWM Milan 07-05-11

ESTIMATE EXPOSURE from the dosing regimen and PK, includingpopulation variability

CALCULATE PK/PD BREAKPOINT from PK/PD target = PK/PD Index

JWM Milan 07-05-11

Susceptible (S)

A micro-organism is defined as susceptible by a level of antmicrobial activity associated with ahigh likelihood of therapeutic success. A micro-organism is categorized as susceptible by applying the appropriate breakpoint in a defined phenotypic test system.

Note: This breakpoint may be altered with legitimate changes in circumstances

Intermediate (I)A micro-organism is defined as intermediate by a level of antimicrobial activity associated with indetermiate therapeutic effect. A micro-organism is categorized as intermediate by applying the appropriate breakpoints in a defined phenotypic test system.Note: This breakpoints may be altered with legitimate changes in circumstances.Resistant (R)bacteria are defined as resistant by a level of antimicrobial activity associated with a high likelihood of therapeutic failure. A micro-organism is categorized as resistant by applying the appropriate breakpoint in a defined phenotypic test system.Note: This breakpoint may be altered with legitimate changes in circumstances

WWW.EUCAST.ORG

39

Brown - Rationale for new or revised EUCAST clinical breakpoints

Rationale for new or revisedRationale for new or revised EUCAST clinical breakpoints

Derek Brown

ECCMID 2011, Milan

Setting breakpoints in EUCAST

• Harmonization of European breakpoints

• Setting breakpoints for new agents (with EMA)EMA)

• Review of established breakpoints

EUCAST procedure for harmonizing breakpoints

• Collect and evaluate data in Steering Committee

• Consult on proposed breakpoints• Decision and publication with rationale

Breakpoints for all more widely used agents have been reviewed and harmonized breakpoints agreedSome less common agents and organisms currently under review

40

Brown - Rationale for new or revised EUCAST clinical breakpoints

Setting breakpoints for new agents• Pharmaceutical company submits new agent to European

Medicines Agency (EMA) for marketing approval • Relevant data are shared with the EUCAST Steering

Committee (confidential process)• EMA approves (or not) clinical indications, dosages,

administration forms and target organisms• In consultation with national breakpoint committees• In consultation with national breakpoint committees

EUCAST sets breakpoints for organisms approved by EMA

• Breakpoints set for daptomycin, tigecycline, doripenem and retapamulin (epidemiological cut-off value)

• Currently two agents in process • Ceftobiprole, garenoxacin, iclaprim, oritavancin withdrawn

Review of breakpoints by EUCAST• New resistance mechanisms• New agent in class• New clinical data• Extended indications

Ch i d i d i i t ti• Change in dosing or administration• Change in target organisms

Breakpoints reviewedGlycopeptides, carbapenems, colistin, cephalosporins, monobactams

41

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST rationale documents

EUCAST rationale documentsDosages in different countries

EUCAST rationale documentsMIC distributions and ECOFFs

42

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST rationale documentsBreakpoints prior to harmonization

EUCAST rationale documentsPharmacokinetics

EUCAST rationale documentsPharmacodynamics

43

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST rationale documentsMonte Carlo simulations and

Pk/Pd breakpoints

EUCAST rationale documentsClinical data

EUCAST rationale documentsClinical breakpoint summary

Non-species-related breakpoints

S i l t d b k i tSpecies-related breakpointsExplains deviations from non-species-related BPs

Species without breakpoints, with explanation

Clinical qualifications, e.g. UTI only

Dosage

Additional comments

44

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST doripenem breakpoints

doripenem 500 mg x 3 iv

Pk/Pd and MC analysis indicated non-species-related breakpoints of S≤1, R>4 mg/L

Non-species-relatedbreakpoints

0.125 0.25 0.5 1 2 4 8 16 320

20

40

60

80

100

99% percentile

Mean

95% percentile

MIC mg/L

fT>M

IC

EUCAST doripenem breakpoints

S≤ R>Enterobacteriaceae 1 4Pseudomonas 1 4Acinetobacter 1 4

Species-relatedbreakpoints

Acinetobacter 1 4

Streptococci 1 1H. influenzae 1 1M. catarrhalis 1 1Anaerobes 1 1

EUCAST doripenem breakpointsStaphylococcus spp. Susceptibility inferred from methicillin susceptibility

Enterococcus spp. a poor targetSpecies withoutbreakpoints

N. gonorrhoeae Insufficient evidence

breakpoints

45

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST carbapenem breakpoints

• Other carbapenem breakpoints (imipenem, meropenem, ertapenem) reviewed at same time

• Considered no strong evidence supporting a change from established breakpoints

Revision of EUCAST glycopeptide breakpoints

Original vancomycin breakpoints for S. aureus (S ≤4 mg/L, R >8 mg/L) did not distinguish VISA from susceptiblenot distinguish VISA from susceptible isolates.

Old EUCAST vancomycin breakpoints for Staphylococcus spp.

VISA VanA

IS R

46

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST vancomycin breakpoints

Insufficient data to set non-species-related breakpoints

Non-species-relatedbreakpoints

EUCAST vancomycin breakpoints

S≤ R>Staphylococcus spp. 2 2Enterococcus spp. 4 4

Species-relatedbreakpoints

Streptococci 2 2Anaerobes (Gm +ve) 2 2

“GISA/VISA” isolates reported resistant - serious infections with “GISA/VISA” isolates are not treatable with increased doses of vancomycin.VanA reported resistant

New EUCAST vancomycin breakpoints for Staphylococcus spp.

VISA VanA

IS R

S R

47

Brown - Rationale for new or revised EUCAST clinical breakpoints

EUCAST vancomycin breakpoints

S≤ R>Staphylococcus spp. 2 2Enterococcus spp. 4 4

Species-relatedbreakpoints

Streptococci 2 2Anaerobes (Gm +ve) 2 2

Avoids dividing the wild type MIC distribution and isolates with vanA or vanB will be reported resistant.

New vancomycin breakpoints for Enterococcus spp.

IS R

S R

EUCAST vancomycin breakpoints

S≤ R>Staphylococcus spp. 2 2Enterococcus spp. 4 4

Species-relatedbreakpoints

Streptococci 2 2Anaerobes (Gm+ve) 2 2

Strains with MIC values above 2 mg/L are rare or not yet reported.

48

Brown - Rationale for new or revised EUCAST clinical breakpoints

New vancomycin breakpoints for Streptococcus spp.

S R

S R

EUCAST vancomycin breakpoints

Species withoutbreakpoints

Enterobacteriaceae, Pseudomonas spp., Acinetobacter spp., Haemophilusinfluenzae Moraxella catarrhalisp influenzae, Moraxella catarrhalis, Neisseria spp. and Gram-negative anaerobes all poor targets (Gm –ve)

EUCAST strategy for topical antimicrobial agents

• Local concentrations may be high but there are rarely any data correlating MICs to clinical outcome

• There is often anecdotal evidence that an agent is effective in specific conditions in which case itis effective in specific conditions in which case it can at least be assumed that wild type isolates are susceptible

• If there is already a clinical breakpoint for the agent, this can be applied for topical preparations also

• Otherwise the ECOFF can serve in lieu of a clinical breakpoint

49

Brown - Rationale for new or revised EUCAST clinical breakpoints

Topical agents - Retapamulin

• New agent for impetigo and superficial skin infections

• ECOFF set by EUCAST as part of the marketing authorisation by EMA

ECOFF 0.25 mg/L

ECOFF 0.125 mg/L

50

Brown - Rationale for new or revised EUCAST clinical breakpoints

Topical agents - Mupirocin

• Mainly used for nasal decolonization of Staphylococcus aureus, particularly MRSA, as part of decolonization regimens.

• May also be used for topical treatment of uncomplicated skin infections such as impetigo, although prolonged use is associated with selection of resistance.

• EUCAST breakpoints are related specifically to nasal decolonization of S. aureus.

Wild type

ChromosomalmupA

PlasmidmupA

ECOFF 1 mg/L

Mupirocin clinical studies• Topical mupirocin is effective in nasal

decolonization of wild type S. aureus (MIC ≤1 mg/L)

• Low-level resistant isolates (MIC 8-256 mg/L) are initially cleared as effectively as wild type isolates but recolonization is very commonbut recolonization is very common

• Clearance rates for high-level resistant isolates (MIC >256 mg/L) are low

• There is no evidence on outcome for isolates with MICs above the wild type but without a recognised resistance mechanism (MIC ≤4 mg/L)

51

Brown - Rationale for new or revised EUCAST clinical breakpoints

S RI

ChromosomalmupA

PlasmidmupA

S RI

Other topical agents

• Systemic breakpoints availableChloramphenicol TetracyclineGentamicin Fusidic acidPolymyxin B Ofloxacin

• ECOFFs to be definedNeomycin (Framycetin) Bacitracin

EUCAST breakpoints under development for less

commonly tested organisms• Clostridium difficile• Helicobacter pylori• Helicobacter pylori• Listeria monocytogenes• Pasteurella multocida• Campylobacter jejuni/coli• Corynebacterium spp• Burkholderia cepacia

52

Brown - Rationale for new or revised EUCAST clinical breakpoints

Clostridium difficile ”breakpoints”

• Set in consultation with the ESCMID C. difficilestudy group (ESGCD)

• There are no clinical or pharmacodynamic data. Breakpoints are therefore ECOFFsp

• Several agents are included for epidemiological purposes only. They are inappropriate for treatment. ECOFFs have been defined when sufficient MIC distributions are available

• Few MIC distributions are available for some agents, so some ECOFFs are tentative

Clostridium difficile – ECOFFs

Agent ECOFF (mg/L) Comment

Metronidazole ≤2Vancomycin ≤2yFusidic acid ≤2

Tested for epidemiological purposes only.

Moxifloxacin ≤4

Rifampicin ≤0.004

Tigecycline ≤0.25

Daptomycin ≤4

Helicobacter pylori breakpoints

• Different test methods may give different results

• There is a shortage of clinical data linking inThere is a shortage of clinical data linking in vitro susceptibility to outcome

• All agents are used in combination therapy so outcome data for individual agents are difficult to assess.

53

Brown - Rationale for new or revised EUCAST clinical breakpoints

Agent S (mg/L)

R (mg/L) Comment

Amoxicillin ≤0.12 >0.12Based on ECOFF. Isolates with higher MICs uncommon. No outcome evidence for MIC >0.12 mg/L.

Clarithromycin ≤0.25 >0.5Clinically validated. Isolates with MIC above 0.5 mg/L have 23S RNA mutation. ECOFF 0.25 mg/L.Largely correlate with gyrA mutations, no

Helicobacter pylori proposed breakpoints

Levofloxacin ≤1 >1Largely correlate with gyrA mutations, no outcome data. ECOFF 0.5 mg/L.

Tetracycline ≤1 >1Correspond with mutation in 16S RNA. Resistance rare and no clinical validation. ECOFF 0.25 mg/L.

Rifampicin ≤1 >1Correspond with rpoB mutation. Resistance rare and no clinical validation. Few MIC data.

Metronidazole ≤8 >8Current, widely accepted breakpoint, but no clinical validation. ECOFF 4 mg/L.

Subcommittee on antifungal susceptibility testing

(EUCAST-AFST)• Chair: J-L Rodriguez-Tudela (ES),

Scientific secretary: JP Donnelly (N)

• AFST Steering Committee members: MC Arendrup (DK), C Lassl-Flörl (A), W Hope (UK)

• National representatives: See EUCAST websitehttp://www.eucast.org/organization/subcommittees/eucast_afst

AFST published breakpoints

Agent Organisms S ≤ (mg/L)

R > (mg/L)

Fluconazole

Candida albicans 2 4Candida glabrata IE IECandida tropicalis 2 4Fluconazole Candida tropicalis 2 4Candida krusei - -Candida parapsilosis 2 4

Voriconazole

Candida albicans 0.125 0.125Candida glabrata IE IECandida tropicalis 0.125 0.125Candida krusei IE IECandida parapsilosis 0.125 0.125

54

Brown - Rationale for new or revised EUCAST clinical breakpoints

AFST proposed breakpointsAgent Organisms S ≤ (mg/L) R> (mg/L)

Amphotericin B

Candida albicans 1 1Candida glabrata 1 1Candida tropicalis 1 1Candida krusei 1 1Candida parapsilosis 1 1Candida other species IE IE

Candida albicans 0.06 0.06C did l b t IE IE

Posaconazole

Candida glabrata IE IECandida tropicalis 0.06 0.06Candida krusei IE IECandida parapsilosis 0.06 0.06Candida guilliermondii IE IE

Anidulafungin

Candida albicans 0.03 0.03Candida glabrata 0.06 0.06Candida tropicalis 0.06 0.06Candida krusei 0.06 0.06Candida parapsilosis - -Candida guilliermondii IE IE

SummaryRationale for EUCAST breakpoints

• EUCAST breakpoints set to harmonize old breakpoints, establish new breakpoints, revise breakpointsTh b k d d t d ti l f• The background data and rationale for breakpoints are described in EUCAST rationale documents

• The rationale document series will be extended as new breakpoints are set or revised as existing breakpoints are reviewed

55

Rafael Canton - What is new in EUCAST expert rules?

ANTIMICROBIAL SUCEPTIBILITY TESTINGANTIMICROBIAL SUCEPTIBILITY TESTING

WHAT IS NEW IN EUCAST EXPERT RULES? WHAT IS NEW IN EUCAST EXPERT RULES?

www.EUCAST.org

Departamento de Microbiología IIUniversidad Complutense. Madrid

Hospital Universitario Ramón y CajalSERVICIO DE MICROBIOLOGÍA Y PARASITOLOGÍA

Dr. Rafael Cantón

Antimicrobial susceptibility testing (AST)Antimicrobial susceptibility testing (AST)

MIC (mg/L)

and / or

inhibition zones (mm)

Clinical categorization (S, I, R)

Interpretive reading

Antimicrobial susceptibility testing (AST)Antimicrobial susceptibility testing (AST)

Based on clinical breakpoints

Application of expert rules

Based on resistance mechanisms knowledge

Based both on clinical evidence and resistance mechanisms knowledge

56

Rafael Canton - What is new in EUCAST expert rules?

1.- To establish the susceptibility phenotype

2.- To infer the potential resistance mechanism

InterpretiveInterpretive readingreading of of thethe antibiogramantibiogram

3.- To predict previously defined phenotype from theresistance mechanisms

Courvalin P, ASM News, 1992Livermore DM et al. J Antimicrob Chemother 2001; 48 (Suppl 1): 87-102

Cantón R. Enferm Infecc Microbiol Clin 2010; 28:375-385

Antibiogram interpretative reading

Importance of bacterial identification

Antimicrobial MIC (mg/L)

Ampicillin >64Amox/clav >32/16

Organisms Potential phenoype

E. coli AmpC hyperproductionplasmid AmpCAmox/clav >32/16

Ticarcillin >64Piperacillin 32Piper/Tazo 16/4Cefuroxime >64Cefoxitin >32Cefotaxime 4Ceftazidime 8Cefepime 1

plasmid AmpCESBL + porin deficiency

K. pneumoniae ESBL + porin deficiency

E. cloacae ESBL

Escherichia coli

Antibiogram interpretative reading: the classical example

Escherichia coliand ESBL

57

Rafael Canton - What is new in EUCAST expert rules?

AMP PIP CEF

CXM CAZ FOX

Proteus vulgarishiperproduction of chromosomal b-lactamase (Class A)

AmpicillinTicarcillinPiperacillinPiper/Tazo

>2568->2568->2568-32

MIC

RRS/RS/R

Interp.

CTX AMC FEP

ATM IPM

pAmox/clavCefalotinCefoxitinCefuroximeCefotaximeCeftazidimeCefepimeImipenem

4-8>2562-4>2562-80,12-0,50,5-20,5-2

S/IRSRRSS/IS

Clinical categorization (S, I, R)

Interpretive reading

Antimicrobial susceptibility testing (AST)Antimicrobial susceptibility testing (AST)

Based on clinical breakpoints

Application of expert rulesBased on resistance mechanisms knowledge

Based both on clinical evidence and resistance mechanisms knowledge

58

Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rulesEUCAST expert rules

An expert rule ...

Description of action to be taken, based on current clinicaland/or microbiological evidence, in response to specificantimicrobial susceptibility test results

Assist clinical microbiologists in the interpretation ofantimicrobial susceptibility tests results

Contribute to quality assurance by highlighting anomalousor unlikely results

www.eucast.org

EUCAST expert rules EUCAST expert rules v2v2

Version-2, approved in Vienna, Steering Committee, Feb-2011

Maintain version-1 structure but rules were revised according with:- new clinical and microbiological evidences

- new defined breakpoints (3rd gen. cephalosporins, ...)

- current breakpoints tables to avoid potential inconsistencies- withdrawal of expert rules of antibiotics for which breakpoints

have not been defined. If mention was needed, the ECOFFvalue was used, but not the clinical category (S or R)

Nomenclature of microorganisms has been updated

EUCAST expert rules EUCAST expert rules v2v2

All expert rules were - renumbered and reworded (when needed) - edited as: “IF ... THEN ... ”

Layout were modified:“agents tested” and “agents affected”- agents tested” and agents affected”

- “exceptions, scientific basis and comments” (same column)

Extensive list of performed modifications at the end of thedocument with a short explanation when needed

References were added or deleted according with previousmodifications

59

Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rules EUCAST expert rules v2v2

Expert rules: new layout

www.eucast.org

Agents tested Agents

affectedIF … THEN … Exceptions,

scientific basisand comments

EUCAST expert rulesEUCAST expert rules

The EUCAST expert rules in antimicrobial susceptibilitytesting are divided into:

- intrinsic resistances

- exceptional phenotypes

- interpretive rules

www.eucast.org

EUCAST expert rulesEUCAST expert rules

Intrinsic resistance

Opposed to acquired or mutational resistance

Characteristic of all (or almost all) representatives of the species

The antimicrobial activity of the drug is clinically insufficient orantimicrobial resistance innate as to render it clinically useless

Antimicrobial susceptibility testing is normally unnecessary

In these species, “susceptible” results should be viewed withcaution (this indicates an error in identification or susceptibility testing)

- if S is confirmed the drug should preferably not be used- R may be expressed at a low level (MIC close to the S breakpoint)

although the antibiotic is not considered clinically active

60

Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rules EUCAST expert rules v2v2

Intrinsic resistances affecting Enterobacteriaceae

www.eucast.org: version 2 modifications

EUCAST expert rules EUCAST expert rules v2v2

Intrinsic resistances affecting Enterobacteriaceae

P. rettgeri (but not P. stuartii) produces a chromosomal AAC(2’)-Ia enzyme and shouldbe considered resistant to allaminoglycosides except

www.eucast.org

amikacin and streptomycin.

Some isolates express theenzyme poorly and can appearsusceptible to netilmicin in vitro,but should be reported as resistant as mutation canresult in overproduction ofthis enzyme

EUCAST expert rules v2EUCAST expert rules v2

Intrinsic resistances affecting Enterobacteriaceae

www.eucast.org: version 2 modifications

61

Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rulesEUCAST expert rules

Exceptional phenotypes

Resistances of some bacterial species to particular antimicrobialagents which have not yet been reported or are very rare

They should be checked as they may also indicate an error inidentification or susceptibility testing If they are confirmed locally:identification or susceptibility testing. If they are confirmed locally:

- the isolate should be further studied - sent to a reference laboratory for independent confirmation

The may change with time as resistance may develop andincrease over time

There may also be local or national differences. Very rare in onehospital, area or country, may be more common in another

EUCAST expert rules EUCAST expert rules v2v2

Exceptional phenotypes: Gram-negatives

.

.

www.eucast.org

Ertapenem was removed from rule 5.1. … decrease susceptibility to thisdrug has been reported in isolates with both AmpC-hyperproduction andabsence or decreased expression of porins

: version 2 modifications

Evidences of expert rules

A. There is clinical evidence that reporting the test result assusceptible leads to clinical failures

EUCAST expert rulesEUCAST expert rules

B. Evidence is weak and based only on a few case reports oron experimental models. It is presumed that reporting the test result as susceptible may lead to clinical failures

C. There is no clinical evidence, but microbiological data suggest that clinical use of the agent should be discouraged

62

Rafael Canton - What is new in EUCAST expert rules?

Evidences

A. There is clinical evidence that reporting the test result assusceptible leads to clinical failures

EUCAST expert rules EUCAST expert rules v2v2

Evidences

B. Evidence is weak and based only on a few case reports oron experimental models. It is presumed that reporting the test result as susceptible may lead to clinical failures

EUCAST expert rules EUCAST expert rules v2v2

Evidences

C. There is no clinical evidence, but microbiological data suggest that clinical use of the agent should be discouraged

EUCAST expert rules v2EUCAST expert rules v2

63

Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rules EUCAST expert rules v2v2

Some major modifications

Old 9.1 and 9.8 expert rules has been deleted

- ESBL detection and clinical category modification in extended spectrum cephalosporins no longer exist (report as found)

- carbapenemase detection and clinical category modification incarbapenems no longer exist (report as found)

Haemophilus and β-lactams expert rules have been reworded

Old 13.7 expert rule (now 13.6)- nalidixic acid disk diffusion screen test for Salmonella and clinical

failure of fluoroquinolones due to acquisition of at least one targetmutation in gyrA has been substituted for ciprofloxacin MIC criteriaof >0.06 mg/L

33rdrd & 4& 4thth gen. cephalosporin breakpoints in gen. cephalosporin breakpoints in EnterobacteriaceaeEnterobacteriaceae

CefalosporinsCLSI (2010) EUCAST (2010)

S R S RCefotaxime ≤1 ≥4 ≤1 >2

Ceftriaxone ≤1 ≥4 ≤1 >2

Ceftazidime ≤4 ≥16 ≤1 >4

=

=

Ceftazidime ≤4 ≥16 ≤1 >4

Cefepime ≤8 ≥32 ≤1 >4

Aztreonam ≤4 ≥16 ≤1 >4

Remember! … R category is “≥” in CLSI while “>” in EUCAST

S/I‐breakpointsI/R‐breakpoints

2001

CLSI

4/18/2011 G Kahlmeter, EUCAST

CLSI

64

Rafael Canton - What is new in EUCAST expert rules?

S/I‐breakpointsI/R‐breakpoints2009

EUCAST CLSI

4/18/2011 G Kahlmeter, EUCAST

EUCAST CLSI

EUCAST expert rulesEUCAST expert rules

RuleNo.

Rule Exceptions Scientific basis Grade* References

9.1* If R or I to any 3rd or 4 th gen. oxyimino-ceph. (i.e. cefepime, cefotaxime, cefpirome, cefpodoxime, ceftazidime or ceftriaxone) or aztreonam, test for ESBL. If positive, edit the S result for any of these cephalosporins, including 4 th gen. agents and for

A few ESB producers may appear S in vitro to some 3rd

or 4 th gen. oxyimino-cephalosporin or aztreonam.Efficacy of cefotaxime,

C Burn-Buisson et al. 1987Jarlier V et al., 1988.Livermore DM and Brown DF, 2001.Wong-

Cephalosporins-ESBLs: Old 9.1 expert rule

p p g g gaztreonam, to I and edit the I result to R. ESBL producers may appear susceptible to penicillin/ ß-lactamase inhibitor combinations. The use of these combinations against ESBL producers remains controversial, and should be approached with caution. If ESBL negative see rule 9.2.

yceftazidime and ceftriaxoneagainst ESBL-producing isolates with MICs lower than 2 mg/L remains to be fully documented

WongBeringer A et al., 2002.Paterson D and BonomoR, 2005Paterson DL et al. 2004Bhavnani SM et al. 2006

* Enterobacteriaceae (for Klebsiella oxytoca and Citrobacter koseri see 9.3)A. There is clinical evidence that reporting the test result as susceptible leads to clinical failuresB. Evidence is weak based only on a few case reports or on experimental models. It is presumed that reporting the test as susceptible my lead to clinical failures C. There is currently no clinical evidence, but microbiological data suggest that clinical use of the agent should be discouraged

S/I‐breakpointsI/R‐breakpoints2010

EUCAST ESBL d t ti f SIR t i ti

CLSI: no ESBL‐detection for SIR‐categorisation

4/18/2011 G Kahlmeter, EUCAST

EUCAST:  no ESBL‐detection for SIR‐categorization

65

Rafael Canton - What is new in EUCAST expert rules?

2010

EUCAST expert rules EUCAST expert rules v2v2

CefalosporinsEUCAST

S (≤) R (>)

Cefotaxime 1 2

Ceftazidime 1 4

Cefepime 1 4

Ceftazidime and cefepimeR breakpoint were reducedfrom >8 mg/L to >4 mg/L

Report as found regardless of the presence of a resistance mechanism (ESBL or other)

AntibioticMIC

(mg/L)CLSI EUCAST

≤2009 2010 ≤2009 2010

Amoxicillin >16 R R R RAmox/clav 4/2a; 8/2b S S S SCefazolin >32 R R R R

E. coli with reduced susceptibility to 3rd & 4th gen. cephalosporins

Cephalosporin breakpoints in Enterobacteriaceae

Cefoxitin 4 S→R S NAc NAc

Ceftotaxime >16 R R R RCeftazidime 4 S→R S I→R ICefepime 2 S→R S I→R IAztreonam 4 S→R S I→R IImipenem 0.25 S S S SMeropenem 0.03 S S S SaCLSI: 2:1 ratio; bEUCAST: fixed concentration (2 mg/L); cNA: not available

40%50%60%70%80%90%100%

Escherichia coli (SMART* data base): 19.991 isolates

Cephalosporin breakpoints and Enterobacteriaceae

CTX‐CLSI CTX‐EUCAST CAZ‐CLSI CAZ‐EUCAST FEP‐CLSI FEP‐EUCAST

R 17,8 17,8 9,4 11 9,4 11

I 1 1 1,6 4,6 0,8 2,3

S 81,2 81,2 89 84,4 89,9 86,7

0%10%20%30%40%

*SMART: Study for Monitoring Antmicrobial Resistance Trends, 2002-2009

S ≤1 / R ≥4 S ≤1 / R >2 S ≤4 / R ≥16 S ≤1 / R >4 S ≤1 / R ≥4 S ≤1 / R >4

66

Rafael Canton - What is new in EUCAST expert rules?

BLEE - Escherichia coli – (SMART* data base): 2.893 isolates

40%50%60%70%80%90%100%

Cephalosporin breakpoints and Enterobacteriaceae

S ≤1 / R ≥4 S ≤1 / R >2 S ≤4 / R ≥16 S ≤1 / R >4 S ≤1 / R ≥4 S ≤1 / R >4

*SMART: Study for Monitoring Antmicrobial Resistance Trends, 2002-2009

CTX‐CLSI‐09

CTX‐CLSI‐10

CTX‐EUCAST

CAZ‐CLSI‐09

CAZ‐CLSI‐10

CAZ‐EUCAST

FEP‐CLSI‐09

FEP‐CLSI‐10

FEP‐EUCAST

R 100 91,8 91,8 100 43,3 58,5 100 61,6 66,4

I 4,6 4,6 15,2 19,6 4,8 12,9

S 3,6 3,6 41,5 21,9 33,6 20,7

0%10%20%30%40%

RuleNo.

Rule Exceptions Scientific basis Grade* References

9.7* If production of metallo- β -lactamases is confirmed, report the S as I and the I as R for any β-lactamexcept aztreonam which should be reported as found

Metallo-beta-lactamases can hydrolyse all β -lactams except

B Walsh et al., 2005

EUCAST expert rulesEUCAST expert rules

Carbapenems: Old 9.8 expert rule

except aztreonam, which should be reported as found lactams except monobactams

* Enterobacteriaceae, Acinetobacter spp., Pseudomonas spp.** Enterobacteriacaeae

A. There is clinical evidence that reporting the test result as susceptible leads to clinical failuresB. Evidence is weak based only on a few case reports or on experimental models. It is presumed that reporting the test as susceptible my lead to clinical failures C. There is currently no clinical evidence, but microbiological data suggest that clinical use of the agent should be discouraged

EnterobacteriaceaeFDA CLSI (2010)* EUCAST (EMEA) (2009)S S R S R ECOFF

Imipenem  ≤4 ≤1* ≥4* ≤2 >8 ≤0,5; ≤1**

Meropenem  ≤4 ≤1* ≥4* ≤2 >8 ≤0,125

Ertapenem ≤2 ≤0.25* ≥1* ≤0,5 >1 ≤0,06

Doripenem ≤0 5 ≤1* ≥4* ≤1 >4 ≤0 12

Carbapenem breakpoints and Enterobacteriaceae

Doripenem  ≤0,5 ≤1 ≥4 ≤1 >4 ≤0,12

*M100‐S20U June 2010 **E. coli y K. pneumoniae

Report as found regardless of the presence or absense of a carbapenemase

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Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rules EUCAST expert rules v2v2

Haemophilus influenzae and β-lactams

Rule 10.1 v2 (evidence grade A)

EUCAST expert rules EUCAST expert rules v2v2

Haemophilus influenzae and β-lactams

Rule 10.2 v2 (evidence grade C)

EUCAST expert rules EUCAST expert rules v2v2

Haemophilus influenzae and β-lactams

Rule 10.3 v2 (evidence grade C)

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Rafael Canton - What is new in EUCAST expert rules?

EUCAST expert rules v2EUCAST expert rules v2

Salmonella spp. and fluoroquinolones

Nalidixic ac. (zone diameter), previously recommended for detection offluoroquinolone resistance, had been removed in breakpoint tables

- it does not detect qnr-mediated resistance - low-level resistance in Enterobacteriaceae (exception Salmonella spp)

is no longer of major interest since high-level resistance is now common in species

Fluroquinolones breakpoints and Enterobacteriaceae

EUCAST expert rules v2EUCAST expert rules v2

Salmonella spp. and fluroquinolones

There is clinical evidence for ciprofloxacin to indicate a poor response insystemic infections caused by Salmonella spp. with low-level quinoloneresistance (MIC>0.064 mg/L). This mainly to S. typhi but there are alsocase reports of poor response with other Salmonella species

Future modification of fluoroquinolones breakpoints?

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Rafael Canton - What is new in EUCAST expert rules?

Salmonella Salmonella spp., nalidixic acid and fluoroquinolonesspp., nalidixic acid and fluoroquinolones

ECOFF ECOFF

S R EUCAST, 2011

ECOFF ECOFF

R S EUCAST, 2011RS EUCAST, 2011

Salmonella Salmonella spp., nalidixic acid and fluoroquinolonesspp., nalidixic acid and fluoroquinolones

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Rafael Canton - What is new in EUCAST expert rules?

MIC (mg/l)and / or

inhibition zones (mm)

Do your best... but better with EUCAST

ANTIMICROBIAL SUCEPTIBILITY TESTINGANTIMICROBIAL SUCEPTIBILITY TESTING

WHAT IS NEW IN EUCAST EXPERT RULES? WHAT IS NEW IN EUCAST EXPERT RULES?

www.EUCAST.org

Departamento de Microbiología IIUniversidad Complutense. Madrid

Hospital Universitario Ramón y CajalSERVICIO DE MICROBIOLOGÍA Y PARASITOLOGÍA

Dr. Rafael Cantón

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