What's That Pustule?!? Bringing Mass Spectrometry to the Bedside

1Medical College of Wisconsin, Milwaukee, WI
2Medical College of Wisconsin, Milwaukee, WI
3Medical College of Wisconsin, Milwaukee, WI

Meeting: Hospital Medicine 2013, May 16-19, National Harbor, Md.

Abstract number: 343

Case Presentation:

A 66‐year‐old immune‐compromised woman with systemic lupus erythematosus, antiphospholipid antibody syndrome, and adrenal insufficiency was admitted to the hospital due to a 2‐week history of painful skin lesions and associated swelling on her extremities. Four months prior to admission, her immunosuppressive therapy was switched from azathioprine (AZA) to mycophenolate mofetil (MMF) because of an episode of acute pancreatitis induced by the AZA. MMF was discontinued when a rash appeared a month prior to admission, and her prednisone was increased. On physical exam, she was afebrile with stable vitals. Examination of skin revealed multiple tender hemorrhagic pustules of various sizes concentrated on the left leg, right upper arm, and right hip. The rest of the physical exam was unremarkable. CT of chest revealed a 2.1‐cm nodule in the right lower lung along with multiple smaller bilateral pulmonary nodules. CT of the head was benign. Cultures from the cutaneous lesions showed branching gram‐positive rods, consistent with Nocardia. Mass spectrometry testing was performed in our lab and results were consistent with Nocardia brasiliensis. Because of this, she was started on TMP‐SMX and meropenem. Verification culture later confirmed Nocardia brasiliensis.


There are 33 different pathogenic species of Nocardia reported. Each species of Nocardia has a different antibiotic sensitivity profile. Although it is not difficult to identify the Nocardia genus, speciation takes weeks and therefore may delay treatment. Mass spectrometry is used in Europe to aid in clinical diagnosis of isolates, but is not yet approved for clinical use in the United States. However, by utilizing mass spectrometry for our patient, we were able to empirically and accurately treat for disseminated Nocardia brasiliensis while the official cultures remained unavailable for weeks.


Disseminated nocardiosis is a rare, but serious disease in immune‐compromised patients. However, prognosis is good if treated with appropriate antibiotics. Because there are many different species of Nocardia with different treatment recommendations, the challenge of treatment lies in rapid identification of the species involved. Mass spectrometry is an available and efficient method of diagnosis that we successfully used and can be used to treat other patients.

To cite this abstract:

Fisher E, Rogers B, Takahashi D. What's That Pustule?!? Bringing Mass Spectrometry to the Bedside. Abstract published at Hospital Medicine 2013, May 16-19, National Harbor, Md. Abstract 343. Journal of Hospital Medicine. 2013; 8 (suppl 2). https://www.shmabstracts.com/abstract/whats-that-pustule-bringing-mass-spectrometry-to-the-bedside/. Accessed April 2, 2020.

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