EARSS news nr. 1/03 - ECDC

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EARSS news nr. 1/03 - ECDC

6.2 Streptococcus pneumoniae (SPN)

resistance monitored by EARSS

For almost four years (1999-2002, till 3rd quarter) invasive SPN

isolates have been reported to EARSS from by now 27 countries.

From the total number of 18,809 invasive S. pneumoniae isolates

(3,790, 5,380, 6,170, and 3,469 for the respective years), 10%

were reported to be non-susceptible to penicillin (PNSP) and 17%

as non susceptible to erythromycin (ENSP). In the figures below

the proportion (in 6 categories) of PNSP and ENSP is shown per

country. France delivered aggregated data for the first two

quarters of 2001 (n=693). The highest average proportions of

PNSP and ENSP isolates were found for the Mediterranean

countries and the lowest for the more northern countries.

S. pneumoniae clones are often simultaneously resistant to

ß-lactams and macrolides. Indeed, in 10 (AT, BE, BG, ES, FI, FR, IS,

IT, LU, and SK) countries, more than 50% of the PNSP strains were

also resistant to erythromycin.

Figure 1. Proportion of invasive penicillin non-susceptible

S. pneumoniae (PNSP) isolates per country

label

Figure 2. Proportion of invasive erythromycin non-susceptible

S. pneumoniae (ENSP) isolates per country

label

< 1 %

1 - 5 %

5 - 10 %

10 - 25 %

25 - 50 %

> 50 %

no data

< 1 %

1 - 5 %

5 - 10 %

10 - 25 %

25 - 50 %

> 50 %

no data

6

6.3 Quality Assessment exercise

EARSS 2002

The goal of the third external quality assurance (EQA) exercise of

EARSS was the ongoing assessment of comparability in

susceptibility test results across countries and guidelines. A set of

five strains; S. aureus U2A1556 (mecA, penA, rpoB, ant4’), E.

faecium U2A805 (vanB, aph2”-aac6’, ant3”9, erm), E. coli U2A1557

(IRT), E. coli U2A1526 (blaCTX-M, aac3-V, ant3”, gyrA), and

S. pneumoniae (penR, aph3’-III, ant3”9, ermB, cat, parC, TpRSuR),

were kindly provided by CRAB (Centre National de Référence des

Antibiotiques) and distributed by UK-NEQAS (United Kingdom

National External Quality Assessment Scheme) through the

national distributors to the laboratories participating in EARSS.

The laboratories were asked to report methods and guidelines

used for speciation, MIC-determination (when performed) and

clinical susceptibility categorisation (S, I and R). Results were

considered ‘concordant’ if the reported categorisation agreed

with the interpretated result of three reference laboratories,

which are displayed in Table 1.

Overall, 640 (93%) of 690 laboratories from 26 countries reported

results. Most of them used NCCLS guidelines (72%). In Figure 3 the

average and range of the overall concordance of antimicrobial

test results are given for all participating laboratories, specified

for every control strain. For the E. faecium, the overall concordance

was high for amoxicillin/ampicillin (98%), gentamicin

(98%), vancomycin (90%) and teicoplanin (96%) but low for species

identification (87%). For the S. pneumoniae the overall

concordance was high for oxacillin (98%), penicillinG (98%),

erythromycin (95%) and clindamycin (93%) but low for

ceftriaxone/cefotaxime (48%). Both E. coli strains had a high

concordance for amoxicillin/ampicillin (98-100%), gentamicin

(99%) and ciprofloxacin (96-100%). Importantly, the concordance

for detection of ESBL production was high (93-95%). For the

S. aureus the concordance was high for oxacillin/methicillin

(94%), teicoplanin (99%) and vancomycin (99%).

The third EQA exercise of EARSS had again a high overall

concordance, confirming that the resistance surveillance as

monitored by EARSS is valid. However, the 13% misidentification

of the E. faecium should be dealt with by the laboratories. The

low concordance for the susceptibility of the S. pneumoniae to

ceftriaxone/cefotaxime most probably occurred because the low

breakpoint (S

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