Prevalence of Serpulina species in relation to diarrhea and feed medication in pig-rearing herds in Sweden.

OBJECTIVE

To determine prevalence of various pheno- and genotypes of Serpulina sp in young pigs in relation to diarrhea and feed medication in Swedish pig-rearing herds.

DESIGN

Isolation of spirochetes. Phenotypical and genotypical classification.

SAMPLE POPULATION

Young pigs (n = 358) in 19 pigrearing herds.

PROCEDURE

Serpulina isolates were classified according to a biochemical scheme based on hemolysis, indole production, hippurate hydrolysis, and alpha-galactosidase, alpha-glucosidase, and beta-glucosidase activities. The 16S rRNA sequences for 10 of the field strains and 2 type strains of Serpulina spp were aligned and compared. Minimum inhibitory concentrations of olaquindox for 9 of the strains were determined.

RESULTS

Weakly beta-hemolytic intestinal spirochetes (WBHIS) were isolated from 17 of the herds and 65% of the samples. More than 1 phenotype of WBHIS was found in 12 of the 19 herds. S hyodysenteriae was not isolated in any of the herds. Hippurate-positive WBHIS were isolated in 6 of 7 herds affected by diarrhea, but in only 1 of 8 herds without diarrhea. Hippurate-positive strains were closely related to the pathogenic strain P43 if judged from sequence comparisons. Strains with the same biochemical profile isolated within a herd had identical sequences, but when isolated from different herds, sequence differences were observed. The prevalence of WBHIS was reduced in herds medicated with olaquindox. Investigated field strains had minimum inhibitory concentration values < or = 1 microgram/ml for olaquindox.

CONCLUSION

The presence of WBHIS, with the ability to hydrolyze hippurate, was related to diarrhea in pig herds.

CLINICAL RELEVANCE

Potentially pathogenic WBHIS can be distinguished from nonpathogenic strains by the hippurate hydrolysis test.