Miller B L, Wyatt R D
Avian Dis. 1986 Jul-Sep;30(3):574-9.
Bacillus cereus was used as the assay organism for the quantification of chlortetracycline (CTC) in avian plasma. Antibiotic medium #8 gave significantly larger zones of inhibition than nutrient agar 1.5% when used as the assay medium (P less than or equal to 0.05). When the CTC concentration was measured in serum, citrated plasma, heparinized plasma, and oxalated plasma, no significant differences were found between the inhibition zone diameters produced on antibiotic medium #8. However, there was a significant decrease in the zone diameters produced on this medium when citrated whole blood, oxalated whole blood, and heparinized whole blood were used instead of plasma. The length of incubation of assay plates was inversely related to the inhibition zone diameter, with an incubation time of 8 hr giving the largest and most distinct zones. Storing prepared assay plates at 4 C for 24 hr before use appeared to decrease the variability of the inhibition zone diameters. Storage of citrated plasma at 4 C for 48 hr and at -60 C for 9 days resulted in no significant decreases in CTC concentrations.
蜡样芽孢杆菌被用作测定禽血浆中金霉素（CTC）含量的试验生物。当用作试验培养基时，抗生素培养基#8产生的抑菌圈明显大于1.5%营养琼脂产生的抑菌圈（P≤0.05）。当在血清、枸橼酸化血浆、肝素化血浆和草酸盐血浆中测定CTC浓度时，在抗生素培养基#8上产生的抑菌圈直径之间未发现显著差异。然而，当使用枸橼酸化全血、草酸盐全血和肝素化全血代替血浆时，在该培养基上产生的抑菌圈直径显著减小。试验平板的孵育时间与抑菌圈直径呈负相关，孵育8小时产生的抑菌圈最大且最清晰。使用前将制备好的试验平板在4℃下储存24小时似乎可降低抑菌圈直径的变异性。将枸橼酸化血浆在4℃下储存48小时和在-60℃下储存9天，CTC浓度均未显著降低。
