New approach for the identification of potentially toxigenic Corynebacterium sp. using a multiplex PCR assay.

In diphtheria laboratory examinations, the PCR test can be applied to isolates and clinical specimens. This study aimed to develop a PCR assay to identify the species and toxigenicity of diphtheria-causing bacteria, including the prediction of some NTTB types. Seven reference isolates, four synthetic DNA samples, 36 stored isolates, and 487 clinical samples used for PCR optimization. The PCR results was confirmed by DNA sequence analysis. The results of the PCR examination of the 7 reference isolates and 36 stored isolates were similar to the results obtained using conventional methods as gold standard, both for diphtheria-causing and non-diphtheria-causing bacteria. The validation of the PCR results using DNA sequence analysis showed that there was no mispriming or misamplification. The multiplex PCR assay developed in this study could correctly identify the species and toxigenicity of diphtheria-causing bacteria, including the prediction of some NTTB types not yet covered by established PCR methods.