Background: Kocuria species are Gram-positive, aerobic cocci, and members of the Micrcoccaceae family that are known to be opportunistic pathogens. Although there have been sporadic reports of infections caused by Kocuria species, little is known regarding their human pathogenicity and clinical characteristics.
Case report: We herein report a case of a peripherally inserted central catheter (PICC)-related bloodstream infection caused by Kocuria marina in a 90-year-old Japanese with multiple cancer. The patient, who was admitted due to adhesive intestinal obstruction, suddenly developed sepsis on day 29 following admission. Three sets of blood cultures and a culture of the PICC tip revealed the growth of Gram-positive cocci arranged in clusters. The patient improved quickly after treatment with an antimicrobial agent and catheter removal. The organism was identified as Kocuria varians using the MicroScan Walkaway system and K. varians/Kocuria rosea with a 99.7% probability using an API Staph system. However, 16S rRNA gene sequencing analysis identified the pathogen as K. marina.
Conclusion: Although K. marina is a rare pathogen, physicians should consider it in case of catheter-related infections in patients with serious underlying conditions. As commercial identification systems can misidentify species within the Kocuria genus, the use of genomic methods such as 16S rRNA sequencing and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry may be useful for the precise identification of Kocuria to the species level.
Keywords: 16S rRNA sequencing; Catheter-related blood stream infection; Kocuria marina; Kocuria species.