Differentiation ofCorynebacterium diphtheriae of theMitis type found in diphtheria and ozaena

Summary The purpose of this study was to find out whether there existed any difference betweenC. diphtheriae typemitis always present in the nasal cavity of ozaena patients (the so-calledC. belfanti) andC. diphtheriae of themitis type found in diphtheria patients or carriers. Studying in details all the morphological, cultural and biochemical properties, a difference was found to exist in the reduction of nitrates. This test was investigated in 55 strains ofC. belfanti and 45 strains of themitis type ofC. diphtheriae. All the strains ofC. belfanti yielded negative results in the reduction of nitrates, while all strains ofC. diphtheriae typemitis reduced nitrates within 24 hours. The value of this observation was shorty discussed.     

Characterization of the starch-degrading enzyme ofCorynebacterium diphtheriae typegravis

An inducible cell-surface-bound starch-degrading enzyme produced byCorynebacterium diphtheriae typegravis in tryptose-sodium chloride-maltose broth was partially purified by diethylaminoethylcellulose (DEAE) column chromatography. The partially purified enzyme had approximately six times the specific activity of the crude enzyme. Forty-five percent of the enzyme was recovered in the partially purified form after DEAE chromatography. A molecular weight for the enzyme of approximately 61 200 was obtained by glycerol density gradient centrifugation. The enzyme was inhibited by mercuric ions,p-chloromercuribenzoate, and iodoacetic acid. It was inhibited slightly by EDTA and 1,10-phenanthroline. The enzyme was not inhibited by mercaptoethanol, dithiothreitol, fluoride, bromide, or chloride ions. Activity was lost after precipitation with ethanol, and after concentration with Lyphogel, Sephadex G-15, or lyophilization, but no activity was lost after precipitation with ammonium sulfate. Calcium ions did not activate the enzyme. Maltose was the best inducer of the enzyme. All the saccharides tested induced the enzyme slightly. No phosphorylase was found associated with the organism. However, a phosphatase and possibly an α-glucosidase were produced by the organism. The properties of the starch-degrading enzyme(s) ofCorynebacterium diphtheriae typegravis resemble those of either an amylase, an α-glucosidase, or both. This investigation was supported by Public Health Service grant A102924-10 from the National Institute of Allergies and Infectious Diseases.     

Identification of Corynebacterium diphtheria biovar belfanti among circulating C. diphtheriae strains in Ukraine

The biochemical test of the reduction of nitrates to nitrites made it possible to identify 5.2% of strains belonging to biovar belfanti among 135 C. diphtheriae strains, initially classified within biovar mitis. Out of 7 identified C. diphtheriae belfanti strains, 2 toxigenic strains were isolated from multiple foci diphtheria. According to the results of the polymerase chain reaction, 1 out of 5 non-toxigenic strains had tox gene. All C. diphtheriae belfanti strains were found to have pronounced capacity for adhesion to sheep and human red blood cells. At the stage of the extinction of diphtheria epidemic the practical identification of C. diphtheriae belfanti strains is necessary, as increased adhesion in combination with toxigenic properties may probably promote for bacteria of this biovar to take the leading role at the period of sporadic morbidity.     

Corynebacterium diphtheriae nontoxigenic strain carrying the gene of diphtheria toxin

Among 828 C. diphtheriae nontoxigenic cultures isolated in different region of Russia in 1994-2002, 114 cultures (13.8%) had the gene of diphtheria toxin (gene tox) and were thus called nontoxigenic tox-carrying (NTTC) strains. All NTTC strains were found to belong to biovar mitis and formed neither normal, nor "defective" diphtheria toxin. The most of NTTC strains (94%) belonged to ribotype "Moskva", not occurring among C. diphtheriae toxigenic strains. The incapacity of NNTC strains of forming diphtheria toxin was caused by mutation: the deletion of one nucleotide which led to the shift of the open reading frame and to the formation of the stop codon. The results of these studies are indicative of the fact that a sufficiently homogeneous and isolated group of C. diphtheriae nontoxigenic strains is spread in Russia. These strains carry the nonexpressing gene of diphtheria toxin and are of no epidemic importance in diphtheria infection.