Corynebacterium pseudodiphtheriticum as etiologic agent of human infections worldwide: a review of case reports within the last 40 years (1983-2023).

Corynebacterium pseudodiphtheriticum has been increasingly reported as an etiologic agent of both community-acquired and nosocomial infections, despite its common presence as a harmless member of the human upper respiratory tract and skin microbiota. However, infections caused by C. pseudodiphtheriticum and other corynebacterial species are still frequently misclassified as contamination and overlooked during clinical and laboratory diagnoses in several countries. In this study, an extensive review of human infections and nosocomial outbreaks caused by C. pseudodiphtheriticum was conducted through the analysis of reported cases from various countries, over a 40-year period (1983-2023). This review highlights the dichotomous nature of C. pseudodiphtheriticum, emphasizing both its potential biotechnological applications and its role as a human pathobiont affecting immunocompromised and immunocompetent individuals worldwide. Therefore, this study supports the inclusion of C. pseudodiphtheriticum in the list of clinically relevant pathogens and underscores the need for research into the virulence mechanisms involved in its pathogenesis.