CAPSULAR TYPES AND TOXIN PRODUCTION BY STRAINS OF PASTEURELLA-MULTOCIDA ISOLATED FROM PIGS IN SOUTHERN BRAZIL

A total of 116 Pasteurella multocida isolates from 24 pig herds in Sou thern Brazil were classified according to their capsular type. All the isolates were tested for toxin production by using the guinea pig ski n test and the Vero cell cytotoxic assay. Most isolates (101) were rec overed from piglets with atrophic rhinitis. Of these, 31 belonged to c apsular type A, 67 belonged to capsular type D and the remaining three isolates were not classified into the A, B, D or EP. multocida capsul ar types. Thirteen isolates of which nine were type A, two were type D and two were non-tipable, were recovered from pneumonic lungs of wean ed piglets. Two other non-typable isolates were recovered from the sub cutaneous tissue of a septicaemic piglet and from the joint of an arth ritic pig. Forty-three (62.3%) of the 69 type D and two (5%) of the 40 type A P. multocida isolates were found to be toxigenic by the guinea pig skin test. None of the non-typable isolates were toxigenic. Excep t for the two type A toxigenic isolates there was an agreement between the guinea pig skin test and the Vero cell assay.