Genotypic characterization and historical perspective of Mycobacterium tuberculosis among older and younger Finns, 2008–2011

Abstract

The Mycobacterium tuberculosis genotypes obtained from elderly Finns were assessed and compared with those obtained from younger Finns to comprehend the epidemiology of tuberculosis (TB) in Finland. From 2008 to 2011, a total of 1021 M. tuberculosis isolates were characterized by spoligotyping and 15-locus mycobacterial interspersed repetitive units-variable number tandem repeat typing. In total, 733 Finnish-born cases were included in the study, of which 466 (64%) were born before 1945 (older Finns). Of these, 63 (14%) shared an M. tuberculosis genotype with foreign-born or younger Finnish cases (born after 1945), and 59 (13%) shared a genotype with older Finnish cases. Eighty-five per cent had a unique genotypic profile while 70% belonged to T or Haarlem families, suggesting that ongoing transmission is infrequent among young and elderly Finns. Simultaneous reactivation of TB among older Finns was the most likely cause for clustering. As most isolates belonged to Haarlem or T, Finland was most likely affected by a similar TB epidemic at the beginning of the twentieth century as that seen in Sweden and Norway. Younger Finns were significantly more likely to be clustered (56% versus 27%, p<0.001), have pulmonary TB (87% versus 71%, p<0.001) and to be sputum smear positive (57% versus 48%, p<0.05) indicating that the risk of TB transmission from younger Finns is likely to be larger than from older Finns. The M. tuberculosis isolates from elderly Finns were associated with dominant lineages of the early twentieth century and differed from the heterogeneous lineages found among younger TB patients. Additionally, younger TB patients were more likely to transmit TB than elderly Finns.

Characterization of Mycobacterium tuberculosis isolates from Hebei, China: genotypes and drug susceptibility phenotypes

“…Easy operation, digital database and high discriminatory power make it an alternative method for RFLP [ 9 ]. Moreover, the combined application of MIRU-VNTR and spoligotyping is increasingly common in MTB molecular epidemiology research [ 10 , 11 ].…”

Phylogenetic relationships of Mycobacterium tuberculosis isolates in Poland: The emergence of Beijing genotype among multidrug-resistant cases

“…It can be only speculated that infections with Haarlem isolates are associated with better treatment outcomes, and thus are easier to eradicate, if low-transmissible ( Reiling et al., 2013 ). Haarlem is a “European” genotype with a clear geographically increasing East-to-West gradient ( Smit et al., 2014 ; Pichat et al., 2016 ; Vluggen et al., 2017 ; Pole et al., 2020 ), and low prevalence in FSU countries.…”

Tuberculosis contact investigation results among paediatric contacts in low-incidence settings in Finland

“…Thus, optimally, all exposed children should have been BCG vaccinated. In Finland, majority of TB cases still occur among the older indigenous population, and TB exposure from grandparents was substantial [ 26 ]. Most of the exposed children under 5 years of age with a grandparent as an index case were non-BCG-vaccinated suggesting that this risk group of grandchildren is not comprehensively captured under the current selective BCG policy.…”