Case 432 -- Ghost Mycobacteria on Gram Stain

Contributed by Andrew Walls, MD and A. William Pasculle, ScD
Published on line in July 2005


The patient was a 37-year-old African American woman with a history of poorly treated HIV infection, diagnosed in 2001, with progression to AIDS. A recent CD4 count showed 7 cells / cubic millimeter with a viral load of 745,000 copies / milliliter. She presented to the emergency department with fever up to 102.3 degrees Fahrenheit and a cough productive of yellow sputum with no hemoptysis. She denied any recent weight loss. She denied ever having a positive PPD, but could not remember when she was last tested. She had been admitted 6 months previously for similar symptoms, and all cultures were negative except for the stool, which was positive for non-tuberculous mycobacteria.

On admission, she was being treated with atazanavir and ritonavir, but she had been poorly compliant. She had previously been taken off of the medications due to elevated liver enzymes and mild scleral icterus. She was currently living with an HIV negative man who had been recently incarcerated and had subsequently lived in a halfway house. She was a 30-40 pack year smoker, and had admitted to alcohol, cocaine and crack use, but denied intravenous drug use.

Her vital signs were normal and her lungs were clear. Laboratory values showed a white blood cell count of 7200 / cubic millimeter and a differential of 45% neutrophils, 23% bands, 14% lymphocytes, 17 % monocytes, and 1% eosinophils. She was mildly anemic. Indices of kidney function were normal, and urinalysis was negative. A chest x-ray revealed an abscess or cavitary mass in the left upper lobe, and CT of the chest showed left upper lobe consolidation with central cavitation, and mediastinal and hilar lymphadenopathy. (Figures 1 and 2)

She was placed in respiratory isolation, and sputum samples were collected for 3 consecutive mornings. She remained febrile to 39.7 degrees Celsius with a cough but no respiratory distress. Blood cultures were negative. Sputum was submitted for acid-fast bacilli (AFB) smear and culture, as well as routine culture. The Gram stain showed moderate beaded Gram-positive rods, few Gram-positive cocci in clusters, and moderate white blood cells. The routine sputum culture grew only normal oral flora, but the mycobacterial culture became positive in 5 days for an acid-fast bacillus. Figure 3 shows the gram stain. All 3 AFB smears also contained "many acid-fast bacilli". (Figure 4). Figure 5 shows the colonial morphology of the mycobacterial isolate.


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