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Study Detects Tuberculosis DNA in Respiratory Samples from Boston Hospital Patients

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Study Suggests Current TB Diagnostics May Miss Cases in Boston Hospitals

"Our ultrasensitive test is detecting Mycobacterium tuberculosis DNA in patients who are unlikely to be diagnosed with TB using current methods." — Dr. Guillermo Madico, Boston University NEIDL

A study by Boston University researchers has detected genetic material from the bacterium that causes tuberculosis in a significant percentage of respiratory samples from patients at two Boston hospitals. The findings, published in the journal Nature Communications, suggest current diagnostic methods may not capture the full scope of tuberculosis-related disease in certain patient groups, though the clinical implications require further study.

Study Overview and Methodology

Researchers from Boston University conducted three separate studies over a six-year period, analyzing 297 respiratory samples from patients hospitalized at Boston Medical Center and St. Elizabeth's Medical Center.

The analysis used an ultrasensitive molecular test called the Totally Optimized PCR (TOP) TB assay. This test is designed to detect DNA from Mycobacterium tuberculosis, the bacterium that causes tuberculosis, by targeting a gene involved in its cell wall assembly. The assay has been validated in studies involving over 400 patients with suspected tuberculosis in Uganda, Brazil, and the United States.

The TOP TB assay is currently a research-use-only tool and is pending regulatory clearance for clinical use.

Key Findings

The study reported several specific findings:

  • Detection Rate: The TOP TB assay detected M. tuberculosis DNA in 12% to 16% of the respiratory samples tested. The researchers noted this prevalence was higher than expected given the low incidence rate of active tuberculosis disease in the Boston area.
  • Patient Demographics: The samples came from predominantly U.S.-born patients. Seventy-five percent of the patients who tested positive for TB DNA were aged 50 or older.
  • Comparison with Standard Tests: The TB DNA was detected in samples that had tested negative using conventional diagnostic methods, including mycobacterial cultures and other molecular tests. Furthermore, most patients who tested positive for TB DNA also tested negative on standard tuberculosis infection tests, such as tuberculin skin tests or interferon-gamma release assays.
  • Association with Specific Condition: All three patients diagnosed with acute chest syndrome, a complication of sickle cell disease, during the study period tested positive for TB DNA.

Researcher Statements and Interpretation

In statements provided with the study, researchers offered their interpretation of the findings.

Dr. Guillermo Madico, a scientist at Boston University's National Emerging Infectious Diseases Laboratories (NEIDL) and co-inventor of the TOP TB assay, stated, "Our ultrasensitive test is detecting Mycobacterium tuberculosis DNA in patients who are unlikely to be diagnosed with TB using current methods."

"These findings suggest we may be missing a significant burden of TB disease, particularly in older Americans and in patients with certain underlying conditions." — Dr. Edward C. Jones-López

The researchers emphasized that the findings are preliminary and require confirmation in larger, prospective multicenter studies.

Context and Technical Considerations

  • Global and U.S. Tuberculosis Burden: Tuberculosis remains the leading cause of death from an infectious disease worldwide. In the United States in 2023, tuberculosis was reported to have killed nearly 600 people and sickened more than 9,600. An estimated 13 million people in the U.S. carry a latent tuberculosis infection. Federal data indicates the number of new tuberculosis infections in the U.S. increased between 2021 and 2024.
  • Significance of DNA Detection: The study detected Mycobacterium tuberculosis DNA, not necessarily viable, culturable bacteria, in the patient samples. The researchers note that the clinical significance, infectiousness, and transmissibility associated with this DNA detection require further investigation.
  • Research Setting: The work was conducted at Boston University's NEIDL, a research facility equipped with Biosafety Level 3 and Biosafety Level 4 laboratories.