Determination and kinetics of enrofloxacin and ciprofloxacin in Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a liquid chromatography/mass spectrometry method

Determination and kinetics of enrofloxacin and ciprofloxacin in Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a liquid chromatography/mass spectrometry method. J. vet. Pharmacol. Therap. 34, 142-152. The fluoroquinolones enrofloxacin (EF) and ciprofloxacin (CF) residues were investigated in the edible tissues of two important Asian aquacultured species such as Tra catfish (Pangasianodon hypophthalmus) and giant freshwater prawn (Macrobrachium rosenbergii) using a sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry method. Fish and prawn were treated with medicated feed with multiple doses of EF, in field conditions. A validation study of the analytical method was realized in terms of linearity, specificity, precision (repeatability and within-laboratory reproducibility), recovery and decision limit (CCα). The time needed before the antibiotic disappears from animal tissues or reach the maximum residue limit (MRL, 100μg/kg) was assessed. The concentration values of EF detected in Tra catfish tissue were between the MRL and 2×MRL concentrations, according to the fish density, 7days following the end of the enrofloxacin treatment (20mg/kg body weight per day, for seven consecutive days). The concentration value of ER in prawn tissue was lower than the MRL and the limit of quantification (LOQ, 14μg/kg) 5 and 7days after the stop of the EF treatment (50mg/kg body weight per day, for five consecutive days), respectively. The mean detected levels of CF was much lower in comparison with that of EF, indicating that only a small part of EF is metabolized into CF (<5%) in both Tra catfish and prawn.     

Furan formation from lipids in starch-based model systems, as influenced by interactions with antioxidants and proteins

The formation of furan upon sterilization of a lipid-containing starch gel was investigated in the presence of various antioxidants, namely, α-tocopherol, β-carotene, and ascorbic acid, with and without proteins. Results indicated that α-tocopherol did not significantly influence furan formation from oxidized lipids. β-Carotene, suggested previously to be a furan precursor itself, did influence the generation of furan in a concentration-dependent manner, although to a limited extent. Surprisingly, the presence of lipids seemed to limit the furan generation from β-carotene. Interestingly, the addition of ascorbic acid to the emulsions containing soybean or sunflower oils considerably enhanced the formation of furan from these oils. This was also the case when fresh oils were applied, shown previously to be nearly unable to generate furan. This observation can be explained by an intensified ascorbic acid degradation stimulated by the presence of lipids.     

The use of antibiotics in cattle in North-East Benin: pharmaceutical inventory and risk practices of cattle breeders

This study’s aim is to inventory antibiotics used in cattle in North-East Benin and assess risk practices that could be the cause of both food chain contamination by antibiotic residues and selection of antibiotic-resistant bacteria in animals and humans. A survey was conducted among 98 cattle breeders in the districts of Banikoara, Kandi, Bembereke, and Kalale in North Benin. Semi-structured interviews were conducted, covering breeder status, breeding system, and antibiotic use. Multiple correspondence analysis and hierarchical classification analysis were conducted to establish a breeder typology. Breeders mainly belonged to the Fulani ethnic group (71.4?±?8.9%) and almost all of them received “no formal education” (96.9?±?3.4%). Cattle herds were mainly composed of a single breed, the Borgou (76.4?±?8.1%) or the Fulani Zebu (16.0?±?7.0%). Some herds were mixed. Antibiotics groups used in cattle breeding were tetracyclines, beta-lactams, sulfonamides, aminoglycosides, and macrolides, used by respectively 100%, 69.4?±?9.1%, 56.1?±?9.8%, 44.9?±?9.8%, and 34.7?±?9.4% of breeders. These drugs were purchased in local markets (59.0?±?15.4%) and veterinary pharmacy (41.0?±?15.4%). They were mainly used against respiratory diseases, lameness, mastitis, omphalitis and neonatal enteritis, and skin diseases. Only 49.0?±?9.9% of breeders seek veterinary services to treat animals and 92.9?±?5.1% of them did not respect antibiotic withdrawal times. These practices suggest that both contamination of bovine meat with antibiotic residues and selection of resistant bacteria are to be expected, resulting in adverse health effects on consumers.

     

Evaluation of antimicrobial products used in tilapia (Oreochromis spp.) and whiteleg shrimp (Litopenaeus vannamei) aquaculture

Despite the importance of aquaculture increases for feeding the growing world population, professional farm management and proper use of aquaculture products or drugs are needed. It is important to know the quality of commercial antimicrobial products on the market while there is wide use of antimicrobials to treat fish diseases. The most commonly used antimicrobial products were identified from a previous survey, included amoxicillin, enrofloxacin, florfenicol, sulphadiazine, sulphamonomethoxine and sulphadimidine. Eight local chemical supply shops were randomly sampled in representative aquaculture areas in Maoming and Zhanjiang districts of south China in 2013. In this study, only eight products contained active substances within ±10% of the concentration declared on the product label among the 30 different most used commercial products; while six products did not contain any of the declared antimicrobials. Three products without labels were sold as ‘pure antimicrobial’ and had high concentrations of active antimicrobials. Furthermore, most products only provided ambiguous information on the packages on both antimicrobial usage and dosage; and only one product stated how to prepare medicated feed which is important for efficient usage. The results of this study showed that the aquaculture antimicrobial products sold on the market were of low quality and thus compromised effective fish disease treatment. Moreover, insufficient information on products’ labels would provide limited instruction on correct antimicrobial usage. Inspection and supervision by both private companies and the government's sector require strengthening.     

Screening of quinalphos,trifluralin and dichlorvos residues in fresh water of aquaculture systems in Mekong Delta,Vietnam

To develop an easy and reliable method for detecting pesticides and their residues in the Mekong Delta, a GC‐MS analytical method was developed and validated according to European guidelines (SANTE/11945/2015) for the determination of residues of three pesticides (quinalphos, trifluralin and dichlorvos) in water. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.002 and 0.007 μg/L, respectively, for quinalphos and trifluralin, and 0.016 and 0.053 μg/L, respectively, for dichlorvos and quinalphos. The repeatability, the within‐laboratory reproducibility as well as the trueness met the European criteria. The recovery rate ranged between 72% (for dichlorvos and quinalphos) and 82% (for trifluralin). The developed method was then applied for the analysis of 33 water samples, collected in April 2013, at the beginning of the rainy season in the Mekong Delta in Vietnam. Thirteen samples were from rice field, 10 were collected from cat fish ponds and from red tilapia cages. Results showed that only 9% of total water samples analysed contained residues of pesticides, but only in water from rice fish systems. From the 13 samples taken in these systems, quinalphos was detected in three samples. The other two pesticides were not detected. A comparison between analytical results obtained from GC‐MS and an alternative method, that is GC‐ECD indicated that GC‐ECD is less sensitive than GC‐MS, with LOQ ranging from 0.37 to 1.18 (depending on the pesticide). However, for samples with concentrations above these LOQ, no significant difference was observed between the results obtained from the two analytical methodologies.