A multicenter evaluation of a biochip system for detection of rifampin and isoniozid resistance in clinic strains of Mycobacterium tuberculosis / 中华检验医学杂志

ABSTRACT

Objective To evaluate a rapid biochip system for the determination of muhidrugresistant tuberculosis (MDR-TB) in Mycobacterium tuberculosis isolates. MethodsA total of 1 186 clinical strains, including 800 rifampin (RFP) resistant isolates, 797 isoniozid (INH)resistant isolates, 791 MDR-TB and 380 susceptible strains, were selected from Beijing Chest Hospital, Shanghai Pulmonary Hospital and Guangzhou Chest Hospital respectively using stratified sampling method. Biochips were used to detect loci of rpoB 511 (T→C), 513 (A→C, C→A), 516 (G→T, A→T, A→G) , 526 (C→T, C→G, A→T, A→G), 531 (C→T, C→G), 533 (T→C), katG 315 ( G→C, G→A) and inhA -15 (C→T). Absolute concentration drug susceptibility test of RFP and INH were performed to serve as the gold standard to calculate susceptibility, specificity and overall concordance of biochip test. All polymerase chain reaction (PCR) products were sequenced to confirm the mutations. ResultsThe concordances between the biochip system and absolute concentration drug susceptibility test were 93.7％ ( 1 108/1 183 ) for RFP, 83. 8％(994/1 186) for INH and 82.4％ (975/1 183) for MDR-TB. Compared with absolute concentration drug susceptibility test, the biochip method displayed a sensitivity of 92. 0％ (733/797) and 77. 4％ (617/797)and a specificity of 97. 2％ (375/386) and 96. 9％ (377/389) for RIF and INH, respectively. For MDR-TB, the biochip system reached a sensitivity of 74. 6％ ( 588/788 ) and a specificity of 98.0％ ( 387/395 ).Among rpoB mutants, mutations were mostly detected at codon 531[64. 5％ (480/744)]. In stains with mutations in katG or inhA, 77.4％ ( 487/629 ) had mutation at codon 315 ( TCG ) of katG only. The sequencing results had a high concordance with that of the biochip method. There were slight differences in 5 strains, among which one strain was detected by biochip as katG 315(G→C) mutant, but was identified by sequencing as wild type, and mutation types other than those detected by the biochip were confirmed in the other 4 strains by sequencing. Conclusion This biochip system is adapted for extensive application in clinical diagnosis, as it allows fast and reliable detection of resistance to isoniazid and rifampin in tuberculosis clinical isolates.