Is that Something in the Air Bipolaris?


In 2013, prompted by infections in 2 Texas patients, the CDC was asked to investigate mysterious cases of a rare mold infection known as Bipolaris in cardiac surgery patients. The results of that investigation were recently published in Medical Mycology and contain some interesting findings. 

Bipolaris is a rare fungus that is not a well-characterized cause of surgical infection and is considered a rare infectious agent, preying on the immunosuppressed as most organisms like this do. Brain abscesses and subcutaneous skin infections are two types of infection Bipolaris is known to cause. Bipolaris infections are known as phaeohyphomycosis because of their pigmented cell walls ("black mold").

Prompted by the initial 2 cases and concern for a possibly contaminated medical product, the CDC conducted an expanded investigation and uncovered a total of 23 cases of Bipolaris infection that occurred in Texas, Arkansas, and Florida between 2008-2013.

Some important points about the cases included:

  • Median age of 55
  • 1/3 were heart transplant patients
  • 52% were receiving immunosuppressant medications
  • Delayed sternal closure in the majority of patients
  • Median days of having an open chest was 8 days
  • 40% had an emergency bed-side procedure for bleeding
  • 76% of patients died

The CDC discusses what may have been behind some of these infections and hypothesizes that procedures performed in rooms without positive pressure to the environment, in which ubiquitous environmental mold spores could enter and find their way to an open chest, may have played a role. 

In the discussion section of the paper the authors mention that no formal surveillance for invasive mold infections of this sort is performed. It seems to me that the Bipolaris outbreak and the elucidation of risk factors are important benefits that will accrue from such surveillance. As common-source outbreaks involving mold may be less common than their bacterial counterparts, it is minimizing and mitigating known risks that takes on greater importance.