Background: Harris County (HC), Texas (TX) is the 3rd most populous county in the US and consistently has one of the highest tuberculosis (TB) rates in the US. Having a thorough understanding about the characteristics of the most common Mycobacterium tuberculosis (Mtb) genotyped clusters in this jurisdiction is urgently needed for local TB prevention programs.
Methods: Using data from the Centers for Disease Control and Prevention TB Genotyping Information Management System (TB GIMS), we described the demographic, laboratory and clinical characteristics for the 5 largest Mtb GENType, (a unique identifier based on spoligotype and 24-locus MIRU-VNTR), clusters in HC from 2009-2015. A large cluster was defined as a group of cases with the same genotype occurring in a jurisdiction and finite time, having more than 15 cases. Chi-square tests were used to test for an association between the 5 genotype clusters and specific characteristics of interest. A mixed model was used to analyze longitudinal factors associated with genotyped TB incidence in HC.
Results: In HC, 1637 of 2251 (72.7%) TB cases were genotyped and assigned a GENType, and 1058 different GENTypes were identified between 2009- 2015. The analyzed genotype clusters represent 14.2% (233/1637) of all genotyped TB cases: G00010 (n = 118), G00014 (n = 38), G00769 (n = 33), G01521 (n = 26), and G08964 (n = 18). There was no significant difference between the 5 GENType clusters in sputum smear or culture positivity (p >0.05). No MDR or XDR cases were found among 5 GENTypes analyzed. There was no significant difference on abnormal chest X-ray (p = 0.518), therapy resolution (p = 0.803) or having previously had TB (p = 0.706). Being male (p = 0.002), ethnicity (p <0.001), homelessness (p <0.001), excessive alcohol use (p = 0.002), and US birth (p = 0.004) were significantly associated with the 5 GENTypes. No factors were significantly associated with the incidence of genotyped TB cases longitudinally among the 5 GENTypes in HC.
Conclusion: Of the >1000 distinct GENTypes identified in HC, 5 large Mtb GENType clusters were seen between 2009 and 2015. The genotypes were seen primarily in those born in the US despite the large foreign born population residing in HC.
Distribution of TB GENType G00010 in Harris County from 2009-2015
L. Teeter, None
E. A. Graviss, None