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Streptococcus R (Streptococcus suis type II) infection in pigs in Japan.
National Institute of Animal Health Quarterly
|January 1, 1983
Summary
An epizootic disease caused by Streptococcus suis type II affected young pigs in Japan. The study identified the pathogen and evaluated drug efficacy, finding ampicillin and thiopeptin most effective.
Area of Science:
- Veterinary Medicine
- Bacteriology
- Epizootiology
Background:
- Epizootic disease outbreaks occurred on 9 pig farms in Shimane Prefecture, Japan, between 1979 and 1982.
- Affected pigs, primarily 35-67 days old, exhibited clinical signs including recumbency, convulsions, anorexia, and paddling.
Purpose of the Study:
- To diagnose the causative agent of the epizootic disease in pigs.
- To determine the prevalence and serological characteristics of the identified pathogen.
- To evaluate the efficacy of various antimicrobial drugs against the isolates.
Main Methods:
- Pathological and bacteriological examinations were performed on 20 affected pigs.
- Biological and serological tests, including the preparation of anti-Streptococcus R, S, and T sera, were used for pathogen identification.
- Minimal inhibitory concentration (MIC) assays were conducted for 18 drugs against 19 isolates.
Main Results:
- The disease was diagnosed as streptococcal meningitis and septicemia, with associated endocarditis and pneumonitis.
- Pathogen isolates were identified as Streptococcus R (Streptococcus suis type II).
- The disease was confirmed in 8 additional prefectures beyond Shimane.
- Ampicillin and thiopeptin demonstrated the lowest minimal inhibitory concentrations against the Streptococcus suis isolates.
Conclusions:
- Streptococcus suis type II was identified as the causative agent of the epizootic disease in Japanese pigs.
- Piglet distribution practices may have contributed to disease spread.
- Ampicillin and thiopeptin are recommended as effective treatments for this infection.