PREVALENCE OF SERPULINA SPECIES IN RELATION TO DIARRHEA AND FEED MEDICATION IN PIG-REARING HERDS IN SWEDEN

Objective-To determine prevalence oi various pheno- and genotypes of S erpulina sp in young pigs in relation to diarrhea and feed medication in Swedish pig-rearing herds. Design-Isolation of spirochetes. Phenoty pical and genotypical classification. Sample Population-Young pigs (n = 358) in 19 pig-rearing herds. Procedure-Serpulina isolates were clas sified according a biochemical scheme based on hemolysis, indole produ ction, hippurate hydrolysis, and alpha-galactosidase, alpha-glucosidas e, and beta-glucosidase activities. The 16S rRNA sequences for 10 of t he field strains and 2 type strains of Serpuiina spp were aligned and compared. Minimum inhibitory concentrations of olaquindox for 9 of the strains were determined. Results-Weakly beta-hemolytic intestinal spi rochetes (WBHIS) were isolated from 17 of the herds and 65% of the sam ples. 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-posit ive WBHIS were isolated in 6 of 7 herds affected by diarrhea, but in o nly 1 of 8 herds without diarrhea. Hippurate-positive strains were clo sely related to the pathogenic strain P43 if judged from sequence comp arisons. Strains with he same biochemical profile isolated within a he rd had identical sequences, but when isolated from different herds, se quence differences were observed. The prevalence of WBHIS was reduced in herds medicated with olaquindox. investigated field strains had min imum inhibitory concentration values less than or equal to 1 mu g/ml f or olaquindox. Conclusion-The presence of WBHIS, with the ability to h ydrolyze hippurate, was related to diarrhea in pig herds. Clinical Rel evance-Potentially pathogenic WBHIS can be distinguished from nonpatho genic strains by the hippurate hydrolysis test.