{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,2]],"date-time":"2025-12-02T18:47:21Z","timestamp":1764701241223,"version":"build-2065373602"},"reference-count":37,"publisher":"MDPI AG","issue":"11","license":[{"start":{"date-parts":[[2025,10,29]],"date-time":"2025-10-29T00:00:00Z","timestamp":1761696000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>Invasive group A streptococcal (iGAS) infections are increasingly recognized as a global public health concern, with a notable resurgence observed among pediatric populations in high-income countries following the relaxation of COVID-19-related restrictions. While the most commonly implicated emm types in invasive disease are emm1 and emm3, the global distribution of Streptococcus pyogenes strains is highly diverse, posing challenges for surveillance and vaccine development. We describe a 3-year-old boy with a femoral subperiosteal abscess, a rare clinical manifestation of iGAS, caused by an emm6.10 S. pyogenes strain. The diagnosis was confirmed by positive blood cultures and magnetic resonance imaging. Antibiotic therapy included intravenous ceftriaxone followed by oral amoxicillin, and then prolonged oral clindamycin was introduced due to the deep-seated nature of the infection. Molecular typing was performed by the national reference center as part of routine surveillance of invasive strains. This case emphasizes the importance of recognizing atypical clinical presentations of iGAS in children and the crucial role of strain typing in epidemiological monitoring. It also illustrates how the remarkable emm-type diversity of S. pyogenes remains a major obstacle to effective vaccine design, despite ongoing efforts with multivalent M-protein-based candidates and alternative strategies targeting conserved antigens. Enhanced global surveillance and inclusive vaccine design are urgently needed to address the full spectrum of circulating GAS strains.<\/jats:p>","DOI":"10.3390\/microorganisms13112475","type":"journal-article","created":{"date-parts":[[2025,10,29]],"date-time":"2025-10-29T17:38:22Z","timestamp":1761759502000},"page":"2475","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Rare emm6.10 Streptococcus pyogenes Causing an Unusual Invasive Infection in a Child: Clinical and Genomic Insights"],"prefix":"10.3390","volume":"13","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0304-7624","authenticated-orcid":false,"given":"Laurent","family":"Blairon","sequence":"first","affiliation":[{"name":"Department of Laboratory Medicine, Iris Hospitals South, 1050 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4915-1339","authenticated-orcid":false,"given":"Marie","family":"Tr\u00e9-Hardy","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, Namur Research Institute for Life Sciences, University of Namur, 5000 Namur, Belgium"},{"name":"Faculty of Medicine, Universit\u00e9 libre de Bruxelles, 1070 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2137-2068","authenticated-orcid":false,"given":"Veerle","family":"Matheeussen","sequence":"additional","affiliation":[{"name":"National Reference Centre for Invasive \u03b2-Hemolytic Streptococci Non-Group B, Antwerp University Hospital, 2650 Edegem, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5267-5080","authenticated-orcid":false,"given":"Sien De","family":"Koster","sequence":"additional","affiliation":[{"name":"National Reference Centre for Invasive \u03b2-Hemolytic Streptococci Non-Group B, Antwerp University Hospital, 2650 Edegem, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2766-1805","authenticated-orcid":false,"given":"Marie","family":"Cassart","sequence":"additional","affiliation":[{"name":"Department of Medical Imaging, Iris Hospitals South, 1050 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sarah","family":"Heenen","sequence":"additional","affiliation":[{"name":"Department of Intensive Care Medicine, Iris Hospitals South, 1050 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0330-7086","authenticated-orcid":false,"given":"Andrea","family":"Nebbioso","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Iris Hospitals South, 1050 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nancy","family":"Vitali","sequence":"additional","affiliation":[{"name":"Department of Pediatrics, Iris Hospitals South, 1050 Brussels, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Flamant, A., Demirjian, A., Lamagni, T., Toubiana, J., Smeesters, P.R., and Cohen, J.F. 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