Epidemiological relationship of human and swine Streptococcus suis isolates

Two cases of meningitis due to Streptococcus suis in humans are reported he re. A butcher and an abattoir worker were referred to a health centre in Ca stellon (Spain) with fever and sym toms of meningitis. After adequate treat ment, a slight Epoacusia persisted as sequelae in both cases. Colonies of S . suis group R, serotype 2 and phenotype MRP+EF+ were isolated from cerebro espinal fluid. Epidemiological studies showed that both workers had in comm on the handling of pork meat of slaughtered healthy pigs from three closed farms. A study of the tonsils from apparently healthy, slaughtered pigs was carried out. A total of 234 tonsillar samples were obtained and 81 strains of S. suis were isolated from them. Serotype 2 appeared to be the most fre quent (50.6 %), and the analysis for phenotype showed a high percentage of tonsillar strains with the phenotype MRP+EF+ (35.9 %). The humans and 28 to nsillar swine strains showed a similar profile (S suis group R, serotype 2 and phenotype MRP+EF+). A total of 26 of the swine isolates were analysed b y ribotyping using EcoRI. The human strains showed the same six-band hybrid ization pattern that shared five bands with the pattern most frequently sho wn by most of the tonsillar S. suis group R, serotype 2 and phenotype MRP+E F+ strains, differing only in the lightest, faintest band which was slightl y less anodical in human (greater than or equal to 1.8 kb) than in swine (a pproximate to 1.8 kb). From these results, both groups of strains, humans a nd porcine, showed differences; how can these differences in the pattern of ribotyping be explained if they should have the same origin? Is it possibl e that they have undergone an adaptation to the new host or perhaps the mod ification is due to other unknown causes? Further studies in this area are required in order to answer these questions.