Drug resistance for Mycobacterium tuberculosis testing in China

Author(s): Kadri Altraja

Background Despite the fact that Mycobacterium TB phenotypic drug susceptibility testing (DST) can take up to 6-8 weeks, nothing is known about how drug susceptibility is changed over this time [1]. Methods Using 359 patients with pulmonary tuberculosis who had baseline DST results from a Mtb isolate collected at the time of TB diagnosis and follow-up DST results from a Mtb isolate collected when baseline DST results were available between 2013 and 2018, we conducted a prospective cohort study to examine the development of drug resistance during turnaround time [2]. The distinction between acquired drug resistance, exogenous reinfection, and mixed infection was determined using whole-genome sequencing [3]. 116 (32.3%) of the participants in the study developed DR to four first-line medications during the TAT for DST. 21 pairings of the 116 pairs of isolates included in the WGS were categorised with changes in single nucleotide polymorphisms smaller than were classed as acquired drug resistance [4]. Four couples were identified as having mixed infections because they showed small variations in linked genotypes and had intermediate SNP differences [5]. High SNP differences in the remaining 91 pairings were indicative of exogenous reinfection [6].