Morin D E, Constable P D
Department of Veterinary Clinical Medicine, College of Veterinary Medicine, University of Illinois, Urbana 61802, USA.
J Am Vet Med Assoc. 1998 Sep 15;213(6):855-61.
To use clinical and lactational characteristics to determine whether bacteriologically negative (BN) clinical mastitis episodes are more apt to be caused by gram-negative or gram-positive bacteria, and to investigate severity of clinical mastitis caused by Corynebacterium spp (COR).
Case series.
300 clinical mastitis episodes affecting 123 dairy cows vaccinated against lipopolysaccharide core antigens.
Cows were examined at onset of clinical mastitis, and 23 characteristics, including rectal temperature, heart rate, rumen contraction rate, degree of dehydration, udder and milk characteristics, lactation number, stage of lactation, and season of year, were recorded. Milk production and milk constituent concentrations before onset of mastitis were obtained from herd records. Values for cows with BN milk were compared with values for cows from which milk yielded gram-negative bacteria (GNB) or gram-positive cocci (GPC); logistic regression was used to predict which pathogen type was causing BN mastitis. Characteristics for cows from which milk yielded COR were compared with those of cows from which milk was BN or yielded GPC.
BN clinical mastitis episodes differed significantly from episodes caused by GPC, and were similar to, but milder than, episodes caused by GNB. COR were isolated in a substantial proportion of mastitis episodes, but clinical signs were milder than when GPC were isolated.
Most BN mastitis episodes in cows receiving lipopolysaccharide core antigen vaccines appear to be caused by low-grade infection with GNB, and treatment and management decisions should be made accordingly. The COR may be economically important clinical mastitis pathogens in some herds.
利用临床和泌乳特征来确定细菌学阴性（BN）的临床乳腺炎病例是否更易由革兰氏阴性菌或革兰氏阳性菌引起，并调查棒状杆菌属（COR）所致临床乳腺炎的严重程度。
病例系列研究。
300例临床乳腺炎病例，涉及123头接种脂多糖核心抗原疫苗的奶牛。
在临床乳腺炎发病时对奶牛进行检查，并记录23项特征，包括直肠温度、心率、瘤胃收缩率、脱水程度、乳房和乳汁特征、泌乳次数、泌乳阶段和年份季节。乳腺炎发病前的产奶量和乳汁成分浓度从牛群记录中获取。将BN乳汁奶牛的值与乳汁培养出革兰氏阴性菌（GNB）或革兰氏阳性球菌（GPC）的奶牛的值进行比较；采用逻辑回归来预测导致BN乳腺炎的病原体类型。将乳汁培养出COR的奶牛的特征与乳汁为BN或培养出GPC的奶牛的特征进行比较。
BN临床乳腺炎病例与GPC所致病例有显著差异，与GNB所致病例相似但症状较轻。在相当比例的乳腺炎病例中分离出COR，但临床症状比分离出GPC时轻。
接受脂多糖核心抗原疫苗的奶牛中，大多数BN乳腺炎病例似乎是由GNB的轻度感染引起的，应据此做出治疗和管理决策。在某些牛群中，COR可能是具有经济重要性的临床乳腺炎病原体。
