Latent tuberculosis in a patient vaccinated with BCG?Thank you for addressing the ongoing disinformation on the BCG vaccine. I also have had problems with providers not following up on positive skin tests in patients vaccinated more than 15 years earlier.
My mother received the BCG vaccine as a young child in Australia. She had a wildly positive skin test at age 50 years when she applied for a job at a hospital in California. A chest x-ray was negative, so she was not treated and was hired. Her skin test took weeks to heal and was as big around as a 6-oz can.
Now at age 89 years, a mass has been identified in the extra-esophageal area near her liver. It was biopsied and found not to be TB, but I am not sure the collection or testing was valid. After three weeks of amoxicillin (Augmentin), the mass was diminished in size and no longer caused dysphagia. That was one year ago, and now she is again having difficulty swallowing. All testing continues to be negative, including endoscopy and barium swallow, but the mass is bigger. — Jan Morgan, FNP-C, FAAPM, Hoodsport, Wash.
The description of this cases raises several questions. First, was CT imaging done? CT is often more accurate in determining caseinating lesions than plain films. Second, was the initial biopsy specimen sent for long-term microbial testing for acid-fast bacilli? Finally, does the patient then or now have any other symptoms, such as fatigue and weight loss?
The large, positive reaction to the PPD at age 50 years was more than likely not due entirely to previous BCG vaccination.
In such cases as this, the QuantiFERON-TB Gold test may be used in place of the PPD. This blood test detects interferon-gamma in the serum of people sensitized to Mycobacterium tuberculosis, but is not widely used and is quite expensive.
While all clinicians are taught that PPD response following BCG vaccine is typically positive, the response varies with age at vaccination, number of years since vaccination, number of times vaccinated, and number of PPDs performed. This detailed information is rarely available, making current diagnosis and treatment difficult. According to the U.S. Preventive Services Task Force, an induration of >10 mm should not be attributed to prior BCG vaccination. — Sherril Sego, FNP-C, DNP (153-10)