White M E, Montgomery M E
Can J Vet Res. 1987 Apr;51(2):181-4.
The clinical attributes of 40 dairy cows which had mastitis but no growth of bacteria from the milk were analyzed and compared to the attributes in 102 cows with only gram-positive and 61 cows with only gram-negative bacteria cultured from the milk. Cows with no bacteria cultured from the milk did not differ significantly from cows with gram-positive bacteria cultured, but 9 of 12 attributes were significantly different between cows with no bacteria cultured and cows with gram-negative bacteria cultured. Discriminant analysis was used to classify cows as members of the gram-positive or gram-negative culture groups. The discriminant equation was then applied to the cows with no bacteria cultured, and 78% of cows with no bacteria cultured were classified as members of the gram-positive group. Most mastitis in cows with no bacteria grown from the milk was probably due to gram-positive bacteria. If antibiotic therapy is used in cows with persistent mastitis and a negative culture in the belief that the culture is a false negative, treatment with antibiotics effective only against gram-negative organisms would not be appropriate.
对40头患有乳腺炎但乳汁中未培养出细菌的奶牛的临床特征进行了分析，并与102头乳汁中仅培养出革兰氏阳性菌的奶牛以及61头乳汁中仅培养出革兰氏阴性菌的奶牛的特征进行了比较。乳汁中未培养出细菌的奶牛与培养出革兰氏阳性菌的奶牛之间没有显著差异，但在未培养出细菌的奶牛和培养出革兰氏阴性菌的奶牛之间，12项特征中有9项存在显著差异。采用判别分析将奶牛分类为革兰氏阳性或革兰氏阴性培养组的成员。然后将判别方程应用于乳汁中未培养出细菌的奶牛，78%乳汁中未培养出细菌的奶牛被分类为革兰氏阳性组的成员。乳汁中未培养出细菌的奶牛发生的大多数乳腺炎可能是由革兰氏阳性菌引起的。如果对患有持续性乳腺炎且培养结果为阴性的奶牛使用抗生素治疗，认为培养结果为假阴性，那么使用仅对革兰氏阴性菌有效的抗生素进行治疗是不合适的。
