During a vacation in the Turks and Caicos a woman was bitten several times by unidentified insects. She presumed that an expanding lesion on her forearm was an infection of one of the bites. She was seen by a physician and had the lesion lanced producing a fair amount of purulent drainage. However, the lesion did not resolve and she sought medical attention when she got home. She was not systemically unwell and this is what it looked like at that time:
A routine culture and susceptibility was performed. After 2 days of incubation there were small, white, “heaped up” colonies visible of the blood agar plate. This is what the plate looked like 1 or 2 days later:
And this is a close-up of the colonies viewed through a stereoscope:
She was investigated for pulmonary nocardiosis but no other focus was found. The arm lesion resolved completely within several weeks on therapy with trimethoprim/sulfamethoxazole.
Nocardia are filamentous, branching, Gram-positive bacilli that are found world-wide in soil. People get infected with them by inhalation or direct physical contact with material containing the organisms. Person to person spread does not occur.
The incidence of nocardiosis is likely rising as a result of increasing numbers of immuno-compromised people, a factor that does not appear to be important in this case. The rapid resolution with therapy and no documentation of spread systemically is consistent with normal immune function.
For more information about Nocardia see http://www.cdc.gov/nocardiosis/index.html
Category: Skin and Soft Tissue Infection