Ji Young Kang1, Jung Hur1, Shinyoung Kim2, Sanghoon Jeon3, Jaeha Lee4, Youn Jeong Kim1, Seok Chan Kim1, Yeon Joon Park5, Young Kyoon Kim1, Hwa Sik Moon6. 1. Department of Internal Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Republic of Korea. 2. Department of Internal Medicine, College of Medicine, St. Vincent's Hospital, The Catholic University of Korea, Republic of Korea. 3. Department of Internal Medicine, Inha University School of Medicine, Incheon, Republic of Korea. 4. Department of Internal Medicine, Inje University College of Medicine, Haeundae Paik Hospital, Busan, Republic of Korea. 5. Deparment of Laboratory Medicine, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea. 6. Department of Internal Medicine, St. Paul's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.
Abstract
BACKGROUND: The widespread use of molecular, genotypic drug susceptibility tests (DSTs) for antituberculosis (anti-TB) drugs has led to the dilemma of interpreting discordant results between genotypic and conventional, phenotypic DSTs. We investigated the clinical characteristics, including treatment patterns and outcomes, of TB patients with a genotype-phenotype discrepancy in susceptibility to isoniazid (INH) or rifampicin (RIF). METHODS: We retrospectively reviewed the medical records of TB patients who had results for 2 DSTs (genotypic method, MTBDRplus test for INH and RIF, and phenotypic method) treated between August 2010 and October 2016 in a tertiary university hospital. RESULTS: Among 1,069 TB patients, 63 (5.9%) had discrepant results for the 2 DSTs. Of the 57 multidrug-resistant (MDR) TB cases diagnosed by either DST, 18 (31.6%) showed discordant results for INH or RIF. The most frequent pattern of discordance was genotypic susceptibility with phenotypic resistance to INH. RIF-discordant subjects with genotypic resistance were more likely to have been exposed previously to anti-TB drugs and to have an MDR TB diagnosis and concurrent INH resistance. Forty-five of the 54 patients managed in our hospital (83.3%) had a favorable outcome with a mean treatment duration of 14.0 months. Ten of the 16 INH-discrepant patients with a genotypic mutation continued taking INH, but more than half patients in the RIF-discrepant group (8/14) with a genotypic mutation discontinued taking RIF. CONCLUSIONS: Despite the low frequency, discordant results were obtained between the genotypic and phenotypic DSTs for INH or RIF, especially for patients with MDR TB or INH resistance. Furthermore, it seemed that RIF discrepancy with a genotypic mutation might have a greater impact on the clinical outcome than INH discrepancy.
BACKGROUND: The widespread use of molecular, genotypic drug susceptibility tests (DSTs) for antituberculosis (anti-TB) drugs has led to the dilemma of interpreting discordant results between genotypic and conventional, phenotypic DSTs. We investigated the clinical characteristics, including treatment patterns and outcomes, of TB patients with a genotype-phenotype discrepancy in susceptibility to isoniazid (INH) or rifampicin (RIF). METHODS: We retrospectively reviewed the medical records of TB patients who had results for 2 DSTs (genotypic method, MTBDRplus test for INH and RIF, and phenotypic method) treated between August 2010 and October 2016 in a tertiary university hospital. RESULTS: Among 1,069 TB patients, 63 (5.9%) had discrepant results for the 2 DSTs. Of the 57 multidrug-resistant (MDR) TB cases diagnosed by either DST, 18 (31.6%) showed discordant results for INH or RIF. The most frequent pattern of discordance was genotypic susceptibility with phenotypic resistance to INH. RIF-discordant subjects with genotypic resistance were more likely to have been exposed previously to anti-TB drugs and to have an MDR TB diagnosis and concurrent INH resistance. Forty-five of the 54 patients managed in our hospital (83.3%) had a favorable outcome with a mean treatment duration of 14.0 months. Ten of the 16 INH-discrepant patients with a genotypic mutation continued taking INH, but more than half patients in the RIF-discrepant group (8/14) with a genotypic mutation discontinued taking RIF. CONCLUSIONS: Despite the low frequency, discordant results were obtained between the genotypic and phenotypic DSTs for INH or RIF, especially for patients with MDR TB or INH resistance. Furthermore, it seemed that RIF discrepancy with a genotypic mutation might have a greater impact on the clinical outcome than INH discrepancy.
Entities:
Keywords:
Drug resistance; discrepancy; isoniazid; mycobacterium tuberculosis; rifampicin
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