Compilation of 10 Years of MIRU-VNTR Data: Canadian National Tuberculosis Laboratory's Experience

Abstract

Tuberculosis is a significant cause of morbidity worldwide and is a priority at the provincial and federal levels in Canada. It is known that tuberculosis transmission networks are complex and span many years as well as different jurisdictions and countries. MIRU-VNTR is a universal tuberculosis genotyping method that utilizes a 24-loci pattern and it has shown promise in identifying inter and intrajurisdictional clusters within Canada. MIRU-VNTR data collected over 10 years from the National Reference Centre for Mycobacteriology (NRCM) were analyzed in this study. Some clusters were unique to a single province/territory, while others spanned multiple provinces and/or territories in Canada. The use of a universal laboratory test can enhance contact tracing, provide geographical information on circulating genotypes, and hence, aid in tuberculosis investigation by public health. The housing of all data on one platform, technical ease of the method, easy exchange of data between jurisdictions, and strong collaboration with laboratories and surveillance units at the provincial and federal levels have the potential to identify possible outbreaks in real time.

Figure 1

Number of MIRU-VNTR tests reported by the NRCM to various Canadian provinces over the period of 10 years between 2008 and 2017 NB, New Brunswick; NS, Nova Scotia including Prince Edward Island; NL, Newfoundland. Labrador y = number of MIRU-VNTR tests reported by the NRCM; x = year of submission.

Figure 2

MIRU-VNTR clusters in the NRCM database: data shown are for “two isolates per cluster” to “≥10 isolates per cluster.” A total number of clusters in the database that had identical MIRU-VNTR are also shown in figure. X = number of MIRU-VNTR matches (a cluster can be comprised of two to ≥10 isolates); Y = number of clusters.

Figure 3

Distribution of six largest MIRU-VNTR clusters that contain more than 100 isolates each, shown per Canadian province or territory. BC, British Columbia; AB, Alberta; SK, Saskatchewan; MB, Manitoba; NT, Northwest Territories; NU, Nunavut; QC, Quebec; NS, Nova Scotia including Prince Edward Island isolates; NL, Newfoundland.

Figure 4

Distribution of the largest six MIRU-VNTR clusters in national laboratory, Canada.

Figure 5

A dendrogram of all MIRU-VNTR patterns and clusters in the NRCM database^∗. ^∗ON (Ontario) submissions reflect submission by parks Canada and not ON provincial TB laboratory. The distance was calculated using the UPGMA clustering algorithm, with different colors representing different provinces or territories. The figure is showing that most patterns are not unique to one jurisdiction. AB, Alberta; BC, British Columbia; MB, Manitoba; INT, International; NT, Northwest Territories; NU, Nunavut; QC, Quebec; NS, Nova Scotia including Prince Edward Island cases; NL, Newfoundland; SK, Saskatchewan.