Studies On The Efficacy And Residue Elimination Of Cephalonium Intramammary Infusion For The Treatment Of Bovine Mastitis During The Drying Off Period

Bovine mastitis is a common disease in dairy industry. Cephalonium (CEPL) is the first generation of semi-synthetic cephalosporin, and its’antimicrobial spectrum is widely. Because of its antimicrobial ability against Gram-negative and Gram-positive bacteria, CEPL is used to prevent and treat cattle mastitis infected by bacteria during dry period. This research is based on the efficacy of CEPL treating cow mastitis during dry period and the residue depletion of CEPL in milk, and the result provide a reference of using CEPL in clinical treatment.1. Antibacterial activity of cephalonium to the main pathogenic bacteria from dairy cow mastitisThe MICs of cephalonium, cephapirin, amoxicillin and cloxacillin were determined by microdilution mothed. The result showed that MIC50of cephalonium, cephapirin, amoxicillin and cloxacillin to E. coli were respectively4μg/ml,8μg/ml,8μg/ml and56μg/ml, MIC90were respectively64μg/ml,64μg/ml,>128μg/ml and>128μg/ml; MIC50of these drugs to S. aureus were respectively0.125μg/ml,0.25μg/ml,2μg/ml and1μg/ml, and MIC90were respectively16μg/ml,16μg/ml,32μg/ml and128μg/ml. MIC50of these drugs to S. uberis were respectively MIC504μg/ml,8μg/ml,16μg/ml and128μg/ml, and MIC90were respectively8μg/ml,16μg/ml,64μg/ml,128μg/ml. Streptococcus dysgalactiae MIC508μg/ml,8μg/ml,8μg/ml,128μg/ml, MIC9016μg/ml,8μg/ml,128μg/ml and>128μg/ml. MIC50of these drugs to S. agalactiae were respectively0.25μg/ml,4μg/ml,0.25μg/ml and32μg/ml, and MIC90were respectively4μg/ml,16μg/ml,4μg/ml and>128μg/ml. The tests showed that, cephalonium and cephapirin is highly sensitive to clinical isolated strain of S. aureus, moderately sensitive to Streptococcus.2. The effectiveness of cephalonium intramammary infusion for the treatment of bovine mastitis during the drying off period60healthy dry cows were selected in this research, after the last milking, every mammary area was perfused by CEPL or the control drug. Before dry milk, and1,3,5days after delivery of the cows, SCC and bacteria of milk sample from every udder were examinated. The result shows that CEPL has no difference from the control drug in cure rate, new infection rate and bacteria clearance. Every mammary area of the dry cows is perfused by250mg CEPL, and the method is effective to cure and prevent the subclinical mastitis of the dry cows. CEPL is similar with the control drug in curing mastitis of dry cows.3. Determination of Cephalonium residues in milk by by liquid chromatography-tandem mass spectrometrycephapirin and cephalonium residues in milk by liquid chromatography-tandem mass spectrometry was determinated. It was used to investigate the residue depletion cephapirin benzathine and cephalonium in milk. Cephapirin and cephalonium was quantitatively determined using cephapirin-D4as the internal standard. The drug in milk sample was extracted and deproteined with acetonitrile.The eluent was concentrated to dryness under a stream of nitrogen, and the residue was dissolved in10%methanol solution.Then it was injected into the HPLC-MS/MS system. The regression curves for three kinds of drugs were linear in the range of2.5～100μg/kg, respectively. The LOD was2.5μg/kg, the LOQ was5μg/kg. The recovery rate was more than75%. Inter-day CV was between1.67%-9.68%, intra-day CV was between2.21%～6.62%.4studies on the residue elimination of Cephalonium in milk for Cephalonium intramammary infusion by intramammary infusionFouty healthy Holstein cows during the dry period were used in residue depletion study. Cephalonium was administered by the intramammy route at a dose of250mg/quarter in cows.The results showed the concentrations of CEPL were lower the LOD (2.5μg/kg) of the method established. Meanwhile it was far below the MRL (10μg/kg). According to the usual methods of calculation for the withdrawal period in our country, the withdrawal period for milk of cephalonium was advised as0d in cow.