Abstract
Summary
In Baltimore during the past 3 years the gravis type of diphtheria bacillus has, as heretofore, been absent or rare. However, during this period there have been isolated, chiefly from clinical cases of diphtheria and contacts thereof, but also from casual carriers, many virulent and nonvirulent diphtheria bacilli characterized by (a) the production of minute colonies on blood-agar media containing potassium tellurite, and (b) slow, slight or irregular fermentation of dextrose. These characters are very frequently found together and for such organisms the designation minimus type is suggested as a convenience in discussion. Other virulent strains have been found which regularly ferment saccharose. The saccharose-fermenting strains studied do not appear to differ in other respects from ordinary diphtheria bacilli. A relationship between the minimus type of C. diphtheriae, and recent epidemiological and clinical observations in Baltimore, as well as the possible value of bacterial antigens in addition to routine toxoid in prophylaxis, are discussed. Authors' summary.
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