[Diphtheria--isolation of an endemic Corynebacterium diphtheriae strain in Southern Lower Saxony].

After decades of only limited epidemiological and clinical importance diphtheria (especially of the upper respiratory tract) is regaining increasing interest of public health officials, as recent case reports in national and international publications clearly demonstrate. In March 1993 we observed a case of tracheobronchial Corynebacterium diphtheriae mitis infection in a 66-year old man from the South of Lower Saxony with clinical presentation of mucopurolent exacerbation of chronic bronchitis. The C. diphtheriae mitis strain was identified by microbiological and biochemical tests; however, its expression of toxin remains scientifically controversial. Investigations by the local public health officer suggest an endemic strain of C. diphtheriae. In this paper case report and results of investigations by the local public health officer are described in detail, stressing the need for widespread preventive inoculation not only in the younger but especially in the elderly population.