Evaluation of 24 locus MIRU-VNTR genotyping of Mycobacterium tuberculosis isolates in Canada.
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.
Christianson
Sara
S
National Microbiology Laboratory, 1015 Arlington Avenue, Winnipeg, Manitoba R3E 3R2, Canada. sara_christianson@phac-aspc.gc.ca <sara_christianson@phac-aspc.gc.ca>
Wolfe
Joyce
J
Orr
Pamela
P
Karlowsky
James
J
Levett
Paul N
PN
Horsman
Greg B
GB
Thibert
Louise
L
Tang
Patrick
P
Sharma
Meenu K
MK
D015373:Bacterial Typing Techniques; D002170:Canada / Q000453:epidemiology; D004269:DNA, Bacterial / Q000235:genetics*; D005838:Genotype; D006801:Humans; D018598:Minisatellite Repeats; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000302:isolation & purification; D012150:Polymorphism, Restriction Fragment Length; D015203:Reproducibility of Results; D014376:Tuberculosis / Q000453:epidemiology / Q000235:genetics*
D004269:DNA, Bacterial