D. S. Pérez

DETERMINATION OF ANTIBIOTIC FOSFOMYCIN IN CHICKEN SERUM BY LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY

A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of fosfomycin in chicken serum using fudosteine as the internal standard. Serum samples were treated with methanol to precipitate proteins. A subsequent clean up using liquid-liquid extraction followed by dilution was performed to eliminate phospholipids which are prone to produce unwanted matrix effects. The HPLC-MS/MS system involved the use of an isocratic mobile phase on a cyano stationary phase column and electrospray ion source operating in negative ion mode. Single reaction monitoring of transitions m/z 137 →79 and 178 →91 was performed on a triple quadrupole mass spectrometer to quantify fosfomycin and fudosteine, respectively. Response was linear over the range of 0.1 to 50 μg mL−1. Recovery ranged from 95 to 108%. Accuracy determined for spiked samples at 5, 10, and 20 μg mL−1 was −7.8, 1 and −0.7%, respectively, expressed as relative error. Within day and between days precision, in terms of coefficient of variation, were less than 10% for all concentrations. The developed method was successfully used in a pharmacokinetic study after oral administration of calcium fosfomycin to broiler chickens.

Penetration of Fosfomycin into IPEC-J2 Cells in the Presence or Absence of Deoxynivalenol

Fosfomycin (FOS) is an antibiotic used in pig farms for treatment and prevention of infections caused by resistant bacteria during the post-weaning period. Antibiotics and non-toxic concentrations of mycotoxins, such as deoxynivalenol (DON) are frequently found in the diet of animals. These compounds can establish interactions in the intestinal tract, which could affect and/or modify the penetration of FOS to enterocytes. The aim of this study was to determine the penetration of FOS into IPECJ-2 cells, a cell line derived from the small intestine of piglets, in the presence and absence of DON. The results from this study showed that there was statistically significant difference in the intracellular concentration of FOS between cells incubated with 580 µg/ml FOS and cells incubated with 580 µg/ml FOS and 1 µg/ml DON. The Cmax of the intracellular antibiotic in the culture plates incubated with FOS in absence of DON was 45.81 µg/ml with a tmax of 4 h. When IPEC-2 cells were incubated with FOS and DON the Cmax was 20.06 µg/ml and the tmax was 30 min. It is concluded that the non-toxic concentration of DON on IPEC-J2 cells after short-term exposure, interferes with the pharmacokinetics of the antibiotic.