Corynebacterium pseudodiphtheriticum as a pathogen in bacterial co-infection in COVID-19 patients with mechanical ventilation.

Many studies have been conducted on ventilator-associated complications (VACs) in COVID-19 patients. However, in these studies, the causative organisms were similar, and there are no reports on VAC corresponding with Corynebacteria. Coryneforms are frequently cultured in polymicrobial infections and are usually considered contaminants in respiratory specimens. However today, Corynebacterium pseudodiphtheriticum or striatum is known to be a pathogen in lower respiratory tract infection. We report three cases of VAC probably due to Corynebacterium pseudodiphtheriticum in COVID-19 patients. If purulent lower respiratory specimens showed coryneform predominantly via Gram staining, empirical therapy should be started. Furthermore, species identification and drug susceptibility testing should be performed.