2018 Volume 67 Issue 3 Pages 299-306
Most Corynebacterium species are gram-positive, rod- shaped bacilli. Here, we report on Corynebacterium showing a coccoid form similar to Staphylococcus detected from positive blood culture bottles. We performed several cultivation methods to study the presence or absence of possible morphological changes, identify particular species showing these changes, and evaluate the causes of the changes. In addition, we conducted further experiments on Corynebacterium strains that showed a coccoid form, when classified using MicroScan Panels. Moreover, we investigated the drug sensitivity rate of Corynebacterium species. The results showed that Corynebacterium striatum and Corynebacterium simulans presented a coccoid form when cultivated using liquid media under anaerobic conditions. Furthermore, the strains showing a coccoid form were identified as Micrococcus spp. using MicroScan Panels. Of the antibiotics tested, all strains were susceptible to vancomycin (VCM). However, many strains only showed susceptibility to VCM and were highly resistant to other antibiotics tested. Corynebacterium strains are identified as common contaminants detected from blood cultures. Despite the reports as contaminants, a high percentage of isolates showed resistance to many antibiotics. In addition, Corynebacterium strains are reported as the causes of nosocomial infections. In summary, we found that misidentification of Corynebacterium strains from blood cultures is a clinically significant problem that can lead to poor outcomes in patients, highlighting the importance of accurate clinical results.
