Evaluation of 24 locus MIRU-VNTR genotyping of Mycobacterium tuberculosis isolates in Canada
Received 14 September 2009; received in revised form 5 December 2009; accepted 9 December 2009. published online 08 January 2010.
summary
The current gold standard for Mycobacterium tuberculosis complex (MTBC) genotyping is insertion sequence (IS) 6110 restriction fragment length polymorphism (RFLP) as it provides the highest discriminatory power of all available MTBC genotyping methods. However, RFLP is labour intensive and the interpretation of data from this method can be susceptible to errors. In 2001 a rapid, reproducible variable number of tandem repeat (VNTR) based typing method using 12 mycobacterial interspersed repetitive units (MIRU) was developed. Despite this advancement, this method lacked the discriminatory power of IS6110-RFLP. More recently a set of 24 MIRU-VNTR loci was reported to have greater discriminatory power than the original 12 locus system and may exceed that of RFLP when combined with spoligotyping. We compared the 24 locus method to the 12 locus method in order to improve surveillance of tuberculosis in Canada.
A random sample of 650 MTBC isolates from British Columbia, Saskatchewan, Manitoba and Quebec Canada was genotyped using the 24 MIRU loci. Comparison of the data for the 12 and 24 MIRU loci showed an increase of the Hunter–Gaston discriminatory index (HGDI) from 0.895 (12 loci) to 0.920 (24 loci). The implementation of the 24 locus MIRU-VNTR methods offers improvement in discriminatory power over the traditional 12 locus method. For long-term surveillance of MTBC within Canada, the use of 24 MIRU-VNTR loci will provide rapid, highly discriminatory molecular epidemiology information.
bUniversity of Manitoba, 730 William Avenue, Winnipeg, Manitoba, Canada
cDepartment of Clinical Microbiology, Health Sciences Centre, Winnipeg, Manitoba, Canada
dSaskatchewan Disease Control Laboratory, 3211 Albert Street, Regina, Saskatchewan, Canada
eLaboratoire de santé publique du Québec, Institut national de santé publique du Québec, 20045, chemin Sainte-Marie, Sainte-Anne-de-Bellevue, Québec, Canada
fTB/Mycobacteriology Program, B.C. Centre for Disease Control, 655 West 12th Avenue, Vancouver, British Columbia, Canada
gDepartment of Pathology and Laboratory Medicine, University of British Columbia, Vancouver, British Columbia, Canada
Corresponding author at: National Reference Centre for Mycobacteriology, National Microbiology Laboratory, 1015 Arlington Street, Winnipeg, Manitoba R3E 3R2, Canada. Tel.: +1 204 789 6081; fax: +1 204 789 2036.
ABSTRACT