Table 2. Serotype distribution across Streptococcus suis strains isolated from pig tonsils.

	Serotype distribution (N = 317)
Serotype	No. of strains	%
2	45	14.2
9,31,32@	38	12
3	27	8.5
21	20	6.3
7	17	5.4
16	12	3.8
4	10	3.2
Other*	65	20.5
Other, double serotypes**	29	9.2
Other, triple serotypes**	9	2.8
Untypeable#	45	14.2

@ Serotyping was repeated three times; additional analysis of 7 representative strains by MLST and 16S rDNA sequencing confirmed that these strains are S. suis.

*Includes serotype 5, 8, 9,10, 11, 12, 13, 15, 19, 20, 22, 23, 25, 26, 27, 28, 29, 30, 31, 33.

**Strains reacting with antisera against two or three different serotypes.

#23 strains were auto-agglutinating, 16 strains could not be assigned to any serotype after agglutination with polyvalent antisera, and 6 strains reacted negatively with all poly-valent antisera.