Development of antibiotic selection kit towards veterinary applications using glycine passivated magnetic particles

Glycine functionalized (Gly/Fe3O4) and non-functionalized (Fe3O4) magnetic particles were synthesized in an autoclave and characterized by transmission electron microscopy (TEM), Fourier transformed infrared spectroscopy (FTIR), vibrating sample magnetometer (VSM), energy-dispersive X-ray spectroscopy (EDX), differential scanning calorimetry (DSC), X-ray diffraction patterns (XRD) and zeta potential. The size of the both these particles were in the range of 220-230 nm but the shape of the Gly/Fe3O4 particles was hexagonal in contrast to the spherical shape of Fe3O4 particles. The particle characterization tests confirmed that glycine was functionalized on the Gly/Fe3O4 particles, they were positively charged and possessed strong magnetic property. These particles possessed the ability to bind to bacteria such as Escherichia coli, Streptococcus and Staphylococcus in the range of 72-90%. They were used to entrap bacteria from clinical mastitic milk samples from cows. The entrapped bacteria of the above species from these samples were isolated and used individually in the conventional disc-diffusion method of antibiotic susceptibility determination. The results were compared with that of the bacterial species isolated directly from the mastitic milk samples and were found to be 100% concordant (n=25). The developed portable antibiotic selection kit was tested with twenty five samples of mastitic milk. The results indicated that, antibiotic resistant bacteria turned the methylene blue in to white color while the bacteria that were killed (sensitive) retained the blue color of the dye. Thus the right choice of the antibiotic to treat cows with mastitis could be determined based on the naked eye. In conclusion, the kit gave quicker results, was easy to assay and read and can be 'farm-gate' applicable than the presently available conventional method.