Chromobacterium violaceum Infection

Introduction

Chromobacterium violaceum, a common inhabitant of soil and water, rarely causes human infection and is associated with high morbidity and mortality. Though the infection appears localized, it has a great propensity to disseminate by itself .

Aetiology

Chromobacterium violaceum is a gram-negative, motile bacteria. It is a facultative anaerobe. There are two strains which can be categorized as, pigmented and non-pigmented. The pigmented strain produces a violet, non-diffusible pigment called violacein that gives the bacterial colonies purple colour on agar medium. This pigment is an antioxidant, which is soluble in water, but insoluble in alcohol. Both strains are pathogenic.

Epidemiology

The organism is found as a saprophyte in soil and stagnant waters in tropical and sub-tropical regions. Wooley isolated the organism in a buffalo that had succumbed to a fatal infection in Philippines in 1905.¹ Since the description of human infection from Malaysia by Lessler in 1927, the cases have been reported from different parts of the world including India. However, the incidence has been very infrequent. Seven cases have been reported from India in the age group varying from 8 days to 24 years. Most of the cases are neonates and children. Three cases have been reported from Udipi,^2-4 one from Mangalore, Karnataka,⁵ one from Visakhapatanam, A.P.,6 West Bengal,⁷ and Chandigarh.⁸ The bacterium has been isolated from a wound over the scalp.⁹ Majority of the cases reported in the world are young adults. The infection presented as septicemia in a child.¹⁰

Pathology

Chromobacterium violaceum gains entry through broken skin exposed to the organism found in the soil and water.¹¹ It causes abscesses in skin and liver. Its haematogenous dissemination results in septicaemia. The organism grows well on ordinary laboratory media at 35-37 ^oC

Clinical manifestations

Chromobacterial infection presents with fever, pustular skin eruptions, multiple liver abscesses, urinary tract infection, pneumonia, and septicaemia. There can be features of meningitis. Diarrhoea can also be present. The patient appears pale with tachycardia and tachypnoea. Mild hepatosplenomegaly is also a common occurrence. Crackles can be observed on chest examination. The condition may present with symptoms ranging from localized skin and soft tissue infection to systemic infection.

Investigations

Anaemia, and polymorphonuclear leukocytosis can be commonly observed on haematological examination. Chest radiograph can show bilateral infiltrates. The anaerobic culture of the blood and pus from pustules will show growth of organism in violet-pigmented colonies with a smell of hydrogen peroxide.

Diagnosis

Chromobacterium infection is rare. Only 150 cases have been reported worldwide. This bacterium must be considered for differential diagnosis in cases of sepsis when abraded skin is exposed to soil or stagnant waters in tropical region.

Treatment

Chromobacterium exhibits low virulence. However, it can cause fatality due to septicaemia or meningitis. The organism is sensitive to drugs like pefloxacin, ciprofloxacin, chloramphenicol, amikacin, fluoroquinolones, carbapenems, cotrimoxazole, aminoglycosides, erythromycin, imipenem, and gentamicin. Drainage of abscess may be necessary. Fatal end can be prevented with prompt treatment.

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Conflict of interest

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