Serotypes and antibiotic resistance of 258 isolates of E. rhusiopathiae from slaughter pigs affected with chronic swine erysipelas during a period from 1980 to 1982 in Japan were determined. Predominant serotypes of 213 isolates from the cases of arthritis or lymphadenitis were serotypes 1a, 1b, 2, 6, and 11 (12.2, 7.5, 71.4, 3.3, and 2.3%, respectively). The other serotypes 3, 5, 8, 21, and type N composed 3.3% of isolates. Of 30 isolates from the cases of endocarditis, 3 belonged to serotype 1a, 2 belonged serotype 1b and 25 belonged to serotype 2. Of 15 isolates from the cases of urticaria, 14 belonged to serotype 2 and 1 to Serotype 5.
　A total of 111 (43.0%) strains were resistant to EM, OM, OTC, or DSM. Strains resistant only to OTC (25.6 %) were most frequent, followed by those resistant to OTC and DSM (10.8%), EM, OM, OTC, and DSM (4.6%), EM, OTC, and DSM (1.2%), OM, OTC, and DSM (0.4%), and DSM (0.4%). Of the 111 resistant strains, 104 (93.7%) belonged to serotype 2. Plasmid DNAs were not detected in strains showing the various resistance patterns. This is the first report of resistance of E. rhusipathiae to these antibiotics.