evaluación del sistema de identificación y sensibilidad bd

Evaluación del sistema de identificación y

sensibilidad BD Phoenix de acuerdo al

standard EUCAST

EUCAST: Qué, por qué, cómo y cuándo: las claves del éxito

Malaga, 2 de junio, 2010

Departamento de Microbiología IIUniversidad Complutense. Madrid

Hospital Universitario Ramón y CajalSERVICIO DE MICROBIOLOGÍA Y PARASITOLOGÍA

Dr. Rafael Cantón

http://www.ucm.es/info/farmacia/Farma3.htm

1920 1930 1940 1950 1960 1970 1980 1990 2000

Discover of antimicrobial agents

Introduction ofantibiotic in therapeutics

Normalization of in vitro

susceptibility testing

Interpretivecriteria

Description ofresistance

mechanisms

Relation between resistance and clinical failure

Interpretive reading of the antibiograms

AutomationThe antimicrobial susceptibilitytesting process…

Cantón R. Enf Inf Microbiol Clin 2002; 20:176-85

MIC based automatic systems MIC based automatic systems

Main objectives

To produce antimicrobial susceptibility testing (AST) resultsin a mechanized mode

To standardize AST avoiding uncontrolled differences

To offer AST in a shorter period of time than manual methods

To interpret AST results (clinical categorization / interpretation)

Antimicrobial susceptibility automatic systemsAntimicrobial susceptibility automatic systems

Now with EUCAST breakpoints!


MIC based systems

Device Inoculation ReadingReporting time (hours)

Sensititre Manual orsemiautomatic

Manual read orfluorescence

18-24

MicroScan Manual Turbidity and fluorometer

15-183.5-7

Phoenix Manual orSemiautomatic

Turbidity andcolorimetric

4-16

Vitek2 Semiautomatic Fluorometer,photometer

4-18

Data obtained from Evangelista & Truant. In: Commercial methods in Clinical Microbiology. 2002

Issues with EUCAST breakpoint implementation

Lower ranges of concentrations

are needed (EUCAST breakpointsare mostly lower than CLSI)

-

instability of certain antibiotics might affect accuracy (essentialand categorical agreements)

-

carbapenems, β-lactam-β-lactamase inhibitor combinations, …

-

major discrepancies (false resistance) could be observed, particularlywith isolates expressing low level resistance mechanisms


Issues with EUCAST breakpoints implementation

S and R breakpoints can be ...

-

too close (essential and categorical agreements can be affected)

i.e. ciprofloxacin and enterobacteriaceae (S≤

0.5 / R >1)

vancomycin and staphylococci (S≤

2 / R >2)

-

too separate (a higher concentration range is needed in the panel)

i.e. aztreonam and P. aeruginosa (S≤

1 / R >16)*

*The R breakpoint was increased from 8 to 16 mg/L to avoid dividing thewild type MIC distribution. The R breakpoint relates to high dose therapy.The S breakpoint is set to ensure that wild type isolates are reported I.

Antimicrobial susceptibility and automatic systemsAntimicrobial susceptibility and automatic systems

www.eucast.org

Low level resistance or decreased susceptibility

High level resistanceRS

ECOFF

Issues with EUCAST breakpoint implementation

A desirable attribute...

... to include drug concentrations below or equal to ECOFFs*allowing detection of wild type organisms (no-R mechanism)

*epidemiological cut off values

A philosophical and technical change...

... breakpoints are differently expressed

S R

EUCAST ≤ >

CLSI ≤ ≥


www.eucast.org


MIC based systems

Device Inoculation ReadingReporting time (hours)

Sensititre Manual orsemiautomatic

Manual read orFluorescence

18-24

MicroScan Manual Turbidity and fluorometer

15-183.5-7

Phoenix Manual orSemiautomatic

Turbidity andcolorimetric

4-16

Vitek2 Semiautomatic Fluorometer,photometer

4-18

Data obtained from Evangelista & Truant. In: Commercial methods in Clinical Microbiology. 2002

These system fulfill FDA and ISO accuracy performance

Acceptable performance for the clinical data for automatic ASTdevices with reference method (FDA)

Essential agreement (±

1 dilution):

>89.9%

Category agreement (interpretive results, SIR) >89.9%

Major discrepancies (false resistance): ≤

3%* *based on the no. of susceptible organisms tested

Very major discrepancies (false susceptibility): ≤

1.5%****based on the no. of resistant organisms tested

Growth failure rates: < 10%***

***for any genus or species tested


Antimicrobial Susceptibility Test (AST) Systems. Guidance for Industry and FDA Class II Special Controls Guidance Document:, August 28, 2009

http://www.fda.gov/MedicalDevices/DeviceRegulationandGuidance/GuidanceDocuments/ucm080564.htm

Accuracy of automatic AST devices (ISO 20776-2:2007)

Data shall be analyzed by using the appropriate interpretive breakpoints

Essential agreement (±

1 dilution):

≥

90%

Category agreement (interpretive results, SIR) ≥

90%

Major discrepancies (false resistance): ≤

3%* *based on the no. of susceptible organisms tested

Very major discrepancies (false susceptibility): ≤

3%****based on the no. of resistant organisms tested

Reproducibility

(±

1 dilution and/or SIR results): ≥

95%

***for any genus or species tested


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. International Standard ISO 20776-2:2007, ISO, Geneva.

Assessment of the PHOENIX system and EUCAST breakpoints for Assessment of the PHOENIX system and EUCAST breakpoints for antimicrobial susceptibility testing against contemporary isolatantimicrobial susceptibility testing against contemporary isolates es

expressing relevant resistance mechanismsexpressing relevant resistance mechanisms

MI Morosini, M García-Castillo, R Cantón, Vienna, 20th ECCMID, 2010

Objective:-

To evaluate the accuracy of the PHOENIX system using EUCAST

criteria

PHOENIX system: UNMIC/ID-62 Gram negative panelsPMIC/ID-53 Gram positive panels

Comparator: routine or historical data obtained using CLSI guidelinesdiscrepant results resolved using Etest

Bacterial isolates:-

150 fresh consecutive isolates (51 Enterobacteriaceae, 40 P. aeruginosa;

30 S. aureus, 20 Enterococcus spp.)-

93 stored isolated with well characterized resistance mechanisms

-

96 ESBL and 50 MBL producing Enterobacteriaceae-

10 MLB producing P. aeruginosa

- 20 MRSA,

17 VRE

Essential agreement: results within ±

1 log2

dilution

Error rates: -

Minor error 1) the comparator/reference result is resistant (R) or

susceptible (S) and the test result is intermediate (I)2) the comparator/reference result is I and the test device

result is S or R

-

Major error the comparator/reference result is S and the test device is R

-

Very major error the comparator/reference result is R and the testdevice is S

Categorical agreement, concordance between two data set in theclassification of an isolate in SIR category regarding a specific antibiotic


expressing relevant resistance mechanismsexpressing relevant resistance mechanismsMI Morosini, M García-Castillo, R Cantón

Hospital Universitario Ramón y Cajal. Madrid. Vienna, 20th ECCMID, 2010

Fresh isolates(n=150)

Isolates with known resistance phenotypes

(n=193)

Categorical agreement 96.0% 95.5%

Interpretive discrepancies

-

minor discrepancies 0,8% 3,4%

-

Major discrepancies 0,6% 1,9%

-

Very major discrepancies 2,3% 0,8%







Grupo Total test

categorical agreement

(%)

Minor(%)

Major(%)

VeryMajor (%)

Essential agreement

(%)Enterobacteriaceae 1970 92.8 5,2 1,3 0,6 95,4

P. aeruginosa 480 95,4 1,5 0,4 2,7 97,3

S. aureus 340 98,8 0,9 0 0,3 97,6

Enterococcus spp. 229 97,4 0,4 0,4 1,7 94,7




AgentMIC distribution (Phoenix) No. of error rates

>-2 -2 -1 0 1 2 >+2 Minor Major Very MajorAMC 2 3 3 51 24 13 17 7PTZ 96CTX 8 2 82 4 3CAZ 3 2 7 67 15 1 1 16 1IMI 12 83 1 1

MER 2 93 1 1CIP 2 5 1 75 8 5 9GEN 1 1 94 2TOB 96SXT 2 1 92 1 1

ESBL-producingEnterobacteriaceae(n=96)




AgentMIC distribution (Phoenix) No. of error rates

>-2 -2 -1 0 1 2 >+2 Minor Major Very MajorAMC 50PTZ 48 2CTX 50CAZ 50IMI 5 15 19 4 7 13

MER 6 3 3 31 4 3 15CIP 5 2 8 34 1 14 1GEN 1 10 37 1 1TOB 2 1 8 38 1 11 1SXT 1 2 47

Carbapenemase producingEnterobacteriaceae(n=50)


assessment of the Phoenix system & EUCAST breakpoints

Madrid*(393 isolates)

Siena**(362 isolates)

Essential agreement (±1 log2

) 96.0% 99.1%

Categorical agreement (S/I/R) 95.8% 96.2%

Interpretive discrepancies

-

minor discrepancies 2.4% 2.8%

-

Major discrepancies 1.2% 0.8%

-

Very major discrepancies 1.1% 1.3%

*Morosini, García-Castillo, Cantón. Ramón y Cajal University Hospital. Madrid (Spain)**Giani, Conte, D’Andrea, Rossoloni. University of Siena (Italy)

Posters presented at 20th ECCMID, 2010


Concluding remarks

Automatic antimicrobial susceptibility testing systems are part ofclinical microbiology laboratories

Automatic systems available in Europe have incorporated the EUCAST breakpoints,

At present, Phoenix system is one of the system that moreadequately accomplish the EUCAST criteria

Evaluation of Phoenix system in two different European countriesshows that :

-

this system fulfill FDA and ISO accuracy performance requirements-

discrepant results might appear in isolates with enzymatic/heteroresistance mechanisms

Do your best... but better with EUCAST


http://www.eucast.org/

Evaluación del sistema de identificación y

sensibilidad BD Phoenix de acuerdo al

standard EUCAST

EUCAST: Qué, por qué, cómo y cuándo: las claves del éxito

Malaga, 2 de junio, 2010

Departamento de Microbiología IIUniversidad Complutense. Madrid

Hospital Universitario Ramón y CajalSERVICIO DE MICROBIOLOGÍA Y PARASITOLOGÍA

Dr. Rafael Cantón

http://www.ucm.es/info/farmacia/Farma3.htm