Melioidosis

For this organism, I start with one of rare case scenarios. This patient presented with 5-day of fever and right periorbital swelling & redness with neither eye pain nor blurred vision. His right-sided forehead was swollen with necrotic tissue.

Here is his CT brain & orbit. See periorbital abscesses, the hypodensity with ring-enhancing lesion at the medial aspect of medial rectus muscle of the right globe.

Here is his CT abdomen. The hypodensity lesion at segment 7 of right lobe liver indicates non-liquefied early abscess formation.

Hemoculture was detected the growth of thin-shaped gram negative rod.

In clinical specimens, these organism are bipolar-staining that look like safety pin. (in the circle)

The first few days of incubation, colonies have smooth, creamy white appearance on blood agar. When we incubate a plate for about a week, we will see a characteristic wrinkled colony of Burkholderia pseudomallei, the major cause of infection in Northeast of Thailand.

Pink or colorless colonies are detected on MacConkey agar.

TSI shows neutral butt with variable slant (neutral or acid).

Motility test is positive because B.pseudomallei has flagella. (1st tube from left)

Oxidase test is positive. Bacteria can produce cytochrome c oxidases that oxidize reagent such as N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD) or N,N-Dimethyl-p-phenylenediamine (DMPD) and turn into dark blue to maroon color. (same as Pseudomonas spp., Morexella spp., Bordetella spp.)