| Abstract |
Antibiotics are widely used to cure diseases caused, mainly, by bacteria. In cases of livestock farming that they are used irrationally, residues of these substances present in edible tissues constitute a serious risk for consumers. The aim of the current research was the determination of the levels of sulfonamides, tetracyclines, aminoglycosides, and fluoroquinolones in samples of beef, chicken and pork (muscle, liver, and kidney). The 54 samples were collected from butcheries of Heraklion and Rethymnon, Crete, Greece.
The samples were analysed with Enzyme-linked Immunosorbent Assay (ELISA) and Liquid Chromatography-Electrospray Ionization-Mass Spectrometry (LC-ESI-MS). ELISA detected the presence of sulphonamides in all samples of bovine liver (2.10-77.51 µg/kg), pork muscle (2.84-18.90 µg/kg) and liver (8.41-86.03 µg/kg), chicken liver (2.54-7.18 µg/kg) and kidney (4.35-5.60 µg/kg), 90% bovine muscle (2.52-30.04 µg/kg), 83% pork kidney (2.51-31.89 µg/kg) and 89% chicken muscle (1.78-157.32 µg/kg). The majority of tetracyclines (50%) was detected in pork kidneys (3.88-6.99 µg/kg) and subsequently in chicken muscle (11%) and liver (11%). Aminoglycosides were detected in 50% of chicken kidney (53.44 µg/kg), in 30% of bovine muscle (135.62-239.47 µg/kg), in 17% of pork kidney (151.71 µg/kg) and in 17% of bovine liver (92.47 µg/kg). Fluoroquinolones were detected in all chicken kidney samples (11.96-14.92 µg/kg), 50% of the pork kidney (91.74-255.35 µg/kg), 44% of the chicken muscle (12.76-327.60 µg/kg), 33% of the chicken liver (10.42-31.20 µg/kg) and 20% of the bovine muscle (22.36-79.20 µg/kg).
Using LC-ESI-MS, sulfamethoxazole, an antibiotic belonging to sulfonamides family, was detected in 89% of chicken muscle samples and in 40% of bovine muscle samples with average concentration 8.23 µg/kg (4.51-22.60 µg/kg) and 22.42 µg/kg (4.40-66.95 µg/kg), respectively. Positive for oxytetracycline (tetracyclines antibiotics family), were all pork liver, chicken kidney and liver samples and also in 83% of bovine liver samples. Respectively, the average concentration was 34.80 µg/kg (24.10-45.50 µg/kg), 10.38 µg/kg (5.46-16.69 µg/kg), 59.21 µg/kg (18.59-149.69 µg/kg and 84.31 µg/kg (66.60-110.63 µg/kg). In addition, doxycycline (tetracyclines antibiotics family) was found in 50% of pork liver and kidney samples and 30% of pork muscle samples, with average concentration 26.98 µg/kg, 169.57 µg/kg (12.39-314.60 µg/kg) and 28.47 µg/kg (12.84-44.10 µg/kg), respectively. In regard with fluoroquinolones, enrofloxacin was detected in all chicken kidney samples with average concentration 2.10 μg/kg (1.43-2.77 μg/kg) and marbofloxacin in all pork kidney samples with average concentration 0.86 μg/kg (0.72-1.33 μg/kg).
Using ELISA, it was observed that a sample of chicken muscle (157.32 µg/kg) exceeded acceptable European Residue Limits for sulfonamides (Maximum Residue Levels, MRL’s-Commission Regulation (EU) no 37/2010). For fluoroquinolones, one sample of pork kidney (255.35 µg/kg) and one of chicken muscle (327.60 µg/kg) presented concentrations above the MRLs.
High frequency of positive samples was observed for oxytetracycline by LC-ESI-MS. However, the concentrations of doxycycline were higher. The present research is the first to address the determination of sulphonamides, tetracyclines, aminoglycosides and fluoroquinolones in these meat species by one immunochemical and one chromatographic method.
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