# Chromobacterium haemolyticum Infection Subsequent to Experiencing a Traumatic Event in a Rice Field: A Case Report and Literature Review

## TL;DR

A rare case of Chromobacterium haemolyticum infection is reported, highlighting its misidentification as C. violaceum and better clinical outcomes.

## Contribution

This case report clarifies the clinical distinction between C. haemolyticum and C. violaceum infections.

## Key findings

- C. haemolyticum was misidentified as C. violaceum using automated systems but confirmed via 16S rRNA analysis.
- The patient recovered without abscess formation or recurrence after a short antibiotic course.
- C. haemolyticum infections may have lower mortality and recurrence rates than C. violaceum.

## Abstract

The incidence of infections caused by Chromobacterium haemolyticum, phylogenetically related however distinct from Chromobacterium violaceum, has increased since its identification in 2008. Differences in their unique microbiological features have been highlighted, particularly regarding their phenotypic distinctions in the colony pigmentation and hemolysis. This is largely due to C. haemolyticum being misidentified as C. violaceum, using the current automated microbial identification systems. However, clinical aspects and outcomes of C. haemolyticum infections remain unclear as few clinically relevant cases have been reported and considered similar to C. violaceum infections. Consequently, we reported an extremely rare case of C. haemolyticum bacteremia, which was initially diagnosed as a C. violaceum infection, however was later confirmed to be a C. haemolyticum infection, using 16S ribosomal ribonucleic acid (rRNA) sequence analysis. Abscess formation was not observed, and the patient was treated with a short course of antibiotics. Ultimately, his condition resolved, without recurrence during the 1-year follow-up. Clinicians should be aware that if the isolated organism is originally identified as C. violaceum, however is phenotypically mismatched with colony nonpigmentation and beta-hemolysis; the organism may be C. haemolyticum. Mortality, abscess formation, and recurrence rates are lower than those of C. violaceum, and chronic broad-spectrum antibiotic suppression may not be required, potentially avoiding unnecessary antibiotic use and preventing multidrug resistance.