Impact of Timing and Dosage of a Fluoroquinolone Treatment on the Microbiological, Pathological, and Clinical Outcomes of Calves Challenged with Mannheimia haemolytica
Impact of Timing and Dosage of a Fluoroquinolone Treatment on the Microbiological, Pathological, and Clinical Outcomes of Calves Challenged with Mannheimia haemolytica
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DOI：
10.3389/fmicb.2016.00237
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发表时间：
2016-03-02
影响因子：
5.2
通讯作者：
Meyer, Gilles
中科院分区：
文献类型：
--
作者：
Lhermie, Guillaume;Ferran, Aude A.;Meyer, Gilles
在感染4.10（7）CFU溶血性曼氏杆菌A1的小牛中，评价了早期和低接种量调整的马波沙星治疗对微生物学和临床结局的有效性。根据攻毒后10 h内的直肠温度升高，纳入22头小牛，并将其分为4组，分别在入选后2-4 h（早期处理，E2）、入选后35-39 h（晚期处理，L2，E10）接受单次肌肉注射生理盐水（CON）、2 mg/kg马波沙星（早期处理，E2）、2 mg/kg马波沙星或10 mg/kg马波沙星。在CON犊牛中，M.支气管肺泡灌洗液中的溶血性DNA载量从纳入到第4天持续增加，并与持续的呼吸道临床体征和肺部病变相关。在早期和晚期治疗时，M.溶血性菌载量范围分别为3.5-4和5.5-6 log（10）DNA拷贝/mL。早期2 mg/kg马波沙星治疗导致所有小牛中的细菌迅速、完全消除。后期处理诱导细菌负荷降低，但6头L2小牛中的3头和6头L10小牛中的1头仍为M阳性。第4天溶血。除CON小牛外，所有动物均在给药后24 h内表现出临床改善。然而，早期2 mg/kg给药对预防肺部病变更有效，如肉眼病变的范围和严重程度降低以及组织病理学评分所示。这些结果首次证明，在疾病早期给予减少抗生素治疗并针对低细菌载量的方案在天然牛肺炎模型中可能有效。
The efficacy of an early and low inoculum-adjusted marbofloxacin treatment was evaluated on microbiological and clinical outcomes in calves infected with 4.10(7) CFU of Mannheimia haemolytica A1. Twenty-two calves were included based on their rectal temperature rise in the 10 h after challenge and allocated in four groups, receiving a single intramuscular injection of saline (CON), 2 mg/kg marbofloxacin 2-4 h after inclusion (early treatment, E2), 2 or 10 mg/kg marbofloxacin 35-39 h after inclusion (late treatments, L2, El 0). In CON calves, M. haemolytica DNA loads in bronchoalveolar lavages continuously increased from inclusion to day 4, and were associated with persistent respiratory clinical signs and lung lesions. At times of early and late treatments, M. haemolytica loads ranged within 3.5-4 and 5.5-6 log(10) DNA copies/mL, respectively. Early 2 mg/kg marbofloxacin treatment led to rapid and total elimination of bacteria in all calves. The late treatments induced a reduction of bacterial loads, but 3 of 6 L2 and 1 of 6 L10 calves were still positive for M. haemolytica at day 4. Except for CON calves, all animals exhibited clinical improvement within 24 h after treatment. However, early 2 mg/kg treatment was more efficacious to prevent pulmonary lesions, as indicated by the reduction of the extension and severity of gross lesions and by the histopathological scores. These results demonstrated for the first time that a reduced antibiotic regimen given at an early stage of the disease and targeting a low bacterial load could be efficacious in a natural bovine model of pneumonia.