Diminazene aceturate (DA) is commonly used in the treatment of bovine babesiosis caused by Babesia bovis. In this study, we attempted to develop resistance in B. bovis in vitro to DA and clofazimine (CF, a novel antibabesial agent) using short- and long-term drug pressures. In the short term, we found that 6.7 ± 2 (0.54 ± 0.16 μM)-, 12.9 ± 8.6 (1.05 ± 0.7 μM)-, and 14 ± 5.9 (1.14 ± 0.48 μM)-fold increases in the half-maximal inhibitory concentration (IC50) of DA were demonstrated on B. bovis cultivated with 0.04 μM of DA pressure for 4, 8, and 12 days, respectively, as compared to that on parental culture (0.08 ± 0.0065 μM) before drug pressure was initiated. However, in B. bovis cultivated with 0.04 μM of DA pressure after 16 days, the parasites could not tolerate 0.8 μM of DA. In the long term, 7.6 ± 3.5-, 20.5 ± 0.1-, and 26.8 ± 5.5-fold increases in the IC50 of DA were demonstrated on parasites from subcultures at days 8, 3, and 5 post-cultivation, respectively, in a drug-free medium, where these subcultures were obtained from B. bovis cultivated with DA pressure with changing doses for 30, 60, and 90 days, respectively. However, the second and third times, no increase was demonstrated on B. bovis from these subcultures at days 15 and 30 post-cultivation in a drug-free medium. In addition, in B. bovis cultivated with drug pressure after 90 days, the parasites tolerate up to 0.64 μM DA. All findings demonstrated that DA resistance in B. bovis is unstable and lost within 15 days of drug withdrawal. However, treatment with subtherapeutic doses of DA in cattle might result in the development of resistance in B. bovis, which may not even respond to subsequent treatments with high doses of DA. Thus, if the bovine babesiosis caused by B. bovis is unresponsive to DA, treatment with other antibabesial agents might be recommended.

中文翻译：

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在牛肝菌中对醋酸二咪唑乙酸盐的抗性不稳定。

醋酸二米那嗪（DA）通常用于治疗牛牛巴贝斯病引起的牛杆状杆菌病。在这项研究中，我们尝试使用短期和长期药物压力体外培养牛双歧杆菌对DA和氯法齐明（CF，一种新型的抗婴儿药）的耐药性。在短期内，我们发现半最大抑制浓度增加6.7±2（0.54±0.16μM）-，12.9±8.6（1.05±0.7μM）-和14±5.9（1.14±0.48μM）-倍与在开始施加药物压力之前的亲本培养（0.08±0.0065μM）相比，在以0.04μMDA压力培养4、8和12天的牛双歧杆菌中证明了DA（IC50）。但是，在16天后用0.04μMDA压力培养的牛双歧杆菌中，寄生虫不能耐受0.8μMDA。从长远来看，为7.6±3.5-，20.5±0.1-和26.8±5。在无毒培养基中，分别在培养后第8、3和5天来自亚培养的寄生虫证明DA的IC50升高了5倍，其中这些亚培养来自于在DA压力下培养的牛双歧杆菌。分别更改30、60和90天的剂量。但是，在无药物培养基中培养后第15天和第30天，第二次和第三次在这些亚培养物中的牛双歧杆菌均未见增加。此外，在90天后用药物压力培养的牛双歧杆菌中，寄生虫可耐受高达0.64μMDA。所有发现均表明，牛B. bovis的DA耐药性不稳定且在停药后15天内消失。但是，在牛中用亚治疗剂量的DA进行治疗可能会导致牛双歧杆菌产生耐药性，甚至对大剂量DA的后续治疗均无反应。因此，如果由牛双歧杆菌引起的牛乳腺病对DA无反应，则可能建议使用其他抗婴儿药治疗。