[Diphtheroids and nontoxigenic Corynebacterium diphtheriae in the etiology of diphtheria]

The review raises a problem of cooperation between a laboratory and clinics for diphtheria diagnosis. According to scientific literature nontoxigenic diphtheroids cause different nosocomial infections of immunocompromised patients. Nontoxigenic Corynebacterium diphtheriae may cause such systemic infections as septic arthritis and endocarditis in people belonging to unsecured strata of the society. A toxin which can be produced not only by C. diphtheriae but also by diphtheroids is the sole reason of diphtheric inflammation. The role of the C. diphtheriae nontoxigenic strains should be elucidated by the improving of standard methods and introduction of the methods of molecular biology for the toxigenicity assay of diphtheria strains (e.g. polymerase chain reaction). But a complexity of gene expression and difficulties in distinguishing between the infection and the microorganism colonization of a vaccinated person reserve the last word in the diagnosis of diphtheria for a clinical physician.