Contact Investigations Around Mycobacterium tuberculosis Patients Without Positive Respiratory Culture

To evaluate the yield and effectiveness of contact investigations conducted around potentially infectious tuberculosis (TB) patients with no positive respiratory culture for Mycobacterium tuberculosis in New York City (NYC).

All TB patients without a positive respiratory culture from 2003 to 2012 were extracted from the NYC TB registry, and all patients eligible for contact investigation and their contacts were evaluated. Patients without a positive respiratory culture were defined as eligible for contact investigation if they had a respiratory nucleic acid amplification result positive for M tuberculosis, a cavitary chest radiograph, or a positive respiratory acid-fast bacilli smear.

NYC, New York.

To evaluate the yield of the investigations, the number of contacts identified and the outcome of testing was quantified. Potential transmission was defined on the basis of whether active TB patients were detected among the contacts and if a contact had a TB test conversion.

From 2003 to 2012, there were 2191 TB patients without a positive respiratory culture in NYC, 374 (17%) of which were considered eligible for contact investigation. A total of 11 096 contacts were identified around 300 (80%) eligible patients, 136 of whom had a diagnosis of TB infection; of those with TB infection who initiated preventive treatment, 66% completed treatment. Potential transmission was identified around 14 patients, with the identification of 2 additional cases of active TB and 15 contacts with TB infection test conversion.

Conducting contact investigations around patients without a positive respiratory culture yielded evidence of possible transmission and led to the identification and treatment of new TB cases and those with TB infection. These findings suggest that these investigations should be conducted in settings where resources permit.