The results of comparative experimental studies of identification of nontoxigenic C. diphtheriae strain by three different commercial laboratories are presented. A typical nontoxigenic strain of C. diphtheriae biovar mitis was used. For the studies, three lines of ten-fold dilutions of bacterial culture were prepared, followed by control planting on the medium and counting CFU/ml. In the experiment, tampons were pooled with a 24-hour bacterial culture of a nontoxigenic C. diphtheriae strain. Tampons were provided from three different laboratories - ∑-Transwab® with Ames liquid medium (from the first and second laboratories) and a viscose tampon with coal medium (from the third laboratory). After pooled, tampons were delivered to commercial laboratories. And as a result of the experiment, Corynebacterium spp. was identified in first laboratory (103 CFU/tamp), S. epidermidis (102 CFU/ml) - in second laboratory and nontoxigenic C. diphtheriae biovar gravis - in third laboratory. The study indicates that there is a need to the supervision of bacteriological investigations conducted in various laboratories. This will improve the quality of investigations on diphtheria infection and identify of diphtheria carrier, which is a reservoir of the causative agent of diphtheria, and will contribute to the maintenance of sanitary and epidemiological well-being in our country.
Keywords: Corynebacterium diphtheriae; bacteriological diagnosis.