Island populations that are relatively small and remote are inherently interesting from an infectious disease evolution perspective. Geographic isolation and sparse populations can limit transmission and enhance independent evolutionary processes. This can provide unique insights into the dynamics of host-pathogen interaction. The Faroe Islands (population ~50,000) includes 17 inhabited islands located in the North Atlantic between Iceland, Scotland and Norway. With the exception of Torshavn (population ~20,000), only eight communities have >1,000 residents.
Isolates from pharyngitis or asymptomatic carriage (n = 125, collected in 2009-2010), or invasive infections (n = 37, collecrted between 1998 and 2016) were studied. Genomes were sequenced using Illumina technology and analyzed using common bioinformatic methods.
Strains were sequenced to ~150 fold-coverage. Among the noninvasive isolates, 11 emm-types (and 11 multi-locus sequence types, MLSTs) were identified, the majority (>90%) being emm1, 2, 4, 6, 22, and 89. Thirteen emm-types (and 15 MLSTs) were identified among the invasive strains, most (>70%) being emm1, 3, 4, 12, 28, and 89. These emm-types are common in other developed countries of North America and Europe. Antibiotic resistance frequency was low (<7%) and was largely limited to tetracycline resistance in emm22 noninvasive isolates. Genome sequences were compared with and are presented relative to isolates of the same emm-types collected from other North American and European countries.
Our study is the largest genomic analysis of a bacterial pathogen causing infections in the Faroe Islands. The resulting data provided new information about S. pyogenes infections in these islands.