ESTUDO SOBRE O CORYNEBACTERIUM DIPHTHERIAE. I - FERMENTAÇÃO DA SACAROSE POR BACILOS DIFTÉRICOS VIRULENTOS ISOLADOS EM SÃO PAULO

Abstract

In a preliminary communication to the 5th International Congress of Microbiology, in 1950, the author reported the occurrence, in a group of 95 strains of undoubtecry virnlent diphtheria baeilli, of 19 strains (20 per cent)which were able to ferment saccharose vigoromsly and promptly. In a subsequent in vestigation, 35 new saccharcse fermenting strains were found among 98 virulent strains isolated (like those of the first group) from clinicai cases of diphtheria in São Paulo, an incidence of 35.7 per cent. The virulence tests wer-e performcd intradermally in rabbits according to Frazer 's technique, which includes a control of the specificity of the positive tests. Controls of the action on saccharose were included, ruling out the possibility of the observed effect being due to the presence of rither other carbohydrates in the basic culture media or of saccharolytie enzymes in the serum incorporated to these media. The poSiiibility of Corynebacterium diphtheriae to ferment saccharose has been denied by many bacteriologists. The fermentation test with this carbohydrate has been therefore used in the biochemical ideptification of Corynebact, in order to differentiate the diphtheria bacillus from C. xerose. Several text-books of bacteriology, in recent editions, admit the possibility of occasional strains of C. diphtheriae attacking that sugar. Since strains exhibiting this property are considered as exceptional, the usual biochemical classification of Coryneba.cter1:a might still be resorted to, leading to an underestimation of the incidence of C. diphtheriac infections in areas where the forementioned strains are rather frequent, as it occnrs in São Paulo.