Severe Pneumonia Caused by Corynebacterium striatum in Adults, Seoul, South Korea, 2014–2019

We investigated the proportion and characteristics of severe Corynebacterium striatum pneumonia in South Korea during 2014–2019. As part of an ongoing observational study of severe pneumonia among adult patients, we identified 27 severe C. striatum pneumonia cases. Most (70.4%) cases were hospital-acquired, and 51.9% of patients were immunocompromised. C. striatum cases among patients with severe hospital-acquired pneumonia (HAP) increased from 1.0% (2/200) during 2014–2015 to 5.4% (10/185) during 2018–2019, but methicillin-resistant Staphylococcus aureus (MRSA) infections among severe HAP cases decreased from 12.0% to 2.7% during the same timeframe. During 2018–2019, C. striatum was responsible for 13.3% of severe HAP cases from which bacterial pathogens were identified. The 90-day mortality rates were similarly high in the C. striatum and MRSA groups. C. striatum was a major cause of severe HAP and had high mortality rates. This pathogen is emerging as a possible cause for severe pneumonia, especially among immunocompromised patients.