STUDIES ON BOVINE MASTITIS : IV.ON THE ETIOLOGY OF BOVINE MASTITIS

Abstract

The authors previously rerorted on the bacterial flora of the udders ofhealthy and mastitis cows, as well as on the bacteriological classification of theisolated organisms.I. Comparison of the bacterial flora of the udders of healthy and mastitis cows.As for the normal flora of the udders, (3 herds, 53 cows, 201 quarters)Staphylococcus was the most predominant and Bacillus, Corynebacterium, Stre-ptococcus, Gafkya, Sarcina, Gram-negative bacilli and Fungi were usolated witha lessening frequency in the order listed. Staphylococcus, Streptococcus, Bacillus, Gafkya, Corynebacterium and Gram-negative bacilli were isolated in the stateof either pure culture or predominant to the other organisms at the rate of 42, 9, 6, 5, 4 and 1%, respectively. Two or more kinds of organisms were isolatedin an almost equal quantity in 29% and no viable organisms were isolated in2, 96.As for the bacterial flora of mastitis cows, (100) Streptococcus was isolatedmost frequently and Bacillus, Gram-negative bacilli, Staphylococcus, (:oryne-bacterium, Sarcina, and Gafkya were isolated less frequently in the order listed.Streptococcus, Corynebacterium, Staphylococcus, and Gram-negative bacilli wereisolated in the state of either pure culture or predominant to the other organismsin 51, 11, 9 and 9%, respectively. Two or more kinds of organisms weremsolated in an almost equal amount in I7g and bacterial isolation was negativein 3%.IT. Relation between our classification of the organisms isolated frorn norrnaludders and bovine mastitis.I) StreptococcusLactococcus group was predominant in both the healthy or the diseasedudders next in frequency was Enterococcus group and the least frequent wasSlre ptococcus group.2) StaphylococcusAs for the normal flora of udders, Staphylococcus type II was observedrnost frequently (89%), Staphylococcus type I came next (9, 961), Staphylococcustype III was least in frequency (1%).In the case of rrnastitis, Staphylococcus type I comprised 40% of the organisnxsisolated and Staphylcccccus type II, 60%. Out ofwas Staphylococcus type II and this moreover, was isolated with a considerableamount of Escherichiae.3 ) CorynebacteriumAll the organisms isolated from normal udders were Corynebacteriumpseudodiphthericum, while the organisms isolated from cases of of mastitis, 70%were identified as Corxnebacterium pxoxenes and 30% as Corxnebacterium pseudo-diphthericuwt.In the case of mastitis out of the 11 cases from which ()orynebaeterittmwas isolated in the state of either pure culture or predominant to otherorzanisms, 9 cases were Corxnebacterium pxozenes and 2 cases were Cortne-bacterium pseudodiphthericum, one being mixed with Streptococcus and the otherwith Escherichiae and Streptococcus.4) Gram-negative bacilliA few strains isolated from normal udders were identified as Enterobacter-iaceae, while many strains isolated from the cases of mastitis were identified asEschetichiae.In the case of mastitis, out of the 9 cases from which Gram-negative bacilliwere isolated in the state of either pure culture or predominant to the otherorganisms, 8 cases were Escherichiae and 1 case was Protetts, mixed withStreptococcus.Isolation of Gafkya and Sarcina was low in frequency and Bacillus wasrather high from both normal and mastitis udders. In the case of mastitis, however, these organisms were not isolated in the predominant state.On the basis of the above mentioned results, Streptococcns, especiallyLactococcus nrouv, StaPh;lococcus tvr>e I, Corxnebacterittm P?ozenes and Escheri-chiae are regarded as the most important causative agents of bovine mastitis. [the rest omitted]