Cutaneous infections due to Corynebacterium diphtheriae

Toxigenic Corynebacterium diphtheriae was grown from skin lesions of 44 indigent patients seen at the emergency or out-patient departments of this hospital, 43 of them within the last 16 months of the study period. In all cases staphylococci or hemolytic streptococci were also present in the wounds. An increase in the incidence of clinical diphtheria occurred in the few months preceding and overlapping the period of recognition of the cutaneous infections. The gravis strains, which accounted for the majority of the infections, were sensitive to erythromycin and to penicillin, but were relatively resistant to cloxacillin.     

Adhesion of Corynebacterium diphtheriae

The conditions for the direct hemagglutination test performed to determine the degree of adhesion of C. diphtheriae were defined. For this test sheep red blood cells, trypsin-treated ex tempore, were used. Only newly isolated cultures, subcultured for not more than 2-5 times and stored for not more than 2-7 days or freeze-dried, were employed. The culture to be tested was grown in nutrient agar with 10% of normal horse serum. The test was made in microtitrator round-bottom wells. The mixture of different dilutions of the culture was incubated for 2 hours at 37 degrees C, then left overnight at 4 degrees C. All 147 newly isolated or freeze-dried C. diphtheriae strains under test had different degrees of adhesion. Their adhesive activity was unrelated to their biovar. Toxigenic strains were significantly more active in hemagglutination (53.5 +/- 3.0%) than nontoxigenic ones (23.5 +/- 3.9%). The strains isolated from the nose, irrespective of their biological properties, were more active than those isolated from the pharynx.     

Neuraminidase of Corynebacterium diphtheriae

Neuraminidase activity has been found in a variety of strains of Corynebacterium diphtheriae, both toxinogenic and nontoxinogenic. The enzyme has been shown to be intracellular, possibly associated with the cytoplasmic membrane. Toxinogenic strains of the diphtheria bacillus, grown under conditions unsuitable for maximal toxin production, produce neuraminidase, and the enzyme has been purified from cells of the Park Williams no. 8 strain grown under such conditions. Diphtherial toxin and diphtherial neuraminidase have similar molecular weights and remain associated during column chromatography; immunochemically, and in their electrophoretic behavior, they appear distinct.     

Pathogenic properties of Corynebacterium diphtheriae

The main pathogenic properties of 73 C. diphtheriae strains (their adhesive, invasive and cytotoxic activity) were characterized in the cultures of cells HEp-2 and Vero. The quantitative determination of the toxigenicity of 381 strains in the indirect hemagglutination test was made, and the strains were distributed by the degree of their toxigenicity. The characteristics of C. diphtheriae obtained with the use of in vitro experimental models, coincided with the severity of clinical manifestations of the diphtheria in humans, which made it possible to regard the models used in this study as adequate. On the basis of the chosen criteria the characterized strains could be subdivided into highly, moderately and low virulent and the degree of their potential epidemic danger could be determined.     

Corynebacterium diphtheriae: a PTS view to the genome

We have surveyed the publicly available genome sequence of Corynebacterium diphtheriae (www.sanger.ac.uk) to identify components of the phosphotransferase system (PTS), which plays a central role in carbon metabolism in many bacteria. Three gene loci were found to contain putative pts genes. These comprise: (i) the genes of the general phosphotransferases enzyme I (ptsI) and HPr (ptsH), a fructose-specific enzyme IIABC permease (fruA), and a fructose 1-phosphate kinase (fruK); (ii) a gene that encodes an enzyme IIAB of the fructose/mannitol family, and a novel HPr-like gene, ptsF, that encodes an HPr domain fused to a domain of unknown function; (iii) and a gene for a glucose-specific enzyme IIBCA (ptsG). A search for genes that may be putative PTS-targets or that may operate in general carbon regulation revealed a possible regulatory gene encoding an antiterminator protein downstream from ptsG. Furthermore, genes were detected encoding glycerol kinase, glucose kinase, and a homologue of the global activator of carbon catabolite repression in Escherichia coli, CAP. The possible significance of these observations in carbon metabolism and the novel features of the detected genes are discussed.