Salmonella and Campylobacter are showing significant resistance to common antimicrobials, according to an EU report.
The European Food Safety Authority (EFSA) and European Centers for Disease Prevention and Control (ECDC) said that for many antimicrobials the level of resistance varied greatly between different member states and animal production types.
The findings were detailed in the European Union Summary Report on antimicrobial resistance (AMR) in zoonotic and indicator bacteria from humans, animals and food in 2012.
Dr Pierre-Alexandre Beloeil, senior scientific officer at EFSA’s Biological Hazards and Contaminants Unit, told FoodQualityNews.com the findings were expected and not surprising.
“They are interesting results providing a good reflection on how antimicrobial resistance works and it is good to know from a public health perspective.
“Some antimicrobials have been used for years, decades even, and Salmonella and Campylobacter have been exposed for years so resistant strains have been selected over time.
“The situation has not changed a lot from year to year. Trends appear over a number of years and some increase but from one year to another there is no major change.”
Resistance levels to ciprofloxacin were influenced by the interpretive criteria used in each country, resulting in higher resistance levels in countries using more sensitive criteria.
The introduction of harmonised EUCAST methods and interpretive criteria in member states was welcomed and supported by ECDC.
Guidelines for AMR were updated in 2012 and the EU Commission used those as a basis for revising legislation to harmonise monitoring and comparability in the data of member states.
Beloeil said they came into force at the start of the year and by 2015 or 2016 better quality data should be collected.
“The key aspects were broadening the scope of AMR, the representation and relevance of the data collected, to get better comparability and more in-depth analysis of resistance,” he said.
“[The aim is] to observe the disparity between member states and use the data to look at the risk.”
Critically important antimicrobials
Combined resistance to critically important antimicrobials remains low but the fact that antimicrobial resistance was commonly detected is a cause for concern.
If bacteria become clinically resistant to several antimicrobials (multidrug-resistant), treating the infections they cause can become more difficult or even impossible.
The development of antimicrobial resistance in bacteria in animals and food can compromise the effective treatment of human infections, as resistant bacteria and resistance genes may be transferred to humans from animals and food.
Beloeil said that the findings were important to gain relevant risk assessment data.
“This gives us targeted interventions to better strengthen antimicrobials to avoid misuse in animals and to measure the effects of interventions and mitigation strategies.”
Clinical resistance’ in human Salmonella isolates was high for ampicillin (27.6%), streptomycin (23.6%), sulfonamides (28.9%) and tetracyclines (30%), and moderate for nalidixic acid (14.4%), and high levels of multi-resistance were observed in some countries (28.9% overall).
The joint report shows that clinical resistance in humans to commonly used antimicrobials in Salmonella spp. isolates was frequently detected at the EU level, with almost half of the isolates being resistant to at least one antimicrobial, and 28.9% of isolates being multidrug-resistant.
However, levels of clinical resistance and co-resistance in Salmonella spp. isolates to critically important antimicrobials were low (0.2% co-resistance across the 12 member states that submitted data).
Invasive Salmonella or Campylobacter were fortunately rare, according to Beloeil.
“Co-resistance to critically important antimicrobials remains low. This means that treatment options for serious infection remain available.”
In Campylobacter spp. isolates from human cases, clinical resistance to common antimicrobials was frequently detected.
Very high proportions of isolates (47.4% EU average) were resistant to the critically important antimicrobial ciprofloxacin with increasing trends observed in several Member States
The ‘clinical resistance’ levels in human Campylobacter isolates were highest for nalidixic acid (48.8%) and ciprofloxacin (47.4%) followed by ampicillin (36.4%) and tetracyclines (32.4%), with high levels of multi resistance observed in some countries.
Resistance to the clinically important antimicrobial erythromycin was low overall (3.1%), but moderately high in C. coli (15.1%), although the number of isolates tested was small.
Fluoroquinolones, such as ciprofloxacin, and third-generation cephalosporins, such as cefotaxime, are considered critically important antimicrobials in treating severe or invasive salmonellosis in humans.
Fluoroquinolones and macrolides, such as erythromycin, are considered critically important for treating severe Campylobacter infections.