BACTERIOLOGICAL STUDIES ON STREPTOCOCCI FROM BOVINE UDDER I. : SEROLOGICAL AND BIOCHEMICAL OBSERVATIONS ON GROUP-B STREPTOCOCCI AND A GENERAL DESCRIPTION OF STREPTOCOCCI FROM BOVINE MILK IN HOKKAIDO

Abstract

Bacteriological studies on streptococci, especially on Str. agalactiae isolated from bovine milk in Hokkaido during 1955 and 1956 were described. The data obtained are summarized as follows : 1. A total 3508 quarter milk samples derived from 886 cows were examined from the view point of a study of streptococci. Incidence of streptococci in bovine milk in Hokkaido was 27.0% in cows (239 out of 886), and 11.9% in quarters (418 quarters out of 3508). 2. These streptococci were demonstrated from average 69.2% of mastitis quarters and 51.4% of quarters which secreted the abnormal milk, though it was demonstrated from normal milk in 18.8%. These percentages are widely diverse by farms. 3. Isolated strains of streptococci to the number of 319 were divided into Str. agalactiae ; 126 (39.5%), Str. uberis ; 80 (25.1%), Str. bovis ; 34 (10.7%), Str. faecalis ; 17 (5.3%), Str. lactis ; 12 (3.8%), Str. dysgalactiae ; 8 (2.5%), Str. acidominimus ; 5 (1.6%), Str. pyogenes ; 4 (1.3%) and others. 4. Eighty percent of Str. agalactiae and Str. dysgalactiae strain, 70% of Str. uberis strain and about 90% of Str. lactis strain were derived from mastitis or abnormal milk. Contrary to this, more than 50% of Str. bovis or Str. faecalis were isolated from normal milk. 5. One hundred forty-five strains which reacted with group-B serum were serologically typed into type II ; 114 (78.6%) and type III ; 1 (0.7%) by precipitation reaction following LANCEFIELD. The author could not demonstrate any type specific carbohydrate antigens in the remaining 30 strains (20.7%) examined. 6. Some experiments were performed by agar gel diffusion method on the strains lacking type specific carbohydrate. Discussion was offered. 7. Survey on the distributions of these sero-types among cows in 4 farms showed interesting results characteristic to each farm. 8. Biochemical properties, especially sugar fermentation reaction were examined. According to this there seem to be 3 types ; the salicin-negative- and trehalose-positive type, the salicin-positive and trehalose-negative type and the both-positive type. One biochemical type of Str. agalactiae tends to be detected in 1 farm. 9. Str. agalactiae produce acid from galactose, mannose, levulose, sucrose but not from xylose, rhamnose amygdalin, raffinose, inulin, sorbitol and mannitol without exception. With the characters of hydrolysis of sodium hippurate, non-splitting of esculin and production of ammonia from arginine, these fermentation reactions seem to be invariable by strain. 10. The strains which manifested the above mentioned biochemical characters all reacted promptly strong positive with group-B sera by precipitation