Molecular Typing of Mycobacterium Tuberculosis Complex by 24-Locus Based MIRU-VNTR Typing in Conjunction with Spoligotyping to Assess Genetic Diversity of Strains Circulating in Morocco

Abstract

BackgroundStandard 24-locus Mycobacterial Interspersed Repetitive Unit Variable Number Tandem Repeat (MIRU-VNTR) typing allows to get an improved resolution power for tracing TB transmission and predicting different strain (sub) lineages in a community.MethodologyDuring 2010–2012, a total of 168 Mycobacterium tuberculosis Complex (MTBC) isolates were collected by cluster sampling from 10 different Moroccan cities, and centralized by the National Reference Laboratory of Tuberculosis over the study period. All isolates were genotyped using spoligotyping, and a subset of 75 was genotyped using 24-locus based MIRU-VNTR typing, followed by first line drug susceptibility testing. Corresponding strain lineages were predicted using MIRU-VNTRplus database.Principal FindingsSpoligotyping resulted in 137 isolates in 18 clusters (2–50 isolates per cluster: clustering rate of 81.54%) corresponding to a SIT number in the SITVIT database, while 31(18.45%) patterns were unique of which 10 were labelled as “unknown” according to the same database. The most prevalent spoligotype family was LAM; (n = 81 or 48.24% of isolates, dominated by SIT42, n = 49), followed by Haarlem (23.80%), T superfamily (15.47%), >Beijing (2.97%), > U clade (2.38%) and S clade (1.19%). Subsequent 24-Locus MIRU-VNTR typing identified 64 unique types and 11 isolates in 5 clusters (2 to 3isolates per cluster), substantially reducing clusters defined by spoligotyping only. The single cluster of three isolates corresponded to two previously treated MDR-TB cases and one new MDR-TB case known to be contact a same index case and belonging to a same family, albeit residing in 3 different administrative regions. MIRU-VNTR loci 4052, 802, 2996, 2163b, 3690, 1955, 424, 2531, 2401 and 960 were highly discriminative in our setting (HGDI >0.6).Conclusions24-locus MIRU-VNTR typing can substantially improve the resolution of large clusters initially defined by spoligotyping alone and predominating in Morocco, and could therefore be used to better study tuberculosis transmission in a population-based, multi-year sample context.

Genetic diversity of multidrug‐resistant Mycobacterium tuberculosis strains isolated from tuberculosis patients in Iran using MIRU‐VNTR technique

“…These are the loci previously reported as the most discriminatory in a number of other settings in Iran and elsewhere [10,25–29]. Although the system based on 12 loci is most widely used among different sets of MIRU‐VNTR loci, however, the discriminatory of present study was lower than those of other studies, in which the investigators reported the higher discriminatory yielded by 24 loci MIRU‐VNTR on their isolates [7,13].…”

“…Molecular typing of MTBC is a powerful adjunct to TB control to monitor the disease transmission, and to detect or confirm outbreaks [7]. In last decades, several genotyping methods have been used for studying of molecular epidemiology of MTB.…”

Association between genotype and drug resistance profiles of Mycobacterium tuberculosis strains circulating in China in a national drug resistance survey

“…Accordingly, these regions with a high prevalence of Beijing B0/W148 strains were also reported to have a heavy MDR-TB burden, indicating this closely related group of strains appears to be able to successfully generate resistance to the current standard therapy while they remain transmissible in certain settings [1,46]. Searching through literature, we found these epidemic strains in China were previously also reported in Europe and North Africa but at a low prevalence, suggesting these clusters are globally wide spread but with different levels of adaptation in different areas [47,48]. …”

Molecular Epidemiology of Tuberculosis and Transmission Dynamics of Mycobacterium tuberculosis Complex in Morocco

“…Overall, four studies conducted using spoligotyping were included in this review. First, Brudey et al [12] Much later, the study conducted by Bouklata et al [15] has permitted to track and monitor the extent of genetic diversity of MTB strains. Within this context, a total of 168 MTBC isolates were collected during 2010-2012 from 10 different Moroccan cities, and subjected to spoligotyping.…”