EQAS Enterococci, Staphylococci and E. coli EURL workshop, April, 11 Lourdes García Migura Main objectives of the EURL EQAS s To improve the comparability of antimicrobial susceptibility testing (AST) data To harmonise the breakpoints/epidemiological cut off values To assess the quality of AST in European laboratories and identify possible barriers To support laboratories in performing, evaluating and if necessary improving the quality of AST Participants in the enterococci, staphylococci and E. coli EQAS, 9 3 Participants in EQAS Participants in EQAS 9 EU countries not EU countries participating not participating 3 3 Number of participating labs Number of participants 1 7 9 Enterococci Staphylococci E. coli 1
Methods for EQAS 9 Eight strains of enterococci, staphylococci and E. coli, respectively were selected New participants were provided with the reference strains, E. faecalis ATCC 91, S. aureus ATCC 93, S. aureus ATCC 913 and E. coli ATCC 9 for QC testing AST guidelines were set according to the CLSI. MIC results were interpreted using the epidemiological cut off values set by EUCAST (www.eucast.org), recommended by EFSA and described in the protocol Participants using disk diffusion were advised to interpret the results according to their individual breakpoints Results were categorized as resistant or susceptible Analysis of data based on these agreements During the passed EURL-AR Workshop () the network agreed upon the following decisions for EQAS 9: The accepted deviation for each laboratory is set up at % Results should be further analysed (possibly ignored) when more than % are incorrect (strain/antimicrobial combination) AST data that the MS report to EFSA is based on the interpretation of the results, the EQAS evaluates interpretation EQAS 9 versus previous EQAS Percentage of deviation 9 7 3 1 Enterococcus Staphylococcus E. coli EQAS 7 EQAS EQAS 9 EQAS
Deviation by species comparing the AST methods 1 1 MIC DD Total deviation Pe ercentage of deviation Enterococci Staphylococci E. coli 1 MIC 1 MIC MIC DD 7 DD DD Significant differences were observed in the results obtained depending of the AST method used (p <.1) Enterococci trial - results Results that have 7% mitted from the evaluation Enterococci trial - results 9 Deviation by strain and AST method 3 MIC DD TOTAL deviation Percentage of d 1 ENT.,1 ENT., ENT.,3 ENT., ENT., ENT., ENT.,7 ENT., Enterococci strains 3
Enterococci trial - results Deviation by antimicrobial tested deviation Percentage of d 1 1 1 AMP* CHL* CIP ERY* GEN* LZD* STR* SYN* TET* VAN* Antimicrobials *Antimicrobials recommended by EFSA for monitoring antimicrobial resistance across the EU Enterococci trial - results 11 Deviation by laboratory 3 EFSA antimicrobials All antimicrobials % acceptance limit f deviation Percentage of 1 * * 1* 39 37 3 19 9 1* 33 9 1 17 1 1 3 Laboratory number *Laboratories performing DD for AST 1 Enterococci trial - results 1 1 boratories Number of lab 1-1 >1-3 >3- >-7 >7-9 >9-11 >11-1 >1- >- 1 NRLs Interval of deviation NRLs
QC- STRAIN MIC E. faecalis ATCC 91 MIC deviations Min Max Antimicrobial /Total no. of QC range MIC value value tests Ampicillin /1. -. Chloramphenicol /1-1 Ciprofloxacin /1. -. Erythromycin /17 1-1 Gentamicin /17-1 1 Linezolid /1 1-1 Streptomycin /17-3 1 Synacid /9 - Tetracycline /17-3 3 Vancomycin /17 1-17 participants 1 correct tests performed Summarizing enterococci trial For the first time, the total deviation for the enterococcal trial falls below % 3/ laboratories performing disk diffusion obtained deviations higher than the % 3/9 antimicrobials recommended by EFSA failed to produce % of correct results Ampicillin: ENT.,/ampicillin, ECOFF ampicillin mg/l, the expected MIC = mg/l Synacid: # and #1 performing disk diffusion Gentamicin: # Deviations were mainly caused by laboratories performing DD for AST One participant clustered in the interval between %-% deviation and was considered an outlier Staphylococci trial - results Results that have NOT been omitted from the evaluation 1 aboratories aboratories number of l number of la 1 1 categorised Categorised as as susceptible categorised as as resistant. 1 1 MIC values ST., MIC values ST.,
Deviation by strain Staphycocci trial - results 1 1 MIC DD TOTAL ge of deviation percentag ST.,1 ST., ST.,3 ST., ST., ST., ST.,7 ST., Staphylococci strains No significant differences were observed in results obtained by the two different AST methods (p =.9) Staphylococci trial - results 17 Deviation by antimicrobial tested f deviation Percentage of 1 1 1 FOX CHL CIP ERY FFN GEN PEN STR SMX TET TMP Antimicrobials Staphylococci trial - results 1 Deviation by laboratory 9 f deviation Percentage of 7 3 1 39 1 3 13* 33 3 11 * 1* 9* 1 1* * 19 3 1 9 1* 17 31 37 *Laboratories performing DD for AST Laboratory number
19 Staphylococci trial - results 1 of laboratories Number o -1 >1-3 >3- >-7 >7-9 Intervals of deviation NRLs NRLs Methicillin Resistant S. aureus (MRSA) ST.,1, ST., and ST., were confirmed to be methicillin resistant % correct results Participant #39 did not perform the test QC strain - S. aureus ATCC 93 by DD Antimicrobial Deviation/Total Min Max QC range no. of tests value value Cefoxitin 1/ 3-9 3 Chloramphenicol /3 1-1 Ciprofloxacin / -3 3 9 Erythromycin / -3. Florfenicol /3 None 9 Gentamicin 1/ 19-7 19 3 Penicillin / -37 3 37 Streptomycin / 1-1 Sulfisoxazole /3-3 3 Tetracycline / -3 33 Trimethoprim /3 19- A total of 3 correct tests performed in this strain out of 7
S. aureus ATCC 913 by MIC Antimicrobial Deviation/Total no. of tests QC range Min value Max value Cefoxitin /13 1- Chloramphenicol /1-1 Ciprofloxacin /17.1-..1. Erythromycin /.-1. 1 Florfenicol /9 - Gentamicin /19.1-1. Penicillin /1.-. Sulfisoxazole / 3-1 3 1 Tetracycline /.1-1. Trimethoprim 1/1 1-. Total number of test was 17 of which 3 were incorrect Summarizing staphylococci trial For the first time in this staphylococci iteration, no significant differences were observed between the two AST methods. All of the strains and antimicrobials tested presented deviations below.3% except the combinations ST.,/ciprofloxacin and ST.,/ciprofloxacin Four laboratories clustered outside the %, most of the participants grouped in the deviation interval between 1% and 3%. All the laboratories identify correctly the MRSA strains except one that didn t performed the test Laboratories performing DD on S. aureus ATCC 93 produced a deviation of.% whereas laboratories performing MIC obtained 1.7%. E. coli trial - results Results that have NOT been omitted from the evaluation
E. coli trial - results Deviation by strain and AST method 1 1 1 MIC DD TOTAL of deviation Percentage 1 EC.,1 EC., EC.,3 EC., EC., EC., EC.,7 EC., E. coli strains Significant difference observed depending of method used for AST (p<.1) E. coli trial - results Deviation by antimicrobial tested 1 of deviation Percentage AMP* CTX* CAZ XNL CHL CIP* FFN GEN* NAL* STR SMX* TET* TMP* Antimicrobials *Antimicrobials recommended by EFSA for monitoring antimicrobial resistance across the EU Cephalosporin resistant strains EC., EC., EC,.7 bla CTX-M-1 bla CTX-M-1 bla CMY- - #39 did not perform any of the confirmatory tests -/ labs failed to identify ESBL producing organisms -#3 obtained MIC value for cefotaxime.1 mg/l instead of mg/l and ceftazidime. mg/l instead of 3 mg/l -# obtained MIC for cefotaxime.1 mg/l instead of mg/l, they performed the two confirmatory tests on the strain, both of them were negative for ESBL production 9
AmpC strain - 7/ labs failed to identify the ampc strain EC.,7 -# obtained susceptible values for all cephalosporins tested -#9 susceptible value for cefoxitin, resistant for CTX and CAZ and did not find synergy (CTX/CL:CTX) - #1, # and #3 identified the strain as ESBL and ampc -#1 did not perform confirmatory test for ESBL -# obtained an increase in the diameters ( mm) for the two confirmatory tests (CAZ:CAZ/CL and CTX:CTX/CL) -#3 reported increase in the MIC ratio only for one of the confirmatory test (CAZ/CL:CAZ) -# and #3 performed all tests and got correct results even for cefoxitin but fail to interpret them correctly -# identified strain EC.,1 as an ampc. They obtained MICs of 1 mg/l, mg/l and >1 mg/l for ceftazidime, cefotaxime and cefoxitin Deviation by laboratory E. coli trial - results 9 3 3 EFSA antimicrobials All antimicrobials % deviation Percentage o f deviation 1 39 * 9 3 1*19 1*11 1 1* 33 9 37 1 1 1 17 3 3 3 Laboratory number *Laboratories performing DD for AST 3 E. coli trial - results of laboratorie Number 1 1 1 1-1 >1-3 >3- >-7 >7-9 >9-11 >11-1 >1- >- 7 NRLs Interval of deviation NRLs
QC strain - E. coli ATCC 9 by DD - tests and were incorrect (1.% deviation) Antimicrobial Deviation/Total no of tests QC range Min Max value value Ampicillin / 1-1 Cefotaxime 1/ 9-3 3 Cefoxitin 1/3 3-9 3 Ceftazidime 1/3-3 7 33 Ceftiofur 1/3-31 7 33 Chloramphenicol 1/3 1-7 Ciprofloxacin / 3-3 Florfenicol 1/ - 3 33 Gentamicin / 19-. Imipenem 1/ -3 9 Nalidixic acid / - 7 Sulfisoxazole / 1-3 1 3 Tetracycline /3 1- Trimethoprim 1/ 1-17 QC strain - E. coli ATCC 9 by MIC Antimicrobial Deviation/Total no of tests QC range Min value Max value Ampicillin 1/ - 1 Cefotaxime 3/.3-.1. Cefoxitin / - Ceftazidime /.-..1. - test performed of which 7 were incorrect Ceftiofur Chloramphenicol /3 /.-1 -.. (deviation.%) Ciprofloxacin /.-.1..3 Florfenicol /1 - Gentamicin 1/.-1. Imipenem /.-..1. Nalidixic acid / 1-1 Streptomycin /3-1 Sulfisoxazole /17-3 1 Tetracycline /.- 1 Trimethoprim /.-. 1 Summarizing E. coli trial Deviations in EFSA recommended antimicrobials remained lower than 3% Deviations were mainly caused by laboratories performing DD for AST They majority clustered in the interval of deviation between % and 1% Two laboratories obtained deviations above the % acceptance limit and one of them clustered has been identified as an outlier Deviations for ESBL and ampc detection are still high For E. coli ATCC 9 the percentage of results within range for all tests performed by disk diffusion was 3.3% compared to the 97.% obtained by MIC 11
Conclusions 3 Performance has improved for the enterococci trial There is still a significant difference in the quality of results obtained by NRLs performing MIC when compared to those performing DD % correct results in detection of MRSA the number of laboratories failing to identify the strains resistant to cephalosporins has been remarkably high, especially for the ampc strain Main cause of deviations Strains with expected MIC values close to the epidemiological cut off values to define them as resistant Laboratories performing disk diffusion two outliers have been identified, one for enterococci trial and one for the E. coli trial Thank you for your attention 1