Division of Infectious Diseases

Case of the month - June 2016



A 49 year old man was hospitalized for pneumonia. He had been in good health until four days before hospitalization, when he 
developed fever, pleuritic pain, and a productive cough.

His only previous medical history was another bout of pneumonia about ten years previously.
He was not on any medications, had no sick contacts, and did not use tobacco or alcohol, although he smoked a lot of
marijuana every day.

On physical exam, left-sided rhonchi were present. A chest X-ray was done (Figure 1). Vancomycin and ceftriaxone were started. 
The cavitary lesion surrounded by an infiltrate was confirmed on a CT scan of the thorax (there were no additional findings). 

A bronchoalveloar lavage was done. Photos of the Gram stain (Figure 2) and growth on blood and MaConkey agars from
the bacterial culture (Figure 3) are shown below. The microbiology technologist noted that the organism was a small
Gram-negative rod that was lactose-negative and both oxidase and catalase positive. After 24 hours, the organism also
demonstrated the ability to oxidize xylose. It was susceptible to meropenem but resistant to all penicillins, cephalosporins,
trimethoprim-sulfamethoxazole, aztreonam, aminoglycosides, and colistin.

Answer: lung abscess caused by Achromobacter xylosoxidans
What is the organism? /uploadedImages/departments/medicine/Divisions/Infectious_Diseases/June-2016-CXR.png
Figure 1: Chest X-ray with cavitory infiltrate (click on image to enlarge)
 /uploadedImages/departments/medicine/Divisions/Infectious_Diseases/June-2016-Gram stain.png
Figure 2: Gram stain fo BAL fluid (click on image to enlarge)


/uploadedImages/departments/medicine/Divisions/Infectious_Diseases/June-2016-BAL culture.jpg 




 Figure 3: Colonies from BAL fluid culture (click on image to enlarge)



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