Moats W A, Buckley S A
U.S. Department of Agriculture, Agricultural Research Service, Beltsville, MD 20705, USA.
J AOAC Int. 1998 Jul-Aug;81(4):709-13.
Ceftiofur, a recently introduced antibiotic of the beta-lactam group, is rapidly converted to both free and protein-bound metabolites when administered by the prescribed procedure, intramuscular injection. Free metabolites retain antimicrobial activity and may be detected by antibiotic-screening tests based on antimicrobial activity. It is thus desirable to distinguish ceftiofur metabolites from other antibiotics. A multiresidue procedure for beta-lactams in milk was adapted for determination of free ceftiofur metabolites by collecting appropriate liquid chromatographic fractions during cleanup. Analysis of tissues from treated animals showed that the principal free metabolite was the desfuroylceftiofurcysteine conjugate.
头孢噻呋是最近引入的β-内酰胺类抗生素，按规定程序肌内注射给药后，会迅速转化为游离型和蛋白结合型代谢物。游离型代谢物保留抗菌活性，可通过基于抗菌活性的抗生素筛选试验检测到。因此，有必要将头孢噻呋代谢物与其他抗生素区分开来。通过在净化过程中收集合适的液相色谱馏分，将牛奶中β-内酰胺类抗生素的多残留检测方法用于游离头孢噻呋代谢物的测定。对经治疗动物的组织分析表明，主要的游离型代谢物是去呋喃甲酰头孢噻呋半胱氨酸共轭物。
