Mannheimia haemolytica pleuropneumonia in goats associated with shipping stress

ABSTRACT: This study described the epidemiological, clinical, pathological and bacteriological aspects of Mannheimia haemolytica pleuropneumonia in goats associated with shipping stress. Forty goats transported from the Northeast to the Southern region of Brazil died during shipment, or 2-3 days after unloading. Clinical signs included dyspnea, mucopurulent nasal discharge, and coughing. All goats were necropsied, and multiple tissues were collected for histopathological analysis and involved agent identifications. All lungs showed pulmonary consolidation, predominantly affecting the cranioventral lobes, in addition to the marked fibrinous pleuritis, pleural thickening, and pleural adhesions, that affected 90% of the goats. Histologically, there was fibrino-suppurative pleuropneumonia characterized by a diffuse neutrophilic infiltrate admixed with fibrin. Non-hemolytic [85% (34/40)] and hemolytic [15% (6/40)] species were obtained in bacteriological culture. Fir Mannheimia spp. was reported in 26 isolates and subsequently confirmed as M. haemolytica (99% identity), after amplification and partial sequencing of the 16S rDNA gene. Stress may trigger the development of bacterial pleuropneumonia in goats, and non-hemolytic strains of M. haemolytica may cause this condition in goats with severe immunosuppression.

摘要：本研究阐述了与运输应激（shipping stress）相关的山羊溶血曼海姆菌（Mannheimia haemolytica）胸膜肺炎的流行病学、临床、病理及细菌学特征。本研究中，40只从巴西东北部运往南部的山羊在运输途中或卸车后2至3天内死亡。临床症状表现为呼吸困难、黏液脓性鼻漏及咳嗽。对所有山羊实施剖检，并采集多份组织样本用于组织病理学分析与病原体鉴定。所有受试山羊的肺部均出现肺实变，主要累及颅腹侧肺叶；另有90%的山羊出现显著的纤维素性胸膜炎、胸膜增厚及胸膜粘连。组织病理学观察可见纤维素性化脓性胸膜肺炎，特征为弥漫性中性粒细胞浸润伴纤维素渗出。细菌培养分离得到非溶血性菌株[85%（34/40）]与溶血性菌株[15%（6/40）]。经16S rDNA基因扩增及部分测序后，26株分离株被鉴定为曼海姆菌属，后续确认均为溶血曼海姆菌（Mannheimia haemolytica），序列同源性达99%。研究表明，应激可能诱发山羊细菌性胸膜肺炎，而溶血曼海姆菌的非溶血性菌株可在存在严重免疫抑制的山羊中引发该病症。