1988～1990年にみられた<I>Streptococcus suis</I>感染症の発生状況と分離菌株の性状

Abstract

Outbreaks of porcine Streptococcus suis infection occurred in Shizuoka Prefecture during the 1988 to 1990 period, and serotype, virulence against BALB/c mice and drug susceptibility of isolates were examined. Eighteen cases of the infection were observed during this period. All of the cases in 1988 were of meningitis. In 1989, both polyserositis and meningitis were identified and in 1990, cases included pneumonia, septicemia, endocarditis and meningitis. Cases of meningitis, pneumonia, septicemia and endocarditis were found in fattening pigs, whereas polyserositis was observed in suckling pigs. Twenty-seven of 36 isolates of S. suis belonged to serovar 2, and the remaining nine isolates were serovar 1 and 4. Twenty-four BALB/c mice were inoculated intraperitoneally with six isolates of S. suis from various lesions. Isolates from septicemia and leptomeningitis lesions were virulent, while those from serositis and pneumonia were less virulent. The isolates from the nasal cavities and tonsils of clinically healthy pigs had no virulence against mice. The 25 isolates from pathological lesions were highly susceptible to penicillins (PCG and ABPC), but less susceptible to KM and SM. The 14 isolates were resistant to CTC, OTC and TS.