Chapman H D
Parasitology. 1978 Apr;76(2):177-83. doi: 10.1017/s0031182000047752.
The development of resistance by the Houghton strain of Eimeria tenella to the anticoccidial drugs amprolium, clopidol and methyl benzoquate has been studied. Resistance to amprolium and clopidol developed more readily in experiments where a large number of coccidia were exposed to the drug, either by increasing the number of oocysts in the inoculum or by increasing the number of birds in the group. When 45 birds were given 2.0 X 10(6) oocysts, resistance to amprolium and clopidol appeared after 6 and 7 passages respectively. In previous experiments, under similar conditions, resistance to robenidine developed after 6 passages, suggesting little difference between these three drugs. Resistance to amprolium and clopidol arose gradually as the concentration of drug was increased, but resistance to methyl benzoquate appeared in a single step from sensitivity to high-level resistance. Both amprolium and clopidol-resistant lines showed an 8-fold reduction in drug sensitivity. Attempts to measure the degree of resistance by calculation of the ED50 were unsuccessful.
已对柔嫩艾美耳球虫霍顿株对抗球虫药氨丙啉、氯羟吡啶和甲基苄喹啉的耐药性发展情况进行了研究。在实验中，通过增加接种物中卵囊的数量或增加组内鸟类的数量，使大量球虫接触药物，氨丙啉和氯羟吡啶的耐药性更容易产生。当给45只鸟接种2.0×10⁶个卵囊时，对氨丙啉和氯羟吡啶的耐药性分别在传代6次和7次后出现。在之前的实验中，在类似条件下，对罗布尼丁的耐药性在传代6次后出现，表明这三种药物之间差异不大。随着药物浓度的增加，对氨丙啉和氯羟吡啶的耐药性逐渐产生，但对甲基苄喹啉的耐药性从敏感到高水平耐药是一步出现的。氨丙啉和氯羟吡啶耐药株的药物敏感性均降低了8倍。通过计算半数有效剂量（ED50）来测定耐药程度的尝试未成功。
