Chromobacterium violaceum

Background

Microbiology

• Gram-negative oxidase-positive bacillus
  • The violacein pigment is produced during aerobic growth at 22 ºC and can interfere with the oxidase test
• Colonies are deep purple to black due to the presence of the violacein pigment and may have an almond-like odor
• Found in water and soil, primarily tropics or subtropics

Epidemiology

• Mostly tropical or subtropical areas, especially southeast Asia
• Also in southeast US, most commonly Florida
• CGD is a risk factor for opportunistic infection, as is G6PD deficiency

Clinical Manifestations

• Causes wound infections following contaminated water exposure
• Typically starts with a cellulitis
• Always with systemic features, including fever (100%) and sepsis (82%)
• Often bacteremia (60%) and can cause abscesses in visceral organs (51%), especially lung and liver
• High mortality (53%)

Differential Diagnosis

• Includes other causes of skin and soft tissue infection after water exposure
• Common bugs: Staphylococcus aureus, Streptococcus pyogenes, other streptococci, Klebsiella, Pseudomonas aeruginosa, Escherichia coli, and polymicrobial infections
• Uniquely marine bacteria: Aeromonas, Vibrio vulnificus, Shewanella, Edwardsiella, Chromobacterium
• Others: Burkholderia pseudomallei, non-tuberculous mycobacteria, and some fungi

Management

• Fluoroquinolones, chloramphenicol, tetracyline, TMP-SMX, imipenem, gentamicin
• Maybe cefotaxime, ceftazidime, imipenem
• Avoid first- and second-generation cephalosporins

Further Reading

• Chromobacterium violaceum infection: a clinical review of an important but neglected infection. J Chin Med Assoc. 2011;74(10):435-41.