Analysis of prevalent Mycobacterium tuberculosis strains in the United Kingdom: detection, distribution and expansion of MIRU-VNTR profiles containing high numbers of isolates
Abstract number: P2054
Objectives: Universal DNA fingerprinting of M. tuberculosis strains has been utilised previously in population-based transmission studies and outbreak detection. This 4 year study describes the distribution and expansion of large clusters defined by MIRU-VNTR (Mycobacterial Interspersed Repetitive Units containing Variable Number Tandem Repeats) typing with the aim of identifying expanding clusters of M. tuberculosis earlier and directing public health control efforts and resources.
Methods: All M. tuberculosis isolates (n = 4,207) referred to the Health Protection Agency Midlands Regional Centre for Mycobacteriology from 200407 were typed by MIRU-VNTR using the 3 ETR and 12 MIRU loci on a WAVE(R) System. BioNumerics v5.1 was used to analyse the distribution and expansion of MIRU-VNTR clusters.
Results: Within the 4,207 isolates, 439 clustered MIRU-VNTR profiles containing 2,575 isolates were identified. Profiles containing paired isolates accounted for 196/439 (45%) of all clusters and 392/4,207 (9%) of all isolates. There were 127 (29%) clusters containing 5 isolates which contained 1,779 (43%) isolates. Clusters containing 217 isolates accounted for 415/439 (95%) of all clustered profiles and 1,1544/4,207 (37%) isolates with the largest 5% of all clusters containing 24 MIRU-VNTR profiles which varied from 19126 isolates in size and contained 1,027/4,207 (24%) of all isolates. In clusters that reached 5 isolates within 2 years, the first two strains were identified within an average of 4.04 months (95% CI: 3.114.97) of each other whereas the first two strains in clusters that did not reach 5 isolates within 2 years were identified within 12.12 months (95% CI: 10.9413.29) of each other.
Conclusion:M. tuberculosis MIRU-VNTR profiles normally occur in small-medium sized clusters with few profiles exhibiting rapid expansion rates to reach very high numbers of isolates. These expanding clusters more often have a second isolate appear more rapidly (4 versus 12 months), thus potentially allowing early identification and control.
|Session name:||Abstracts 20th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Vienna, Austria, 10 - 13 April 2010|
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