Extended spectrum beta-lactamase (ESBL)-producing E.coli increased last year in imported broiler meat, according to a study in Denmark.
From meat samples, the highest occurrence of ESBL-producing E.coli was found among imported broiler meat (61%); an increase compared with 2011.
The occurrence of ESBL-producing E.coli in Danish broiler meat (36%) was at the same level as 2011.
8% of pigs at slaughter were found with ESBL-producing E.coli, which was higher than in 2011, but lower than in 2010.
Reason for resistance
The use of cephalosporins for broilers is considered the primary reason for the development of ESBL resistance, according to the Danish Integrated Antimicrobial Resistance Monitoring and Research Programme (DANMAP).
Cephalosporins have not been used in Danish broiler production in the past ten years but it is thought that imported parent animals may spread the ESBL bacteria.
ESBL-producing bacteria have the same genes, plasmids and clones of E.coli isolates originating from animals and isolates involved in human infections, suggesting a zoonotic link, according to studies.
The occurrence of Enterobacteriaceae resistant to carbapenems is a growing threat in human medicine because carbapenems are the last line of defence for treatment of infections caused by multidrug resistant Gram-negative bacteria in humans, according to the European Food Safety Authority (EFSA).
Multi-resistant S. Typhimurium increased in pigs, pork and humans because of an increasing prevalence of monophasic S.Typhimurium that have a strong tendency to be multi-resistant.
Resistance to seven of the 16 tested compounds was higher among travel-associated cases than domestic human cases, including resistance to fluoroquinolone, said DANMAP.
Among all the Salmonella isolates from Danish pigs and pork, high levels (28% to 41%) of resistance to ampicillin, streptomycin, sulfonamide, and tetracycline were found.
None of the isolates were resistant to cephalosporins (ceftiofur, cefotaxime) or quinolones (ciprofloxacin, nalidixic acid).
The most common serotypes from Danish pigs and pork were S. Derby (47% and 38%), S. Typhimurium including the monophasic variants (39% and 34%) and S. Infantis (5% and 7%).
Campylobacter resistance remains same
Resistance among Campylobacter jejuni isolates from Danish broilers and cattle and Campylobacter coli from Danish pigs remained at the same levels as in 2011.
The level of fluoroquinolone (ciprofloxacin) resistance in C. jejuni is still higher among isolates from imported broiler meat compared with isolates from Danish broiler meat, and among C. jejuni from travel-associated cases compared with domestic cases.
Consumption of antimicrobial agents in 2012 amounted to 112.3 tonnes of active compounds, a 4% increase compared with 2011.
Pigs accounted for 76%, cattle for 11%, fur animals for 5%, aquaculture for 3%, and poultry for 1% of the total veterinary consumption of antimicrobials measured in kg active compounds.
The remaining 4% was used in companion animals and others, added the report from the National Food Institute, Technical University of Denmark and Statens Serum Institut.