Outbreak of Drug-Resistant Mycobacterium tuberculosis Among Homeless People in Atlanta, Georgia, 2008-2015

Abstract

Objectives: Our objective was to describe and determine the factors contributing to a recent drug-resistant tuberculosis (TB) outbreak in Georgia.

Methods: We defined an outbreak case as TB diagnosed from March 2008 through December 2015 in a person residing in Georgia at the time of diagnosis and for whom (1) the genotype of the Mycobacterium tuberculosis isolate was consistent with the outbreak strain or (2) TB was diagnosed clinically without a genotyped isolate available and connections were established to another outbreak-associated patient. To determine factors contributing to transmission, we interviewed patients and reviewed health records, homeless facility overnight rosters, and local jail booking records. We also assessed infection control measures in the 6 homeless facilities involved in the outbreak.

Results: Of 110 outbreak cases in Georgia, 86 (78%) were culture confirmed and isoniazid resistant, 41 (37%) occurred in people with human immunodeficiency virus coinfection (8 of whom were receiving antiretroviral treatment at the time of TB diagnosis), and 10 (9%) resulted in TB-related deaths. All but 8 outbreak-associated patients had stayed overnight or volunteered extensively in a homeless facility; all these facilities lacked infection control measures. At least 9 and up to 36 TB cases outside Georgia could be linked to this outbreak.

Conclusions: This article highlights the ongoing potential for long-lasting and far-reaching TB outbreaks, particularly among populations with untreated human immunodeficiency virus infection, mental illness, substance abuse, and homelessness. To prevent and control TB outbreaks, health departments should work with overnight homeless facilities to implement infection control measures and maintain searchable overnight rosters.

Keywords: disease outbreaks; drug resistance; homeless people; infection control; tuberculosis.

Figure 1.

Distribution of 110 tuberculosis (TB) outbreak cases in Georgia, by year of case report, January 2008 to December 2015. The 110 cases include 84 genotyped TB outbreak-associated cases in Georgia and 26 epidemiologically linked TB cases in Georgia without genotype results. “A” indicates that the Mycobacterium tuberculosis isolate was not sent for genotyping for a patient with recurrent culture-confirmed TB and previous genotype-confirmed outbreak case. “B” indicates that the M tuberculosis isolate had unresolved and mixed genotyping results for a patient with culture-confirmed TB. Abbreviation: Q, quarter.

Figure 2.

Geographic distribution of 120 tuberculosis (TB) cases with genotype consistent with the Georgia outbreak strain, United States, March 2008 to December 2015. The 120 cases include 84 genotyped TB outbreak-associated cases in Georgia and 36 genotyped TB cases outside of Georgia in which isolate genotype matched that of the Georgia outbreak cases.