Over 400 laboratories participate in EARSS (European Antimicrobial Resistance Surveillance System) and send data to the National Institute of Public Health and the Environment (RIVM) in The Netherlands. Data on about 14 000 isolates of Staphylococcus aureus from blood and on about 6000 isolates of Streptococcus pneumoniae infections are expected each year. Data published after the 18 month feasibility phase suggest that methicillin resistance among bloodstream S. aureus isolates is commoner in countries of southern than of northern Europe.

The European Commission has responded to the emerging problem of antimicrobial resistance by funding the European Antimicrobial Resistance Surveillance System (EARSS), coordinated by the Dutch National Institute of Public Health and the Environment (RIVM; Rijksinstituut voor Volksgezondheid en Milieu). In 1997 a prioritisation exercise was carried out among the heads of centres with responsibilities for surveillance at national level in the member states of the European Union (Charter group). Antimicrobial resistance ended up in the top five areas in communicable disease surveillance for which the development of collaborations was deemed a high priority, along with outbreaks of gastroenteritis/food poisoning, Creutzfeldt-Jakob disease/other prion disease, serious imported diseases, and legionellosis (1).

EARSS aims to produce more comparable and reliable resistance data than were previously available, through the collaboration of a network of national surveillance systems in all EU member states, plus Iceland and Norway (table 1) . EARSS takes into account laboratory methods as well as epidemiological principles to provide incidence figures for and trends in antimicrobial resistance, describe regional differences, and feed back basic data that will facilitate specific studies to assess risk factors. EARSS started on 1 April 1998, with an 18 month feasibility phase. Over 400 laboratories have agreed to take part in EARSS and send data via national coordinators to the central database at RIVM. The catchment population of these laboratories is about 60 million people, which is almost a third of the combined population of those countries. To our knowledge this is the largest such network. Data on about 14 000 isolates of Staphylococcus aureus from blood and on about 6000 isolates of Streptococcus pneumoniae from blood and cerebrospinal fluid (CSF) are expected each year. The report of the feasibility phase released in December 1999 (http://www.earss.rivm.nl) described the progress in setting up the system and the first results (2).

Table 1.  Participating countries, national co-ordinators and collaborators in EARSS

Austria (AT)

H. Mittermayer / W. Koller

Belgium (BE)

H. Goossens / F. van Loock

Denmark (DK)

T. Soerensen / D. Monnet

Finland (FI)

P. Huovinen / O. Lyytikäinen

France (FR)

P. Courvalin / H. Aubry-Damon

Germany (DE)

W. Witte / F. Tiemann

Greece (GR)

N. Legakis / A. Vatopoulos

Iceland (IS)

K. Kristinsson / H. Briem

Ireland (IE)

O. Murphy / D. O’Flanagan

Italy (IT)

G. Cornaglia / M.L. Moro

Luxembourg (LU)

R. Hemmer

Netherlands (NL)

H. de Neeling / W. Goettsch

Norway (NO)

E. Hoiby / P. Aavitsland

Portugal (PT)

M. Caniça / M. Paixão

Spain (ES)

F. Baquero / J. Campos

Sweden (SE)

O. Cars / B. Olsson-Liljequist

United Kingdom (UK)

A. Johnson / M. Wale

Collaborators :

WHO

R.Williams

ESCMID

I. Phillips / M. Struelens

In the feasibility study microbiologists and epidemiologists from participating countries decided to collect resistance data on invasive Streptococcus pneumoniae and Staphylococcus aureus, using methodology discussed in great detail elsewhere (3). The WHONET application is available for data entry and data are stored in the standardised, validated EARSS data exchange format. At the start of the project a questionnaire was distributed to the laboratories in order to collect information on test methods and denominator data. For quality assurance, it is envisaged that laboratories participating in EARSS will test a special set of strains that will be distributed from a central facility. It is foreseen that data will be shared using the electronic infrastructure ‘Interchange of Data between Administrations’ (IDA) network of the European Union. Feedback - in the form of summary tables and geographical cards – will be available on the internet.

The susceptibility test results for invasive S. aureus presented here are those that were available by January 2000.

By the end of 1999, questionnaires from 283 laboratories had been received. These laboratories serve 450 hospitals, mainly general hospitals (76%) but also academic/tertiary hospitals (20%) and nursing homes (4%). Ninety-five per cent of the 150 laboratories that specified which method they used undertook susceptibility testing of S. aureus against oxacillin and/or methicillin routinely. About half of these laboratories Mueller-Hinton agar (sometimes with salt) and follow the National Committee for Clinical Laboratory Standards (NCCLS) recommended breakpoints. By the end of 1999, laboratories from 12 countries (Belgium, Denmark, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Portugal, Sweden, United Kingdom) were sending data. Susceptibility test results for S. aureus from blood were available from 159 laboratories from 11 countries. About half of the isolates were isolated from patients over 65 years of age. Ninety-five per cent of the patients had been admitted to hospital, which was not surprising as EARSS collects data on invasive isolates only. Table 2 shows the period in which the test results were collected as well as the number of laboratories that sent data and the total number of isolates. The proportion of methicillin resistant S. aureus (MRSA) was calculated for the different countries and ranged from 0% to 53%. A wide gap in the resistance rates between northern and southern Europe was seen. In the northern European countries the resistance rates are generally low and in southern European countries (and Ireland) rates over 40% were reported.

Table 2. Susceptibility test results of Staphyloccocus aureus

Country

Period

Nr Labs

Nr S. aureus

MRSA*

Nr

%

(95% CI)

Denmark

Q4/1998 ; Q1-2/1999

5

502

0

0

Iceland

Q4/1998 ; Q1-2/1999

2

21

0

0

Netherlands

Q1-2/1999

20

495

1

0

(0-1)

Sweden

Q4/1998 ; Q1-3/1999

23

1615

24

1

(1-2)

Finland

Q1-4/1999

11

250

9

4

(1-6)

Germany

Q4/1998 ; Q1-2/1999

15

331

24

7

(5-10)

Luxembourg

Q4/1998 ; Q1-4/1999

1

40

5

13

(2-23)

Italy

Q1-4/1999

46

687

279

41

(37-44)

Ireland

Q1-3/1999

11

306

127

42

(36-47)

Portugal

Q1-3/1999

12

190

94

50

(42-57)

Greece

Q1-4/1998

13

137

72

53

(44-61)

The public health perspective is an added value of EARSS. Resistance rates alone do not necessarily give information on the impact of resistance on public health, so it is important to estimate the incidence of resistant pathogens in a population. Denominator data are needed to calculate incidence figures (hospital admission data for hospital acquired S. aureus and catchment population data for community acquired S. pneumoniae). EARSS is collecting these data and when data over a longer period become available, it will be possible to derive incidence figures and study trends over time.

The feasibility phase yielded a conclusion that EARSS is needed and feasible, and that it must run continuously with guaranteed funding. The number of pathogens under surveillance will be expanded as soon as the data processing has been optimised. EARSS is already acting as a catalyst for national surveillance systems, such as in Ireland (4).

For further information see the EARSS website (http://www.earss.rivm.nl), or contact the project coordinator, S Bronzwaer (info.earss@rivm.nl), or a national coordinator in your country by using the email addresses on the website.

1. Bronzwaer SLAM, Goettsch W, Olsson –Liljequist B, Wale MCJ, Vatopoulos AC, Sprenger MJW. European Antimicrobial Resistance Surveillance System (EARSS): objectives and organisation. Eurosurveillance 1999; 4(4): 41-4

2. Weinberg J, Grimaud O, Newton L. Establishing priorities for European collaboration in communicable disease surveillance. Eur J Public Health 1999; 9: 236-40.

3. EARSS Management Team. Report on feasibility phase EARSS, period: April 1998-September 1999. Bilthoven: RIVM, 1999. (http://www.earss.rivm.nl)

4. Goettsch W, Bronzwaer SLAM, Neeling AJ de, Wale MCJ, Aubry-Damon H, Olsson-Liljequist B, Sprenger MJW, Degener JE. Standardization and quality assurance for antimicrobial resistance surveillance of Streptococcus pneumoniae and Staphylococcus aureus within European Antimicrobial Resistance Surveillance System (EARSS). Clin Microbial Infect 2000; in press.

5. O’Flanagan D. Development of a strategy to combat antimicrobial resistance in Ireland. Eurosurveillance Weekly 1999; 3: 991104. (http://www.eurosurv.org/1999/991104.html)