Septic shock caused by Chromobacterium haemolyticum following initial misidentification as Chromobacterium violaceum in China.

OBJECTIVES

We report a case of bloodstream infection caused by Chromobacterium haemolyticum in an 80-year-old man following traumatic exposure to contaminated rice field water. The patient presented with rapidly progressive lower extremity soft tissue infection and septic shock.

DESIGN OR

METHODS

Initial identification was performed using MALDI-TOF MS. Due to atypical phenotypic characteristics, including absence of violacein pigmentation and presence of β-hemolysis, whole-genome sequencing (WGS) was conducted for definitive species confirmation.

RESULT: Preliminary MALDI-TOF MS identification indicates that it is Chromobacterium violaceum; Definitive identification by whole-genome sequencing (WGS) confirmed C. haemolyticum. Antimicrobial susceptibility testing (AST) revealed high-level resistance to β-lactam antibiotics, including carbapenems, while the isolate remained susceptible to fluoroquinolones and tetracyclines. WGS identified the blaCRH-1 gene, likely contributing to the resistance phenotype.

CONCLUSION

This case emphasizes the importance of accurate species-level identification and AST in managing Chromobacterium infections, especially in immunocompromised or severely ill patients. Increased awareness of C. haemolyticum as a distinct clinical pathogen is essential, given its potential for misidentification and multidrug resistance.