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Our first "Bug Challenge" comes from Mahosot Hospital, Vientiane, Laos and was contributed by Dr David Dance who works as a Clinical Microbiologist there. 


The bacterium pictured (on blood agar here and on chocolate agar here) was isolated from blood cultures of a 53 year old, previously healthy farmer from northern Laos who presented with an acute febrile illness associated with chills, severe headaches, nausea and vomiting, a cough productive of white sputum, with crepitations audible at the left lung base but no abnormalities on Chest X ray. He had a normochromic anemia and a WBC count of 7.5 109/L (neutrophils 70%, lymphocytes 30%). An abdominal ultrasound demonstrated a diffusely enlarged liver without focal lesions and mild splenomegaly. Despite treatment with ampicillin followed by ceftriaxone, the patient deteriorated and died with evidence of multi-organ failure and disseminated intravascular coagulation over the next 3 days. 

The colonies on blood and chocolate agar were approximately 1-2mm after 24 hours incubation in air at 35°C, and were deeply violet pigmented.  Gram stain revealed a Gram negative bacillus. The organism was sensitive to gentamicin, chloramphenicol, ofloxacin, ciprofloxacin, co-trimoxazole, imipenem, and resistant to ampicillin, ceftriaxone, and ceftazidime by disc diffusion testing.


1.What is the likely identity of the organism?

2.How would you do an oxidase test on this organism?


This resource was originally posted in Global Health Microbiology

  • hrogier hrogier 13 Jun 2012

    Chromobacterium violaceum