Chromobacterium violaceum: A rare bacterium isolated from a wound over the scalp
A 42-year-old male came with a history of a fall from the bike 7 days earlier. He had fallen into a drainage canal containing stagnant water and sustained injuries on the head and both the legs. His head and face had been submerged in the drain water. He also gave history of loss of consciousness for half an hour. He was nondiabetic and normotensive, but was a chronic smoker.\nAfter the incident he was taken to a local hospital where the wound over the scalp, measuring about 6 × 1 cm [], was sutured and the abrasions on the legs dressed. He had been discharged with oral Ampiclox™ 500 mg TID on the following day. Over the next 5 days he developed pain and edema over the sutured area and was admitted to our hospital on the seventh day post injury.\nOn examination, the patient was conscious and alert. His vitals were normal. Local examination showed a wound that was edematous and discharging pus. The sutures were removed and a pus sample was collected with aseptic precautions and sent to the microbiology laboratory for bacteriological culture and antimicrobial susceptibility. The routine laboratory investigations showed: hemoglobin, 13.6 g/dl; total white blood cell count of 13000 cells/mm3, with 80% neutrophils; and fasting blood sugar, 70 mg/dl. CT scan (brain) was normal.\nGram stain of the discharge from the wound showed plenty of pus cells along with gram-negative pleomorphic rods. The sample was inoculated on nutrient agar, blood agar, and MacConkey agar and incubated aerobically at 37°C for 24 hours. The next day smooth, round, convex, butyrous, violet-colored colonies were noticed on all the three plates. On blood agar, deep violet colonies with beta-hemolysis was seen []. The organism was a facultatively anaerobic, motile, gram-negative rod. It was catalase and oxidase positive. Biochemically, indole, methyl red, and Voges-Proskauer test were negative. The organism fermented glucose (producing acid but no gas) and trehalose but did not ferment lactose or mannitol. Triple sugar iron medium showed.an alkaline slant and acid butt(K/A) without gas and H2S production. Citrate was utilized and nitrate was reduced. Arginine was decarboxylated but not lysine and ornithine. Biochemically, the isolate was identified as Chromobacterium violaceum.\nAntibiotic susceptibility of the organism was tested by the disc diffusion method []. The organism was found to be sensitive to gentamycin, chloramphenicol, ciprofloxacin, tetracycline, ceftazidime, imipenem, and amikacin. It showed intermediate sensitivity to cefotaxime but was resistant to penicillin and cephalexin.\nBased on the results of the antibiotic susceptibility testing, the patient was given injection gentamycin 80 mg IV twice a day for 7 days. With this treatment the wound healed completely. A repeat sample was collected the following day of first sample and the same organism was isolated again, which proved that the organism was a pathogen and not a contaminant. The patient was followed up for 15 days and the wound healed completely with no signs of recurrence or septicemia