Clinical relevance and impact of Corynebacterium isolation in lower respiratory tract of critically ill patients requiring mechanical ventilation

Purpose Corynebacterium spp. (C. spp.) is commonly considered as a contaminant in respiratory specimens. No study has ever focused on its clinical relevance in the lower respiratory tract of patients admitted to the intensive care unit (ICU) and requiring mechanical ventilation. The aims were to describe the characteristics of ICU patients with a C. spp. positive deep respiratory specimen, to investigate the impact of C. spp. on the occurrence of pneumonia, and to evaluate the outcomes of these pneumonia. Methods We retrospectively included all adult patients admitted to ICU in a 1000-bed University Hospital (2007–2017) who had a C. spp. positive lower respiratory tract specimen at a significant quantitative level. We used clinical, radiological, and microbiological criteria to classify the likelihood of such pneumonia. Results Among the 31 patients included, acute respiratory failure and postoperative care after major surgery were the main reasons of admission. SAPS II was 47 [34–60]. C. spp. pneumonia was considered as probable, possible and unlikely in 10, 14, and 7 patients, respectively. Fifty-two and 94% of C. spp. strains were sensitive to amoxicillin, and vancomycin/linezolid, respectively. Seventeen patients had a complete course of antibiotic against C. spp. The overall ICU mortality was 58%. Conclusion Corynebacterium spp seems to be responsible for authentic pneumonia in mechanically ventilated patients. It should be considered as clinically relevant when predominantly present in respiratory specimen from patients suspected with pneumonia in ICU, and empirically treated.