Isolation of Streptococcus suis from diseased pigs in Canada

A total of 260 isolates of streptococci collected over a 9-year period from diseased pigs submitted for necropsy were studied. Seventy-seven percent of isolates were identified as S. suis and 32% of S. suis isolates were retrieved in pure culture. S. suis was found more frequently in lungs and was often isolated in conjunction with Actinobacillus pleuropneumoniae, Pasteurella multocida, Escherichia coli and other microorganisms. A total of 151 (76%) of S. suis isolates could be serotyped within the 9 recognized serotypes. Serotype 2 was the most prevalent with 33%, followed by serotypes 3, 5 and 7. All isolates were sensitive to ampicillin, penicillin, cephradine, chloramphenicol and trimethoprim-sulfamethoxazole. Resistance to streptomycin, neomycin and tetracycline appeared to be very high.