Genomic Diversity of Mycobacterium tuberculosis Complex Strains in Cantabria (Spain), a Moderate TB Incidence Setting.
BACKGROUND
Tuberculosis (TB) control strategies are focused mainly on prevention, early diagnosis, compliance to treatment and contact tracing. The objectives of this study were to explore the frequency and risk factors of recent transmission of clinical isolates of Mycobacterium tuberculosis complex (MTBC) in Cantabria in Northern Spain from 2012 through 2013 and to analyze their clonal complexity for better understanding of the transmission dynamics in a moderate TB incidence setting.


METHODS
DNA from 85 out of 87 isolates from bacteriologically confirmed cases of MTBC infection were extracted directly from frozen stocks and genotyped using the mycobacterial interspersed repetitive units-variable number tandem repeat (MIRU-VNTR) method. The MIRU-VNTRplus database tool was used to identify clusters and lineages and to build a neighbor joining (NJ) phylogenetic tree. In addition, data were compared to the SITVIT2 database at the Pasteur Institute of Guadeloupe.


RESULTS
The rate of recent transmission was calculated to 24%. Clustering was associated with being Spanish-born. A high prevalence of isolates of the Euro-American lineage was found. In addition, MIRU-VNTR profiles of the studied isolates corresponded to previously found MIRU-VNTR types in other countries, including Spain, Belgium, Great Britain, USA, Croatia, South Africa and The Netherlands. Six of the strains analyzed represented clonal variants.


CONCLUSIONS
Transmission of MTBC is well controlled in Cantabria. The majority of TB patients were born in Spain. The population structure of MTBC in Cantabria has a low diversity of major clonal lineages with the Euro-American lineage predominating.
Service of Microbiology, University Hospital Marqués de Valdecilla, Santander, Spain.|International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.|Valdecilla Biomedical Research Institute (IDIVAL), Santander, Spain.
Inmaculada C
IC
Pérez Del Molino Bernal
International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
Troels
T
Lillebaek
International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
Mathias K
MK
Pedersen
Service of Microbiology, University Hospital Marqués de Valdecilla, Santander, Spain.|Valdecilla Biomedical Research Institute (IDIVAL), Santander, Spain.|Department of Molecular Biology, School of Medicine, University of Cantabria, Santander, Spain.
Luis
L
Martinez-Martinez
International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
Dorte B
DB
Folkvardsen
Service of Microbiology, University Hospital Marqués de Valdecilla, Santander, Spain.|Valdecilla Biomedical Research Institute (IDIVAL), Santander, Spain.|Department of Molecular Biology, School of Medicine, University of Cantabria, Santander, Spain.
Jesús
J
Agüero
International Reference Laboratory of Mycobacteriology, Statens Serum Institut, Copenhagen, Denmark.
E Michael
EM
Rasmussen
D000328:Adult; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D018598:Minisatellite Repeats / Q000235:genetics; D017720:Molecular Epidemiology; D009169:Mycobacterium tuberculosis / Q000235:genetics* / Q000472:pathogenicity; D010802:Phylogeny; D013030:Spain; D014376:Tuberculosis / Q000453:epidemiology* / Q000235:genetics* / Q000382:microbiology