Molecular Characteristics of Mycobacterium tuberculosis Strains Isolated from Cutaneous Tuberculosis Patients in China

Abstract

Cutaneous tuberculosis (CTB) is probably underreported due to difficulties in detection and diagnosis. To address this issue, genotypes of Mycobacterium tuberculosis strains isolated from 30 patients with CTB were mapped at multiple loci, namely, RD105 deletions, spacer oligonucleotides, and Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats (MIRU-VNTRs). Fifty-eight strains of pulmonary tuberculosis (PTB) were mapped as experimental controls. Drug resistance-associated gene mutations were determined by amplicon sequencing of target regions within 7 genes. Beijing family isolates were the most prevalent strains in CTB and PTB. MIRU-VNTR typing separated the Beijing strains from the non-Beijing strains, and the majority of CTB could be separated from PTB counterparts. Drug resistance determining regions showed only one CTB strain expressing isomazid resistance. Thus, while the CTB strains belonged to the same phylogenetic lineages and sub-lineages as the PTB strains, they differed at the level of several MIRU-VNTRs and in the proportion of drug resistance.

Adapting Clofazimine for Treatment of Cutaneous Tuberculosis by Using Self-Double-Emulsifying Drug Delivery Systems

“…According to the 2018 WHO global TB statement, treatment is only effective in 55% of individuals that contracted MDR-TB, and is only effective in 34% of XDR-TB patients [ 25 , 35 ]. The presence of MDR-TB and XDR-TB furthermore enhance the occurrence of extra-pulmonary TB infections [ 52 ]. Therefore, treatment is even more complicated as 5% of all new TB cases are considered multi-drug resistant, with the global estimate being that 3.3% of first time TB cases and 20.5% of previously treated TB patients display MDR-TB [ 32 , 38 ].…”

Cutaneous Tuberculosis: Clinicopathologic Arrays and Diagnostic Challenges

“…The major molecular typing methods—Spoligotyping, MIRU-VNTR (Mycobacterial Interspersed Repetitive Unit-Variable Number Tandem Repeats), and RFLP—detect Mycobacterium tuberculosis , DNA, or RNA in clinical specimens by in vitro nucleic acid amplifications, empowering investigations into epidemiology, transmission, and PTB outbreaks [ 56 ]. The clinical applicability testing of these genotyping techniques was also accessed in the patients with cutaneous tuberculosis in China by Ziang et al, 2017, with augmented sensitivity and specificity [ 57 ].…”

“…Spoligotyping—commonly used to differentiate Mycobacterium tuberculosis complex strain—is based on polymorphisms of the chromosomal direct repeat (DR) locus, which contains a variable number of short DRs interspersed with nonrepetitive spacers [ 56 , 57 ].…”

“…Lately, the International consortium has proposed MIRU-VNTR as a standardized genotyping scheme, with 15- and 24-locus sets proven to have ample discriminatory power for tracing transmission and investigating the phylogenetics of tuberculosis [ 57 ].…”