Streptoccal infections in pigs. 2. Serological and biochemical examinations

A total of 2,275 strains of haemolytic streptococci (HS) from 1,338 post mortem examined sucking pigs were studied. The serological examination revealed that 43.9 per cent of the strains belonged to group-C and 33.7 per cent belonged to group-L (Table I). Other serogroups amounted to 8.0 per cent and 13.8 per cent of the strains were non-typable. The distribution of serogroups in relation to different organs is presented in Table II. The fermentation pattern of 115 group-C strains against trehalose, sorbitol and lactose was determined (Table III). All but one of the strains appeared to be S. equisimilis. The ability of 127 group-L strains to ferment lactose, hippurate, sorbitol and glycerol is shown in Table IV. Eleven different fermentation patterns were encountered. An antimicrobial resistance pattern was determined for 69 strains (Table V). All the strains, except one, were sensitive to penicillin and chloramphenicol. Only two strains were sensitive to streptomycin. None of the isolated serogroups or biochemical types could be related to a particular pathological lesion or to a particular herd or group of sows within the herd. By comparing the fermentation patterns of the group-L strains isolated from pigs dead with HS infection with those of previously group-L strains from healthy swine, different predominant patterns were found. Possibilities of using these differences in biochemical reactions in separating pathogenic and saprophytic strains are discussed.