FATAL RESPIRATORY-TRACT DIPHTHERIA APPARENTLY CAUSED BY NONTOXIGENIC STRAINS OF CORYNEBACTERIUM-DIPHTHERIAE

A major-diphtheria epidemic affecting the whole population of St, Pete rsburg started in 1990. During the period of 1993 to 1995, 4600 patien ts with clinical respiratory tract diphitheria were treated in Botkin' s Hospital, From 112 (2.4%) of these patients only a nontoxigenic stra in of Corynebacterium diphtheriae was isolated, Three patients with th is strain who were suffering from clinical disease consistent with cla ssical toxic diphtheria died. All had myocarditis, two had asphyxia du e to membrane formation in the lower respiratory tract, and one had se vere polyneuritis. In two patients the causative agent was of the biot ype mitis and in the third intermedius, whereas the prevailing epidemi c strain was of the biotype gravis, As the clinical presentation of th e disease in the three patients who died was typical of toxic diphther ia, it is considered likely that the immunodiffusion test for toxin pr oduction in vitro may fail to detect strains of Corynebacterium diphth eriae producing toxin in vivo.