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 Southern Brazil were classified according to their capsular type. All the isolates were tested for toxin production by using the guinea pig skin test and the Vero cell cytotoxic assay. Most isolates (101) were recovered from piglets with atrophic rhinitis. Of these, 31 belonged to capsular type A, 67 belonged to capsular type D and the remaining three isolates were not classified into the A, B, D or EP. multocida capsular types. Thirteen isolates of which nine were type A, two were type D and two were non-tipable, were recovered from pneumonic lungs of weaned piglets. Two other non-typable isolates were recovered from the subcutaneous tissue of a septicaemic piglet and from the joint of an arthritic 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. Except for the two type A toxigenic isolates there was an agreement between the guinea pig skin test and the Vero cell assay.