{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T18:05:07Z","timestamp":1785434707192,"version":"3.56.0"},"reference-count":39,"publisher":"Public Library of Science (PLoS)","issue":"7","license":[{"start":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T00:00:00Z","timestamp":1785369600000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100009619","name":"Japan Agency for Medical Research and Development","doi-asserted-by":"publisher","award":["JP22fk0108612 and JP22fk0108540"],"award-info":[{"award-number":["JP22fk0108612 and JP22fk0108540"]}],"id":[{"id":"10.13039\/100009619","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["www.plosone.org"],"crossmark-restriction":false},"short-container-title":["PLoS One"],"abstract":"<jats:p>\n                    Group B\n                    <jats:italic>Streptococcus<\/jats:italic>\n                    (GBS) colonization in pregnant women is a major risk factor for neonatal diseases; however, molecular epidemiological studies on GBS in Japan remain limited. We characterized 219 GBS isolates recovered from vaginal screening cultures at a general hospital in Osaka Prefecture, Japan between 2021 and 2023. Capsular type, clonal complex\/sequence type (CC\/ST), virulence factors (pilus islands, Alp family, Srr1\/Srr2, and HvgA), and antimicrobial resistance determinants were analyzed using whole-genome sequencing. The predominant lineages were CC19 (27.9%), CC23 (21.9%), and CC1 (21.0%), whereas the hypervirulent CC17 lineage accounted for only 5.5% of isolates. Capsular type Ia, III, and V comprised &gt;60% of the isolates. PI-1\/PI-2a (58.0%) was the predominant pilus profile, and\n                    <jats:italic>rib<\/jats:italic>\n                    (35.2%) was the most frequent Alp family gene. The hypervirulence-associated markers\n                    <jats:italic>hvgA<\/jats:italic>\n                    and\n                    <jats:italic>srr2<\/jats:italic>\n                    were confined to capsular types III\/CC17 and IV\/CC452. All isolates were susceptible to \u03b2-lactams and vancomycin, whereas resistance to macrolides, clindamycin, and levofloxacin was observed at varying frequencies. These findings provide a pre-vaccine molecular baseline for maternal GBS carriage in Japan and highlight\n                    <jats:italic>srr2<\/jats:italic>\n                    -positive CC452 as a potential emerging lineage of concern.\n                  <\/jats:p>","DOI":"10.1371\/journal.pone.0354799","type":"journal-article","created":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:56:07Z","timestamp":1785434167000},"page":"e0354799","update-policy":"https:\/\/doi.org\/10.1371\/journal.pone.corrections_policy","source":"Crossref","is-referenced-by-count":0,"title":["Genomic epidemiology of Group B Streptococcus colonization among pregnant women in Japan, 2021\u20132023"],"prefix":"10.1371","volume":"21","author":[{"given":"Chizu","family":"Nishi","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7072-5056","authenticated-orcid":true,"given":"Hirofumi","family":"Ohtaki","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8726-1913","authenticated-orcid":true,"given":"Masaki","family":"Karino","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiromi","family":"Uekita","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ayumi","family":"Sano","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tetsuya","family":"Kobayashi","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susumu","family":"Kaino","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yoshiki","family":"Sakamoto","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8987-0250","authenticated-orcid":true,"given":"Satoshi","family":"Nakano","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"340","published-online":{"date-parts":[[2026,7,30]]},"reference":[{"key":"pone.0354799.ref001","article-title":"Estimates of the Burden of Group B Streptococcal Disease Worldwide for Pregnant Women, Stillbirths, and Children","volume":"65","author":"AC Seale","year":"2017","journal-title":"Clin Infect Dis"},{"key":"pone.0354799.ref002","article-title":"Maternal Colonization With Group B Streptococcus and Serotype Distribution Worldwide: Systematic Review and Meta-analyses","volume":"65","author":"NJ Russell","year":"2017","journal-title":"Clin Infect Dis"},{"key":"pone.0354799.ref003","doi-asserted-by":"crossref","first-page":"437","DOI":"10.3389\/fmicb.2018.00437","article-title":"Group B streptococcal colonization, molecular characteristics, and epidemiology","volume":"9","author":"S Shabayek","year":"2018","journal-title":"Front Microbiol"},{"issue":"2","key":"pone.0354799.ref004","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1016\/S1473-3099(20)30478-3","article-title":"Safety and immunogenicity of a novel hexavalent group B streptococcus conjugate vaccine in healthy, non-pregnant adults: a phase 1\/2, randomised, placebo-controlled, observer-blinded, dose-escalation trial","volume":"21","author":"J Absalon","year":"2021","journal-title":"Lancet Infect Dis"},{"issue":"3","key":"pone.0354799.ref005","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1056\/NEJMoa2116045","article-title":"Potential for Maternally Administered Vaccine for Infant Group B Streptococcus","volume":"389","author":"SA Madhi","year":"2023","journal-title":"N Engl J Med"},{"issue":"3","key":"pone.0354799.ref006","doi-asserted-by":"crossref","first-page":"106261","DOI":"10.1016\/j.isci.2023.106261","article-title":"Safety and immunogenicity of the group B streptococcus vaccine AlpN in a placebo-controlled double-blind phase 1 trial","volume":"26","author":"M Gonzalez-Miro","year":"2023","journal-title":"iScience"},{"key":"pone.0354799.ref007","doi-asserted-by":"crossref","first-page":"1430901","DOI":"10.3389\/fimmu.2024.1430901","article-title":"Vaccines for Streptococcus agalactiae: current status and future perspectives","volume":"15","author":"JMS Pena","year":"2024","journal-title":"Front Immunol"},{"issue":"11","key":"pone.0354799.ref008","doi-asserted-by":"crossref","first-page":"2313","DOI":"10.1084\/jem.20092594","article-title":"The surface protein HvgA mediates group B streptococcus hypervirulence and meningeal tropism in neonates","volume":"207","author":"A Tazi","year":"2010","journal-title":"J Exp Med"},{"issue":"6","key":"pone.0354799.ref009","doi-asserted-by":"crossref","first-page":"1209","DOI":"10.1111\/mmi.13097","article-title":"Srr2, a multifaceted adhesin expressed by ST-17 hypervirulent Group B Streptococcus involved in binding to both fibrinogen and plasminogen","volume":"97","author":"A Six","year":"2015","journal-title":"Mol Microbiol"},{"key":"pone.0354799.ref010","doi-asserted-by":"crossref","first-page":"2483","DOI":"10.3390\/microorganisms10122483","article-title":"Group B Streptococcus: Virulence Factors and Pathogenic Mechanism","volume":"10","author":"Y Liu","year":"2022","journal-title":"Microorganisms"},{"key":"pone.0354799.ref011","doi-asserted-by":"crossref","first-page":"3100","DOI":"10.1128\/JCM.00277-10","article-title":"Clonal analysis of colonizing group B Streptococcus, serotype IV, an emerging pathogen in the United States","volume":"48","author":"MJ Diedrick","year":"2010","journal-title":"J Clin Microbiol"},{"issue":"6","key":"pone.0354799.ref012","doi-asserted-by":"crossref","first-page":"491","DOI":"10.3390\/antibiotics13060491","article-title":"Emergence of High-Level Gentamicin Resistance in Streptococcus agalactiae Hypervirulent Serotype IV ST1010 (CC452) Strains by Acquisition of a Novel Integrative and Conjugative Element","volume":"13","author":"R Creti","year":"2024","journal-title":"Antibiotics (Basel)"},{"issue":"1","key":"pone.0354799.ref013","doi-asserted-by":"crossref","DOI":"10.1093\/infdis\/jiaf491","article-title":"Prevalence of Candidate Vaccine Targets and Genomic Features of Pediatric Invasive Streptococcus Agalactiae in Japan","volume":"233","author":"M Kasai","year":"2026","journal-title":"J Infect Dis"},{"key":"pone.0354799.ref014","doi-asserted-by":"crossref","first-page":"559","DOI":"10.1007\/s10096-021-04396-y","article-title":"Epidemiology of group B streptococcal disease in infants younger than 1 year in Japan: a nationwide surveillance study 2016\u20132020","volume":"41","author":"M Shibata","year":"2022","journal-title":"Eur J Clin Microbiol Infect Dis"},{"key":"pone.0354799.ref015","doi-asserted-by":"crossref","DOI":"10.1017\/S0950268822001534","article-title":"Epidemiology and bacterial characteristics of invasive group B streptococcus disease: a population-based study in Japan in 2010-2020","volume":"150","author":"N Takeuchi","year":"2022","journal-title":"Epidemiol Infect"},{"key":"pone.0354799.ref016","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1016\/j.ijregi.2022.07.002","article-title":"Molecular characterization and antimicrobial resistance of Streptococcus agalactiae isolated from pregnant women in Japan, 2017\u20132021","volume":"4","author":"M Kawaguchiya","year":"2022","journal-title":"IJID Reg"},{"issue":"4","key":"pone.0354799.ref017","doi-asserted-by":"crossref","first-page":"812","DOI":"10.1017\/S0950268813001647","article-title":"Associations between capsular serotype, multilocus sequence type, and macrolide resistance in Streptococcus agalactiae isolates from Japanese infants with invasive infections","volume":"142","author":"M Morozumi","year":"2014","journal-title":"Epidemiol Infect"},{"issue":"5","key":"pone.0354799.ref018","doi-asserted-by":"crossref","first-page":"356","DOI":"10.7883\/yoken.67.356","article-title":"Characteristics of group B Streptococcus isolated from infants with invasive infections: a population-based study in Japan","volume":"67","author":"B Chang","year":"2014","journal-title":"Jpn J Infect Dis"},{"key":"pone.0354799.ref019","volume-title":"Guidelines for the Detection and Identification of Group B Streptococcus","author":"L Filkins","year":"2021"},{"key":"pone.0354799.ref020","volume-title":"Performance Standards for Antimicrobial Susceptibility Testing. 35th ed. CLSI supplement M100","author":"Clinical and Laboratory Standards Institute","year":"2025"},{"issue":"7","key":"pone.0354799.ref021","doi-asserted-by":"crossref","DOI":"10.1099\/jmm.0.001849","article-title":"Enrichment culture evaluation and characterization of Streptococcus agalactiae among pregnant women in Japan","volume":"73","author":"S Nakano","year":"2024","journal-title":"J Med Microbiol"},{"issue":"12","key":"pone.0354799.ref022","first-page":"000688","article-title":"GBS-SBG - GBS Serotyping by Genome Sequencing","volume":"7","author":"S Tiruvayipati","year":"2021","journal-title":"Microb Genom"},{"key":"pone.0354799.ref023","doi-asserted-by":"crossref","first-page":"124","DOI":"10.12688\/wellcomeopenres.14826.1","article-title":"Open-access bacterial population genomics: BIGSdb software, the PubMLST.org website and their applications","volume":"3","author":"KA Jolley","year":"2018","journal-title":"Wellcome Open Res"},{"issue":"1","key":"pone.0354799.ref024","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1093\/bioinformatics\/btw582","article-title":"PHYLOViZ 2.0: providing scalable data integration and visualization for multiple phylogenetic inference methods","volume":"33","author":"M Nascimento","year":"2017","journal-title":"Bioinformatics"},{"key":"pone.0354799.ref025","doi-asserted-by":"crossref","first-page":"1185753","DOI":"10.3389\/fmicb.2023.1185753","article-title":"Population genetics of group B Streptococcus from maternal carriage in an ethnically diverse community in London","volume":"14","author":"D Jamrozy","year":"2023","journal-title":"Front Microbiol"},{"issue":"4","key":"pone.0354799.ref026","first-page":"001399","article-title":"Genomic characterization of group B Streptococcus from Argentina: insights into prophage diversity, virulence factors and antibiotic resistance genes","volume":"11","author":"V Kovacec","year":"2025","journal-title":"Microb Genom"},{"key":"pone.0354799.ref027","doi-asserted-by":"crossref","first-page":"107608","DOI":"10.1016\/j.ijid.2024.107608","article-title":"Group B Streptococcus genomic epidemiology indicates that the neonatal disease-associated clonal complex 23 is the major lineage found colonizing pregnant women in Brazil","volume":"152","author":"L Oliveira","year":"2025","journal-title":"Int J Infect Dis"},{"issue":"7","key":"pone.0354799.ref028","doi-asserted-by":"crossref","first-page":"16067","DOI":"10.1038\/nmicrobiol.2016.67","article-title":"Maternal colonization with Streptococcus agalactiae and associated stillbirth and neonatal disease in coastal Kenya","volume":"1","author":"AC Seale","year":"2016","journal-title":"Nat Microbiol"},{"issue":"10","key":"pone.0354799.ref029","doi-asserted-by":"crossref","DOI":"10.1371\/journal.pone.0223256","article-title":"Genomic characterisation of perinatal Western Australian Streptococcus agalactiae isolates","volume":"14","author":"LL Furfaro","year":"2019","journal-title":"PLoS One"},{"key":"pone.0354799.ref030","doi-asserted-by":"crossref","first-page":"29799","DOI":"10.1038\/srep29799","article-title":"Serotype IV Streptococcus agalactiae ST-452 has arisen from large genomic recombination events between CC23 and the hypervirulent CC17 lineages","volume":"6","author":"E Campisi","year":"2016","journal-title":"Sci Rep"},{"key":"pone.0354799.ref031","doi-asserted-by":"crossref","first-page":"585","DOI":"10.3201\/eid2014.140759","article-title":"Population structure and antimicrobial resistance of invasive serotype IV group B Streptococcus, Toronto, Ontario, Canada","volume":"21","author":"S Teatero","year":"2015","journal-title":"Emerg Infect Dis"},{"key":"pone.0354799.ref032","doi-asserted-by":"crossref","first-page":"249","DOI":"10.1099\/jmm.0.052951-0","article-title":"Distribution of pilus islands of group B streptococcus associated with maternal colonization and invasive disease in South Africa","volume":"62","author":"The PoPS Trial Team","year":"2013","journal-title":"J Med Microbiol"},{"issue":"1","key":"pone.0354799.ref033","doi-asserted-by":"crossref","first-page":"740","DOI":"10.1186\/s12879-024-09625-1","article-title":"Molecular epidemiology and virulence factors of group B Streptococcus in South Korea according to the invasiveness","volume":"24","author":"JH Choi","year":"2024","journal-title":"BMC Infect Dis"},{"key":"pone.0354799.ref034","doi-asserted-by":"crossref","first-page":"20047","DOI":"10.1038\/srep20047","article-title":"Clonal Complex 17 Group B Streptococcus strains causing invasive disease in neonates and adults originate from the same genetic pool","volume":"6","author":"S Teatero","year":"2016","journal-title":"Sci Rep"},{"key":"pone.0354799.ref035","doi-asserted-by":"crossref","first-page":"1265","DOI":"10.3389\/fmicb.2016.01265","article-title":"Genomic Analysis Reveals Multi-Drug Resistance Clusters in Group B Streptococcus CC17 Hypervirulent Isolates Causing Neonatal Invasive Disease in Southern Mainland China","volume":"7","author":"E Campisi","year":"2016","journal-title":"Front Microbiol"},{"key":"pone.0354799.ref036","doi-asserted-by":"crossref","first-page":"2721","DOI":"10.3201\/eid2611.201669","article-title":"Multidrug-Resistant Hypervirulent Group B Streptococcus in Neonatal Invasive Infections, France, 2007\u20132019","volume":"26","author":"C Plainvert","year":"2020","journal-title":"Emerg Infect Dis"},{"issue":"1","key":"pone.0354799.ref037","doi-asserted-by":"crossref","first-page":"365","DOI":"10.1186\/s12866-024-03521-z","article-title":"Unveiling the genetic landscape of Streptococcus agalactiae bacteremia: emergence of hypervirulent CC1 strains and new CC283 strains in Tehran, Iran","volume":"24","author":"A Mohammadi","year":"2024","journal-title":"BMC Microbiol"},{"issue":"50","key":"pone.0354799.ref038","doi-asserted-by":"crossref","first-page":"35982","DOI":"10.1074\/jbc.M113.513358","article-title":"Characterization of fibrinogen binding by glycoproteins Srr1 and Srr2 of Streptococcus agalactiae","volume":"288","author":"HS Seo","year":"2013","journal-title":"J Biol Chem"},{"issue":"1","key":"pone.0354799.ref039","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1186\/s12866-024-03374-6","article-title":"The serine-rich repeat glycoprotein Srr2 mediates Streptococcus agalactiae interaction with host fibronectin","volume":"24","author":"A Pellegrini","year":"2024","journal-title":"BMC Microbiol"}],"container-title":["PLOS One"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0354799","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:56:13Z","timestamp":1785434173000},"score":1,"resource":{"primary":{"URL":"https:\/\/dx.plos.org\/10.1371\/journal.pone.0354799"}},"subtitle":[],"editor":[{"given":"Baochuan","family":"Lin","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"editor"}]}],"short-title":[],"issued":{"date-parts":[[2026,7,30]]},"references-count":39,"journal-issue":{"issue":"7","published-online":{"date-parts":[[2026,7,30]]}},"URL":"https:\/\/doi.org\/10.1371\/journal.pone.0354799","relation":{},"ISSN":["1932-6203"],"issn-type":[{"value":"1932-6203","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,7,30]]}}}