View Abstract

A6958 - Transmission of Acquired Rifampin Resistant Tuberculosis Among Three Sisters in Texas
Author Block: N. Keaton1, A. Vasquez2; 1Internl Medicine, San Antonio Uniformed Services Health Education Consortium, San Antonio, TX, United States, 2Infectious Disease, Texas Center for Infectious Diseases, San Antonio, TX, United States.
Introduction Rifampin is the most effective drug available for treatment of tuberculosis. Only the new but very expensive drug, bedaquiline, approaches the effectiveness of rifampin for killing Mycobacterium tuberculosis (MTB) and preventing relapse. Rifampin resistant tuberculosis (RR-TB) is a surrogate marker of Multi-Drug Resistant Tuberculosis (MDR-TB) and rifampin monoresistance is associated with equally poor outcomes. Rapid diagnosis of RR-TB improves patient outcomes and decreases transmission. The World Health Organization recommends using Xpert MTB/RIF (Xpert) nucleic acid amplification testing as the initial diagnostic test in adults suspected of having MDR-TB. Xpert is widely used in Texas for early identification of MTB disease and to screen for rifampin resistance. The Centers for Disease Control recommends confirmation with DNA sequence-based testing and phenotypic susceptibilities when Xpert detects rifampin resistance. Case Description We describe transmission of acquired rifampin resistant tuberculosis from a patient to her two sisters. All three sisters had a history of TB, previously treated in their birth country in their birth country. The index case had recurrent disease, mistakenly treated as LTBI with rifampin monotherapy and acquired rifampin monoresistance. Contact investigation at that time showed her sisters to have a normal CXR and no symptoms. The index patient relapsed with susceptible TB. Repeat contact investigation now identified both sisters with active TB. Xpert testing, which was confirmed by molecular and phenotypic testing, showed RR-TB in one and susceptible TB in the other sister. TB genotype was identical for all three sisters. Conclusions This case demonstrates the importance of appropriate initial TB therapy to prevent relapse and acquisition of drug resistant TB. Screening with Xpert helps ensure initiation of appropriate therapy in patients at risk for resistant TB. Despite identification of drug susceptible TB, all three were treated as RR-TB due to concern for undetectable rifampin resistance mycobacteria in a heterogeneous populations of MTB.