Department of Clinical Medicine, College of Veterinary Medicine, China Agricultural University, Beijing, China.
Mycopathologia. 2013 Apr;175(3-4):241-8. doi: 10.1007/s11046-013-9628-1. Epub 2013 Mar 6.
The aim of this study was to establish a murine protothecal mastitis model and to evaluate the treatment efficiency of gentamicin. Challenge routes were determined with a pathogenic Prototheca zopfii genotype 2 (P. zopfii) strain. 25 BALB/c mice were inoculated in mammary glands with graded dosages (10(3), 10(4), 10(5), 10(6), 10(7) CFU of P. zopfii) and killed on the 7th day. Another 25 animals were also killed at 1, 3, 5, 7, and 9 days after inoculation of 1 × 10(6) CFU of P. zopfii, the milk somatic cell counts, pathological section of mammary glands, and P. zopfii burden were observed. The antimicrobial activity was tested using disc diffusion test and minimum inhibitory concentrations. Gentamicin was given intramuscularly to analyze the therapeutic effect. The results showed that the best infection route was intra-mammary gland, and the mastitis model was established with 1 × 10(6) CFU of P. zopfii. After infection, the somatic cell counts increased significantly. The pathological reaction mainly consisted of infiltration of inflammatory cells, destruction of acini, accumulation of lymphocyte cells and the severity of the changes was dosage and time-dependent. The P. zopfii burden revealed that P. zopfii continuously replicated. In vitro susceptibility tests indicated that the Prototheca strains were antimicrobial susceptible to gentamicin at concentrations between 0.03 and 4 μg/ml. In vivo therapeutic assay demonstrated that high concentrations of gentamicin (≥20 mg/kg) could inhibit the growth of P. zopfii. We conclude that the murine model of protothecal mastitis was established successfully and gentamicin may be an effective choice for treatment of P. zopfii.
本研究旨在建立一种鼠类原壁菌乳腺炎模型，并评估庆大霉素的治疗效果。采用致病性原壁菌 2 型（P. zopfii）菌株确定了挑战途径。将 25 只 BALB/c 小鼠以不同剂量（P. zopfii 的 10(3)、10(4)、10(5)、10(6)、10(7)CFU）接种于乳腺，并于第 7 天处死。另外 25 只动物在接种 1 × 10(6)CFU P. zopfii 后 1、3、5、7 和 9 天也被处死，观察牛奶体细胞计数、乳腺病理切片和 P. zopfii 负荷。采用纸片扩散试验和最小抑菌浓度法检测抗菌活性。肌肉注射庆大霉素分析治疗效果。结果表明，最佳感染途径是乳腺内，用 1 × 10(6)CFU P. zopfii 建立乳腺炎模型。感染后，体细胞计数显著增加。病理反应主要包括炎症细胞浸润、腺泡破坏、淋巴细胞聚集，变化的严重程度与剂量和时间有关。P. zopfii 负荷表明 P. zopfii 不断复制。体外药敏试验表明，原壁菌对浓度在 0.03 至 4 μg/ml 之间的庆大霉素具有抗菌敏感性。体内治疗试验表明，高浓度的庆大霉素（≥20mg/kg）可抑制 P. zopfii 的生长。我们得出结论，成功建立了鼠类原壁菌乳腺炎模型，庆大霉素可能是治疗 P. zopfii 的有效选择。
