A pan-European survey of antimicrobial susceptibility towards human-use antimicrobial drugs among zoonotic and commensal enteric bacteria isolated from healthy food-producing animals.

OBJECTIVES: The aim of the study was to study antimicrobial susceptibility in Escherichia coli, Salmonella, Campylobacter and Enterococcus recovered from chickens, pigs and cattle using uniform methodology. METHODS: Intestinal samples were taken at slaughter in five EU countries per host and bacteria isolated in national laboratories. MICs were determined in a central laboratory of key antimicrobials used in human medicine. Clinical resistance was based on CLSI breakpoints and decreased susceptibility on EFSA epidemiological cut-off values. RESULTS: Isolation rates from a total of 1500 samples were high for E. coli (n=1465), low for Salmonella (n=205) and intermediate for Campylobacter (n=785) and Enterococcus (n=718). Resistance prevalence varied among antibiotics, bacteria, hosts and countries. For E. coli and Salmonella, clinical resistance to newer compounds (cefepime, cefotaxime, ciprofloxacin) was absent or low, but a decreased susceptibility was apparent, particularly in chickens. Clinical resistance to older compounds (except colistin and gentamicin) was variable and higher. For Campylobacter jejuni from chickens, ciprofloxacin resistance was markedly higher than in isolates from cattle. Clinical resistance to erythromycin was absent for both hosts; decreased susceptibility very low. Similar trends were determined for Campylobacter coli, but C. jejuni was less resistant. None of the enterococcal strains was resistant to linezolid, but a few displayed resistance to ampicillin or vancomycin. Resistance prevalence to quinupristin/dalfopristin was clearly higher. CONCLUSIONS: Antimicrobial resistance among enteric organisms in food animals varied among countries, particularly for older antimicrobials, but clinical resistance to essential compounds used to treat disease in humans was generally zero or low. In the absence of clinical resistance to newer compounds in E. coli and Salmonella, the apparent decreased susceptibility should be monitored carefully.

A European survey of antimicrobial susceptibility among zoonotic and commensal bacteria isolated from food-producing animals.

OBJECTIVE: To study antimicrobial resistance in zoonotic bacteria isolated from food animals in different countries using uniform methodology. METHODS: Samples were taken at slaughter from chickens, pigs and cattle in four EU countries per host. Escherichia coli (indicator organism; n = 2118), Salmonella spp. (n = 271) and Campylobacter spp. (n = 1325) were isolated in national laboratories and MICs tested in a central laboratory against, where appropriate, ampicillin, cefepime, cefotaxime, ciprofloxacin, chloramphenicol, erythromycin, gentamicin, nalidixic acid, streptomycin, tetracycline and trimethoprim/sulfamethoxazole. RESULTS: Isolation rates were high for E. coli, low for Salmonella and intermediate for Campylobacter. MIC results showed resistance prevalence varied among compounds, hosts and countries. For E. coli and Salmonella, resistance to newer compounds (cefepime, cefotaxime, ciprofloxacin) was absent or low, but to older compounds (except gentamicin), resistance was variable and higher. E. coli isolates from Sweden showed low resistance, whereas among isolates from Spain (pigs), resistance to ampicillin, chloramphenicol, streptomycin, tetracycline and trimethoprim/sulfamethoxazole was higher; the UK, France, the Netherlands, Germany, Italy and Denmark were intermediate. For Campylobacter spp. isolates from chickens, nalidixic acid and ciprofloxacin resistance was >30% in France and the Netherlands, >6% in the UK and zero in Sweden. Nalidixic acid resistance was high in cattle (20%-64%), whereas ciprofloxacin resistance was markedly lower in cattle, variable in pigs (3%-21%) and highest in Sweden. Generally, Campylobacter coli was more resistant than Campylobacter jejuni. CONCLUSION: Antimicrobial resistance among enteric organisms in food animals varied among countries, particularly for older antimicrobials, but resistance to newer compounds used to treat disease in humans was generally low.