The carcass of a three-year-old male Chinese Red panda (Ailurus fulgens styani) was submitted to the veterinary diagnostic laboratory at North Dakota State University in November of 1998. One week previously, the animal had been transported from a Florida zoo to the local zoological park. Clinical signs during that week included listlessness, inappetance, and death on the morning of the seventh day. Gross lesions included an interscapular, subcutaneous abscess; subcutaneous edema of the cervical region with extension down the right arm; purulent inflammation of the right superficial cervical lymph node; severe, bilateral, multifocal pulmonary abscesses; diffuse mottling of the liver and a single splenic abscess. Microscopic lesions consisted of extensive, irregular foci of necrosis and suppurative inflammation in the lung, liver, spleen, and superficial cervical lymph node. In the case of the lung, inflammation and necrosis extended to and included the visceral pleura. Chromobacterium violaceum was isolated from cultures of lung, liver, spleen, and a swab from the interscapular abscess. Suspensions of C. violaceum were inoculated intraperitoneally in Swiss Webster mice. Eighteen hours post-inoculation the mice died and C. violaceum was cultured from liver, lung, and spleen.
Chromobacterium violaceum are a species of bacteria that are Gram-negative, non-sporing, non-acid fast small rods or coccobacilli. They are 0.6-0.9µm x 1.5-3.0µm in size and exhibit bipolar staining. Motility of C. violaceum is achieved by means of a single polar flagellum and up to four antigenically and structurally distinct lateral flagellae. They are considered as normal flora of soil and water in tropical to subtropical areas where they may play a role in the rhizosphere. These bacteria are not present as part of the normal flora of humans or animals.
C. violaceum are facultative anaerobes with a growth range from 15-40°C. Optimal growth is achieved at 30-35°C. They characteristically produce violet colonies on nutrient agar and usually grow on MacConkey agar. Colonies grow easily on common culture media, which are suitable for the isolation of strains from patient specimens. However, these are not the best media to isolate these organisms from soil or water because they are present in only small numbers. Sterile rice grains and reduced strength nutrient agar have been successfully used to isolate them from soil or water. Colonies are low convex, violet, smooth, and not gelatinous. The pigment produced by most strains is violacein, which gives the colonies a distinctive metallic, dark purple sheen.
C. violaceum are pathogenic and occasionally cause serious pyogenic or septicemic infections of mammals, including man. Strains of virulent Chromobacterium produce an endotoxin, which is more reactive than that from avirulent ones. Virulent strains are able to survive attack from phagocytic cells by elevated levels of superoxide dismutase and catalase. Infections due to soil or water contamination with the organisms can be quite varied, ranging from mild diarrhea to septicemia leading to a rapid death. Liver and lung abscesses have been reported and similar infections in animals have been reported. The veterinary literature documents infections in swine and Barbary sheep (pleuropneumonia) and gibbons, Assam macaques, and dogs (septicemia). Human infections are reported from several continents, particularly Australia, South America, and Southeast Asia where the typical disease presentation includes cutaneous inflammation, sepsis, and liver abscesses. Ocular infections are documented in the more recent literature. Human chromobacterial sepsis in the United States is reported primarily from Florida and Louisiana. There are currently no vaccines.
The biochemistry of Chromobacterium violaceum includes acid production from glucose, trehalose, N-acetylglucosamine and gluconate but not L-arabinose, D-galactose or D-maltose. They can produce cyanide, utilize Lactate, hydrolyze Casein, decarboxylate arginine, reduce nitrate to nitrite and ferment carbohydrates. They are oxidase-positive and catalase-positive. The GC content of the DNA is 65-68 mol% but there have not been many studies on the genetics of these organisms.
Chromobacterium violaceum could be used for the production of violacein, which has antibiotic characteristics particularly against soil amoebae and trypanosomes. It can also be used to assay for L-tryptophan. C. violaceum does not regulate any of its tryptophan genes transcriptionally. It uses the amino acid tryptophan to synthesize the antibiotic violaceum.
Chromobacterium violaceum also produces other antibiotics:
- Aerocyanidine is active against Gram-positive organisms.
- Aerocavin is active against Gram-positive and Gram-negative organisms.
- 3,6-dihydroxyindoxazene and Factor Y-T0678H (6-hydroxy-3-oxo-1,2-benzisoxazolin) are both active against Gram-negative bacteria.
A number of other important compounds are produced by C. violaceum including substances that enhance the immune response, compounds that act synergistically with beta-lactam antibiotics.
It has been suggested that C. violaceum strains can be used for the extraction of gold from soil. As a result of the production of cyanide, which reacts with the gold to form the complex anion [Au(CN)2]-, the gold is solublised and easily extracted.
References:
- Tucker RE; Winter WG Jr; Wilson HD. Osteomyelitis associated with Chromobacterium violaceum sepsis: A case report. J Bone Joint Surg. [Am] 1979 Sep;61(6A):949-51 (ISSN: 0021-9355)
- N.W. Dyer, DVM, MS. "Chromobacterium violaceum septicemia in a Chinese Red Panda." [online] November 1998. < http://www.ndsu.nodak.edu/ndsu/veterinary_science/vetdiag/case.htm>
- RIDOM. "Description of Chromobacterium violaceum." [online] 2 January 1999. < http://www.ridom.hygiene.uni-wuerzburg.de/ridom/tmp/d8h/speciesDescription.html>
- RIDOM. "Chocolate blood agar after 48 hours of incubation at 26 0C" [online image] 2 January 1999. <http://www.ridom.hygiene.uni-wuerzburg.de/ridom/tmp/d8h/speciesDescription.html>
- RIDOM. "Gram Stain" [online image] 2 January 1999. <http://www.ridom.hygiene.uni-wuerzburg.de/ridom/tmp/d8h/speciesDescription.html
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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