Notes from the Field: Use of Genotyping to Disprove a Presumed Outbreak of Mycobacterium tuberculosis - Los Angeles County, 2013-2014.

Baker BJ, Poonja S, Mesrobian M, Lai A, Hwang S.

Abstract

In early 2013, the Los Angeles County Department of Public Health learned of two patients diagnosed with tuberculosis (TB) who had received care at the same outpatient health care facility (facility A). Facility A is a center for infusions of chemotherapeutic and biologic agents and serves a large number of immunocompromised persons who were potentially exposed to infectious TB. If infected, immunocompromised persons are at elevated risk for progression to TB disease. The two patients (patient A and patient B) both had pulmonary TB, with acid-fast bacilli found on sputum-smear microscopy, and had visited facility A multiple times during their infectious periods. Despite initial concerns that these two cases could be the result of person-to-person transmission at facility A, genotyping of the Mycobacterium tuberculosis isolates from these two patients showed that they were infected with unrelated strains.