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INTRODUCTION Chloramphenicol is a broad spectrum antibiotic, which is illegal to use for treatment of food producing animals due to its toxic effects on the bone-marrow in humans. Chloramphenicol has been found to occur naturally in straw. Since straw is the most common bedding material for pigs in Sweden, we investigated if low daily doses of chloramphenicol (4, 40 and 400 μg/pig) fed orally during 14 days, could result in chloramphenicol residues in pigs and, if so, would still be detectable after a 7 days withdrawal period. CHLORAMPHENICOL IN PIG TISSUES, PLASMA AND URINE AFTER LOW ORAL DOSES MAY 23-25, 2016 EURORESIDUE VIII, EGMOND AAN ZEE, NL EXPERIMENTAL • Twenty four pigs, weighing 23-27 kg at the start of the experiment, were kept in 4 groups of 6 pigs each. • Chloramphenicol dissolved in absolute ethanol and absorbed on cubes of sugar with the daily doses of 4, 40 and 400 μg of chloramphenicol respectively were administered to the pigs in respective group. • The pigs were kept on concrete floor with sterilized wooden chips as bedding and were fed commercial feed which had been showed to be free from chloramphenicol. ANALYSES • Muscle and urine were analysed both at RIKILT and NFA using similar but not identical procedures. Liver, kidney and plasma were analysed only at RIKILT. • In both laboratories, chromatography was performed on an ACQUITY UPLC system (Waters, Manchester, UK) equipped with an ACQUITY UPLC BEH C18 analytical column (Waters, Manchester, UK). • Detection was carried out using a Waters model Xevo TQS triple quadrupole mass spectrometer in the negative electrospray ionization (ESI) mode. CONCLUSIONS Chloramphenicol in very low doses (4 μg/pig daily) which may be naturally occurring, can be absorbed by pigs resulting in positive findings above the RPA in urine. Administration of approximately 10 times higher doses are required to find corresponding amounts in plasma and kidney and even higher doses to exceed the RPA in muscle. RESULTS • A dose related increase of residues was found in muscle, plasma, kidney and urine, but no chloramphenicol was found in liver (LOD <0.05 μg/kg) . • In the lowest dose group, residues were over the RPA only in urine (median concentration 6 μg/kg). • One week after last dose, chloramphenicol levels above RPA could only be found in urine from the highest dose group (median concentration 1.2 μg/kg). • The results of the analyses from NFA and RIKILT showed a good conformity. • The methods for muscle and urine used at NFA were more sensitive, probably because of a more extensive sample preparation. TIMELINE 1 National Food Agency P.O.Box 622 SE-751 26 UPPSALA Sweden 2 RIKILT – Wageningen UR P.O.Box 320 6700AE Wageningen The Netherlands 3 National Veterinary Institute SE-751 89 UPPSALA Sweden 0 50 100 150 200 250 300 350 0 0,5 1 1,5 2 2,5 3 3,5 4 4,5 4μg/day 40 μg/day 400 μg/day μg/kg urine μg/kg organ Muscle Kidney Plasma Urine © Erik Nordkvist BITTE ASPENSTRÖM- FAGERLUND 1 ERIK NORDKVIST 3 ANNA TÖRKVIST 1 PER WALLGREN 3 RON HOOGENBOOM 2 BJORN BERENDSEN 2 KRISTINA GRANELLI 1 Median content of choramphenicol in pig organs and urine after oral intake in sub-therapeutical doses.
