EFSA Reports on Antimicrobial Resistance in Zoonotic Bacteria Over 2004-2007

During the years 2004 to 2007, 26 Member States submitted information on the occurrence of antimicrobial resistance in zoonotic bacteria originating from poultry, pigs and cattle as well as from meat to the European Commission and the European Food Safety Authority (EFSA).

6 May 2010 --- Zoonoses are infections and diseases that are transmissible between animals and humans. Infection in humans can be acquired directly from animals, or through the ingestion of contaminated foodstuffs. Severity of zoonotic diseases in humans varies from mild symptoms to life-threatening conditions. Zoonotic bacteria that are resistant to antimicrobials are of special concern since they might compromise the effective treatment of infections in humans. In order to follow the occurrence of antimicrobial resistant zoonotic bacteria in animals and food, information is collected and analysed from all European Union Member States.

During the years 2004 to 2007, 26 Member States submitted information on the occurrence of antimicrobial resistance in zoonotic bacteria originating from poultry, pigs and cattle as well as from meat to the European Commission and the European Food Safety Authority (EFSA). In addition, Norway and Switzerland provided information for the report. The reported information covered resistance to 51 antimicrobial substances. Assisted by its contractor, the Technical University of Denmark, EFSA analysed the data, the results of which are published in this Community Summary Report. Information on antimicrobial resistance was reported regarding Salmonella, Campylobacter, indicator (commensal) Escherichia coli and indicator (commensal) enterococci isolates from animals and food.

The Member States reported both quantitative and qualitative data on antimicrobial resistance and both types of data is included in the report giving priority to quantitative data. A special effort was made to analyse the quantitative information reported on antimicrobial resistance. These data, expressed either as Minimum Inhibitory Concentrations or as disk inhibition zones, were interpreted using epidemiological cut-off values defining the resistance. This makes the data more comparable between reporting countries. The number of Member States reporting quantitative data on antimicrobial resistance increased from 18 Member States in 2004 to 21 Member States in 2006.

Resistance to antimicrobials was commonly found among the Salmonella, Campylobacter and the indicator E.coli and enterococci isolates from animals and food in the EU. For some tested antimicrobials, large differences in the occurrence of resistance over time were observed between Member States. These observations may reflect real differences in resistance situations in countries, but may also be partly due to differences in the monitoring and reporting systems in place and in the case of Salmonella, due to serovars present in the country. At Member State level the occurrence of antimicrobial resistance over time remained, in most cases, relatively stable over the reporting years. However, some decreases and increases in resistance were observed.

The proportion of Salmonella and E. coli isolates resistant to ampicillin, sulfonamide and tetracycline varied between 5% and 68% among the isolates from poultry, pigs and cattle in the reporting Member State group. Some Member States reported a high occurrence of fluoroquinolone resistance in Salmonella isolates from poultry and in Campylobacter isolates from poultry, pigs and cattle as well as from meat. At Member State group level these resistance levels varied from 5% to 38% and from 20% to 64% for the Salmonella and Campylobacter isolates, respectively, during the years 2004 to 2007. This is of concern, since fluoroquinolones are defined as critically important antimicrobials in human medicine. Some Member States also reported resistance to third generation cephalosporins and macrolides, which are also antimicrobial groups of critical importance in human medicine.

The occurrence of resistance to tetracycline, ampicillin and sulphonamide in Salmonella isolates from fowl was at a lower level than in Salmonella isolates from pigs and cattle, whereas quinolone resistance levels were higher in Salmonella isolates from fowl.

In indicator E. coli isolates from fowl and pigs, large variations in the reported resistance levels were observed between Member States. In cattle, the occurrence of resistant E. coli isolates was lower compared to fowl and pigs. Vancomycin resistance was still reported in some enterococci isolates from fowl, pigs and cattle even though avoparcin, a similar substance used in animals, had already been banned in 1997.