TY - JOUR
T1 - Genomic Characteristics Behind the Spread of Bacteremic Group A Streptococcus Type emm89 in Finland, 2004-2014
AU - Latronico, Francesca
AU - Nasser, Waleed
AU - Puhakainen, Kai
AU - Ollgren, Jukka
AU - Hyyryläinen, Hanne-Leena
AU - Beres, Stephen B
AU - Lyytikäinen, Outi
AU - Jalava, Jari
AU - Musser, James M
AU - Vuopio, Jaana
N1 - © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America.
PY - 2016/12/15
Y1 - 2016/12/15
N2 - BACKGROUND: Many countries worldwide have reported increasing numbers of emm89 group A Streptococcus (GAS) infections during last decade. Pathogen genetic factors linked to this increase need assessment.METHODS: We investigated epidemiological characteristics of emm89 GAS bacteremic infections, including 7-day and 30-day case-fatality rates, in Finland during 2004-2014 and linked them to whole-genome sequencing data obtained from corresponding strains. The Fisher exact test and exact logistic regression were used to compare differences between bacteremic infections due to emm89 GAS belonging to different genetic clades and subclades.RESULTS: Out of 1928 cases of GAS bacteremic infection, 278 were caused by emm89 GAS. We identified 2 genetically distinct clades, arbitrarily designated clade 2 and clade 3. Both clades were present during 2004-2008, but clade 3 increased rapidly from 2009 onward. Six subclades (designated subclades A-F) were identified within clade 3, based on phylogenetic core genome analysis. The case-fatality rate differed significantly between subclades (P < .05), with subclade D having the highest 30-day estimated case-fatality rate (19% vs 3%-14%).CONCLUSIONS: A new emm89 clone, clade 3, emerged in 2009 and spread rapidly in Finland. Patients infected with certain subclades of clade 3 were significantly more likely to die. A specific polymerase chain reaction assay was developed to follow the spread of subclade D in 2015.
AB - BACKGROUND: Many countries worldwide have reported increasing numbers of emm89 group A Streptococcus (GAS) infections during last decade. Pathogen genetic factors linked to this increase need assessment.METHODS: We investigated epidemiological characteristics of emm89 GAS bacteremic infections, including 7-day and 30-day case-fatality rates, in Finland during 2004-2014 and linked them to whole-genome sequencing data obtained from corresponding strains. The Fisher exact test and exact logistic regression were used to compare differences between bacteremic infections due to emm89 GAS belonging to different genetic clades and subclades.RESULTS: Out of 1928 cases of GAS bacteremic infection, 278 were caused by emm89 GAS. We identified 2 genetically distinct clades, arbitrarily designated clade 2 and clade 3. Both clades were present during 2004-2008, but clade 3 increased rapidly from 2009 onward. Six subclades (designated subclades A-F) were identified within clade 3, based on phylogenetic core genome analysis. The case-fatality rate differed significantly between subclades (P < .05), with subclade D having the highest 30-day estimated case-fatality rate (19% vs 3%-14%).CONCLUSIONS: A new emm89 clone, clade 3, emerged in 2009 and spread rapidly in Finland. Patients infected with certain subclades of clade 3 were significantly more likely to die. A specific polymerase chain reaction assay was developed to follow the spread of subclade D in 2015.
KW - Streptococcus pyogenes
KW - Bacteremia
KW - Whole genome sequencing
U2 - 10.1093/infdis/jiw468
DO - 10.1093/infdis/jiw468
M3 - Article
C2 - 27707808
SN - 0022-1899
VL - 214
SP - 1987
EP - 1995
JO - Journal of Infectious Diseases
JF - Journal of Infectious Diseases
IS - 12
ER -