The epidemiological studies of Streptococcus suis infections in Japan from 1987 to 1991

The epidemiological studies of S. suis infections in Japan were carried out between 1987 to 1991. A total of 380 S. suis strains isolated from pigs, cattle and a horse were serotyped by using antisera against S. suis types 1 to 22. A total of 318 (83.7%) of S. suis isolates were serologically typable. Serotype 2 was the most prevalent with 28.2%, followed by type 7 (10.8%), 1/2 (8.4%), 3 (7.4%) and 4 (5.5%). Of twenty S. suis strains isolated from cattle, eight were type 9, one was type 10, five were type 18, one was type 20 and five were untypable. One out of all the strains was also isolated from a racing horse with pneumonia. The majority of the isolates were originated from meningitis (38.2%), followed by from pneumonia (33.4%) and endocarditis (9.2%). Of all of the S. suis isolates, 333 isolates (87.6%) were identified correctly by API STREP 20 system.