{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,30]],"date-time":"2026-01-30T05:19:43Z","timestamp":1769750383169,"version":"3.49.0"},"reference-count":26,"publisher":"Microbiology Society","issue":"1","license":[{"start":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T00:00:00Z","timestamp":1769644800000},"content-version":"unspecified","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100005224","name":"National Center for Immunization and Respiratory Diseases","doi-asserted-by":"crossref","id":[{"id":"10.13039\/100005224","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,1,29]]},"abstract":"<jats:p>\n                    <jats:bold>Background.<\/jats:bold>\n                    The propensity of\n                    <jats:italic>Streptococcus pyogenes<\/jats:italic>\n                    (group A\n                    <jats:italic>Streptococcus<\/jats:italic>\n                    ) to invade normally sterile sites and cause invasive group A\n                    <jats:italic>Streptococcus<\/jats:italic>\n                    (iGAS) disease varies across strains, which are classified using the\n                    <jats:italic>emm<\/jats:italic>\n                    gene. Between 2015 and 2017, multistate iGAS surveillance identified an ~150-fold increase of one particular\n                    <jats:italic>emm<\/jats:italic>\n                    type,\n                    <jats:italic>emm<\/jats:italic>\n                    49. This genomic epidemiological analysis aimed to identify bacterial, patient and societal factors associated with this expansion.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Methods.<\/jats:bold>\n                    We analysed 1322\n                    <jats:italic>emm<\/jats:italic>\n                    49 iGAS cases and the genome sequences of the clinical isolates acquired through the population-based Active Bacterial Core surveillance during 2015\u20132022. For each invasive case, we received both a cultured isolate and a standardized case report form that included basic demographic attributes and risk factors of infection. A phylogeographic analysis was performed to reconstruct the divergence times and spatial dispersal history within our\n                    <jats:italic>emm<\/jats:italic>\n                    49 collection.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Results.<\/jats:bold>\n                    Compared to other\n                    <jats:italic>emm<\/jats:italic>\n                    types,\n                    <jats:italic>emm<\/jats:italic>\n                    49 cases were more common in males (63.5% vs. 58.3%,\n                    <jats:italic>P<\/jats:italic>\n                    =0.0143), in people experiencing homelessness (34.0% vs. 17.5%,\n                    <jats:italic>P<\/jats:italic>\n                    &lt;0.0001) and in people who inject drugs (23.7% vs. 13.1%,\n                    <jats:italic>P<\/jats:italic>\n                    &lt;0.0001). Time-scaled phylogeographic analysis estimated that the most recent common ancestor of the post-2015 expansion isolates occurred around 2004 and that\n                    <jats:italic>emm<\/jats:italic>\n                    49 emerged in the western USA.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>Conclusion.<\/jats:bold>\n                    Our findings suggest that the current nationwide outbreak may have originated from the introduction of\n                    <jats:italic>emm<\/jats:italic>\n                    49 into disadvantaged (homeless and\/or injecting drug users) adult subpopulations. This study underscores how social marginalization and broader social determinants of health can shape iGAS strain epidemiology in the USA.\n                  <\/jats:p>","DOI":"10.1099\/mgen.0.001615","type":"journal-article","created":{"date-parts":[[2026,1,29]],"date-time":"2026-01-29T15:17:19Z","timestamp":1769699839000},"source":"Crossref","is-referenced-by-count":0,"title":["The rise and spread of invasive emm49 Streptococcus pyogenes in the USA"],"prefix":"10.1099","volume":"12","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9628-2051","authenticated-orcid":false,"given":"Benjamin","family":"Metcalf","sequence":"first","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Srinivas","family":"Nanduri","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuan","family":"Li","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhongya","family":"Li","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Saundra","family":"Mathis","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joy","family":"Rivers","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sopio","family":"Chochua","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bernard","family":"Beall","sequence":"additional","affiliation":[{"name":"Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, 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