Screening of quinolone residues from slaughtered bovine urines

Productive pressures have induced livestock and animal husbandries to implement intensive farming systems characterized by high animal densities and increasing infectious diseases that mostly have bacterial origin. Thus, gold standard therapy is represented by antimicrobials that leave the animal tissues via urine, reaching environment through slurry and wastewaters (Serrano et al., 2021). On the other hand, antimicrobials could be administered for non-therapeutic purposes, including disease prophylaxis and growth promotion. This trend has encouraged uncontrolled drugs usage especially in developing countries (Van Boeckel et al 2015). Consequently, residual drugs are often identified from food matrices (i.e., xenobiotic substance persistence in slaughtered animals) and have also induced to the selection of resistant bacterial strains to the most used antibiotic molecules (Ramatla et al., 2017). Hence, the present workobjective was to describe the eventual presence of quinolone residues in order to control antimicrobial residues that may lead to the antimicrobial resistance as well as toxicity for plants, animal and humans. This antibiotic family is commonly used in bovine bacterial disease (Tessa et al., 2016).The survey involved 32 female bovines (mixed-breed) aged from 18 to 24 months from 2 farms located in North-Est of Italy, Veneto region, during 2021. Urine samples were collected from each animal in 2 slaughterhouses. During transportation and storage to the laboratory, all aliquots were individually packed and kept at refrigerated temperature (+4°C). The evaluation of quinolone residual presence was performed by using the liquid chromatography with mass spectrograph (Mieriex NutriSciences Rasena, Treviso, Italy). The screened antibiotics were: nalidixic acid, oxalinic acid, carbadox, cinoxacin, ciprofloxacin, danofloxacin, enoxacin, enrofloxacin, enrofloxacin, ciprofloxacin, flumechin, lomefloxacin, marbofloxacin, norfloxacin, ofloxacin, norfloxacin. Results demonstrated total absence of residual antibiotics. Indeed, as reported by Serrano et al. (2021), the complete excretion of enrofloxacin needs of three weeks and excretion continues for long. It means that quinolone might be removed from animal muscles and it could hide a risk for human health. The 73% of antibiotic global use has been employed in the meat supply chain, and forecasts (regarding drug consumption) predicted a growth of 11.5% by 2030 (Treiber et al., 2021). Quinolone family is identified as a “Critical Important Antimicrobial” by the World Health Organization. Thermal treatments can reduce the risk ingestion of sulfonamides, tetracyclines and fluoroquinolones, but do not guarantee their total dissolution and degradation. Quinolones and beta-lactamases are characterized by high stability to heat processing and, for this reason, represent huge risk to human health. There is no study about detection of quinolone residues in cooked meat, but their residues can persist in milk after pasteurization treatments and reach the dairy industry and the final consumer.Metabolic and catabolic toxic effects need more knowledge and detailed studies. Due to their possible persistence and presence in cooked meat, antibiotic residues should be inserted in maximum daily intake, if limits were established by Legislations. Another important concern is antimicrobial resistance phenomenon that hasn’t physic or geographic limits. EFSA Report in 2019 showed that 31.705 samples were not conform on 1191 analyzed; 0,41% of these came from beef food chain (0,04% in Italy) (EFSA, 2021). Hence, our results are in line with national data.