ABSTRACT
Enterotoxigenicity, virulence and antimicrobial susceptibility were studied in thirteen strains of Yersinia enterocolitica isolated from meat foods and organs of slaughtered animals. The following biotypes (B), serotypes (O) and lisotypes (Lis) were studied: B2, O:9, Lis X3 and B1, O:7,8, Lis Xo (from thick fresh sausages); B1, O:5, Lis Xz (from slender sausages); B1, O:5, Lis Xz and B2, O:9, Lis X3 (from bovine tongues); B1, O:6, Lis Xz (from porcine tongues) and B1, O:6, Lis Xz (from porcine caeca) (Table 1). Virulence was determined by i) the autoagglutination test (Laird and Cavanaugh), replacing in the Eagle medium amino acids and vitamins with proteose peptone (1
) and yeast extract (0.5
), and ii) the calcium dependency test. The LD50 of five strains was determined by i.p. injection of O.5 ml of cell suspensions into white mice and estimated by the Spearman Kõrber method. LD50 varied from 2 x 10(9) to 7 x 10(9) viable cells per ml. The enterotoxigenicity test was carried out in suckling white mice and the invasiveness test (Sereny) in adult white mice. Two strains showed autoagglutination, five calcium dependency, two were invasive and eight produced enterotoxin. Antimicrobial susceptibility was assayed by the modified Kirby and Bauer test. All the strains were susceptible to kanamycin, amikacin, cefotaxime, cefuroxime, chloramphenicol, fosfomycin, mezlocillin, nitrofurantoin, piperacillin, piperimidic acid, polymyxin B, sisomycin and tobramycin, and resistant to cephalotoxin, ampicillin and trimethoprim-sulfamethoxazole.(ABSTRACT TRUNCATED AT 250 WORDS)