Antibacterial Residue Excretion via Urine as an Indicator for Therapeutical Treatment Choice and Farm Waste Treatment

Abstract

Many of the infectious diseases that affect livestock have bacteria as etiological agents. Thus, therapy is based on antimicrobials that leave the animal's tissues mainly via urine, reaching the environment through slurry and waste water. Once there, antimicrobial residues may lead to antibacterial resistance as well as toxicity for plants, animals, or humans. Hence, the objective was to describe the rate of antimicrobial excretion in urine in order to select the most appropriate molecule while reducing harmful effects. Thus, 62 pigs were treated with sulfamethoxypyridazine, oxytetracycline, and enrofloxacin. Urine was collected through the withdrawal period and analysed via LC-MS/MS. Oxytetracycline had the slowest rate of degradation (a half-life time of 4.18 days) and the most extended elimination period in urine (over 2 months), followed by enrofloxacin (a half-life time of 1.48 days, total urine elimination in ca. 3 weeks) and sulfamethoxypyridazine (a half-life time of 0.49 days, total urine elimination in ca. 1 week). Bacterial sensitivity and recommendations for responsible use are limiting when selecting the treatment. Nevertheless, with similar effectiveness, sulfamethoxypyridazine would be the choice, as waste treatment would only need to be implemented for 1 week after treatment. Thus, more in-depth knowledge regarding antibacterial elimination would improve resource management, while protecting animals and consumers' health.

Keywords: LC–MS/MS; antibiotic; excretion; quinolone; sulfonamide; urine.

Figure 1

Occurrence of the concentration of sulfamethoxypyridazine in urine samples obtained from pigs treated with sulfamethoxypyridazine at pre-set intervals within the withdrawal period (when day 0 matches the end of the treatment), determined via liquid chromatography with tandem mass spectrometry (LC-MS/MS). The LoD dotted line represents the detection limit of the analytical technique for sulfamethoxypyridazine.

Figure 2

Occurrence of the concentration of oxytetracycline in urine samples obtained from pigs treated with oxytetracycline at pre-set intervals within the withdrawal period (when day 0 matches the end of the treatment), determined by liquid chromatography with tandem mass spectrometry (LC-MS/MS). The LoD dotted line represents the detection limit of the analytical technique for oxytetracycline.

Figure 3

Occurrence of the concentration of enrofloxacin in urine samples obtained from pigs treated with enrofloxacin at pre-set intervals within the withdrawal period (when day 0 matches the end of the treatment), determined via liquid chromatography with tandem mass spectrometry (LC-MS/MS). The LoD dotted line represents the detection limit of the analytical technique for enrofloxacin.

Figure 4

Relationship among the concentrations of sulfamethoxypyridazine (a), oxytetracycline (b), and enrofloxacin (c) detected in muscle and urine samples. The bisecting dotted line represents the 1:1 correlation if both matrixes contained the same concentration of enrofloxacin.

Figure 5

Comparison between the concentrations and rates of removal found for sulfamethoxypyridazine (), oxytetracycline (), and enrofloxacin () in urine after animal treatment within the withdrawal period. The LoD dotted line represents the detection limit of the analytical technique for sulfamethoxypyridazine, oxytetracycline, and enrofloxacin.