Chromobacterium violaceum is aGram-negative,facultativeanaerobic, non-sporingcoccobacillus. It is motile with the help of a singleflagellum which is located at the pole of the coccobacillus. Usually, there are one or two more lateral flagella as well.[1] It is part of the normal flora of water and soil of tropical and sub-tropical regions of the world. It produces a natural antibiotic calledviolacein, which may be useful for the treatment of colon and other cancers.[2] It grows readily on nutrient agar, producing distinctive smooth low convex colonies with a characteristic striking dark violet metallic sheen (due to violacein production).[3] Some strains of the bacteria which do not produce this pigment have also been reported.[4] It has the ability to break downtarballs.[5]
C. violaceum fermentsglucose,trehalose,N-acetylglucosamine andgluconate but not L-arabinose, D-galactose, or D-maltose. It is positive for catalase and oxidase reactions.[1] Bacterialisolates in many cases can show high level resistance to a range of antibiotics.[6]
C. violaceum rarely infects humans, but when it does it causes skin lesions,sepsis, andliver abscesses that may be fatal.[7] The first reported case ofChromobacterium violaceum infection in humans in literature is from Malaysia in 1927.[1] Only 150 cases have been reported in literature since then.[8] To date, cases have been reported from Argentina, Australia, Brazil, Canada, Cuba, India, Japan, Nigeria, Singapore, Sri Lanka, Taiwan, United States and Vietnam. The most common mode of entry of the bacteria into the body is through the injured skin coming in contact with soil or water containing the bacteria.[1][9] The disease usually starts as a limited infection of the skin at the point of entry of the bacteria, which progresses to necrotizing metastatic lesions, then multiple abscesses of the liver, lung, spleen, skin, lymph nodes or brain, leading to severe septicaemia, culminating in multiorgan failure which may be fatal.[10] Other reported pathologies include chronic granulomatosis, osteomyelitis, cellulitis, diarrhoea, septic spondylitis, conjunctivitis, periorbital and ocular infection.[1][11][12][13][14] Care must be taken becauseBurkholderia pseudomallei is commonly misidentified asC. violaceum by many common identification methods.[15][16] The two are readily distinguished becauseB. pseudomallei produces large wrinkled colonies, whereasC. violaceum produces a distinctive violet pigment.
C. violaceum produces a number of natural antibiotics:
Infection caused byC. violaceum is rare, therefore there are no clinical trials evaluating different treatments. Antibiotics that have been used to successfully treatC. violaceum includepefloxacin,[4]ciprofloxacin,amikacin,[1] andco-trimoxazole.[18] Other antibiotics that appear to be effectivein vitro includechloramphenicol andtetracycline.[19] For theoretical reasons, infection would not be expected to respond topenicillins,cephalosporins, oraztreonam, althoughcarbapenems likemeropenem orimipenem may possibly work.[20] Though the bacteria is reported to be resistant to first generation cephalosporins, susceptibility to the newer cephalosporins is variable.[21]
The complete genome was sequenced and the results were published in 2003.C. violaceum type strain ATCC 12472 was found to have 4,751,080base pairs with a G + C content of 64.83% and 4,431ORFs.[3]
^Itah AY, Essien JP (2005). "Growth Profile and Hydrocarbonoclastic Potential of Microorganisms Isolated from Tarballs in the Bight of Bonny, Nigeria".World Journal of Microbiology and Biotechnology.21 (6–7):1317–22.doi:10.1007/s11274-004-6694-z.S2CID84888286.
^Chou, YL; Yang ., PY; Huang, CC; Leu, HS; Tsao, TC (2000). "Fatal and non-fatal chromobacterial septicemia: report of two cases".Chang Gung Med J.23 (8):492–7.PMID11039252.
^Howard, AJ; Ison, CA (1996). "Haemophilus, Gardnerella and other bacilli". In Collee, JG; Fraser, AG; Marmion, BP; Simmons, A (eds.).Mackie and McCartney Practical Medical Microbiology (14th ed.). New York: Churchill Livingstone. pp. 329–41.
