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Detection of Streptococcus suis type 2 in tonsils of slaughtered pigs using improved selective and differential media
Y Kataoka1, C Sugimoto, M Nakazawa
1First Research Division, National Institute of Animal Health, Ibaraki, Japan.
Abstract:
New selective and differential media were devised for the isolation and identification of Streptococcus suis type 2. The selective medium (NNCC) agar) was Todd-Hewitt broth containing 1.5% Bactoagar and 5% defibrinated sheep blood with addition of sodium azide (50 micrograms/ml), nalidixic acid (25 micrograms/ml), colistin (12.5 micrograms/ml) and crystal violet (2 micrograms/ml). The differential medium consisted of heart infusion agar and antiserum specific only for S. suis type 2. In a total of 291 pigs tested by a combination of these media, S. suis type 2 was isolated and confirmed from 40 of them (13.7%).
Insights
New media effectively isolate Streptococcus suis type 2. This method identified the bacterium in 13.7% of pigs tested, aiding in disease control.
Area of Science:
- Veterinary Microbiology
- Bacteriology
- Animal Health
Background:
- Streptococcus suis type 2 is a significant swine pathogen.
- Accurate isolation and identification methods are crucial for disease management.
Purpose of the Study:
- To develop novel selective and differential media for Streptococcus suis type 2.
- To evaluate the efficacy of these new media in isolating the pathogen from pigs.
Main Methods:
- Development of a selective medium (NNCC agar) with specific inhibitory agents.
- Creation of a differential medium utilizing type 2-specific antiserum.
- Testing the combined media on 291 pigs.
Main Results:
- The NNCC selective medium contains Todd-Hewitt broth, Bactoagar, sheep blood, sodium azide, nalidixic acid, colistin, and crystal violet.
- The differential medium uses heart infusion agar and S. suis type 2-specific antiserum.
- Streptococcus suis type 2 was isolated and confirmed in 40 out of 291 pigs (13.7% prevalence).
Conclusions:
- The devised selective and differential media are effective for isolating and identifying Streptococcus suis type 2.
- This method offers a reliable tool for diagnosing S. suis type 2 infections in swine populations.
- Improved diagnostic capabilities can contribute to better control strategies for streptococcal diseases in pigs.