Abstract
BACKGROUND: Monoresistance to rifamycins necessitates longer and more toxic regimens for tuberculosis (TB). We examined characteristics and mortality associated with rifampin-monoresistant (RMR) TB in the United States. METHODS: We analyzed Mycobacterium tuberculosis culture-positive cases reported to the National TB Surveillance System (excluding California) between 1998 and 2014. We defined RMR TB found on initial drug susceptibility testing and possible acquired rifampin-resistant (ARR) TB. We assessed temporal trends in RMR TB. For both classifications of rifampin resistance, we calculated adjusted risk ratios (adjRRs) and 95% confidence intervals (CIs) for characteristics associated with mortality when compared with drug-susceptible TB in multivariable models using backward selection. RESULTS: Of 180 329 TB cases, 126 431 (70%) were eligible for analysis, with 359 (0.28%) of eligible cases reported as RMR. The percentage of RMR TB cases with HIV declined 4% annually between 1998 and 2014. Persons with HIV and prior TB were more likely to have RMR TB (adjRR, 25.9; 95% CI, 17.6-38.1), as were persons with HIV and no prior TB (adjRR, 3.1; 95% CI, 2.4-4.1) vs those without either characteristic, controlling for other statistically significant variables. RMR cases had greater mortality (adjRR, 1.4; 95% CI, 1.04-1.8), controlling for HIV and other variables. Persons with HIV had greater risk of ARR than persons without HIV (adjRR, 9.6; 95% CI, 6.9-13.3), and ARR was also associated with increased mortality, controlling for HIV and other variables. CONCLUSIONS: All forms of rifampin resistance were positively associated with HIV infection and increased mortality.