{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,27]],"date-time":"2026-04-27T19:16:27Z","timestamp":1777317387661,"version":"3.51.4"},"reference-count":27,"publisher":"Proceedings of the National Academy of Sciences","issue":"11","content-domain":{"domain":["www.pnas.org"],"crossmark-restriction":true},"short-container-title":["Proc. Natl. Acad. Sci. U.S.A."],"published-print":{"date-parts":[[2002,5,28]]},"abstract":"<jats:p>\n            Methicillin-resistant\n            <jats:italic>Staphylococcus aureus<\/jats:italic>\n            (MRSA) is a major cause of hospital-acquired infections that are becoming increasingly difficult to combat because of emerging resistance to all current antibiotic classes. The evolutionary origins of MRSA are poorly understood, no rational nomenclature exists, and there is no consensus on the number of major MRSA clones or the relatedness of clones described from different countries. We resolve all of these issues and provide a more thorough and precise analysis of the evolution of MRSA clones than has previously been possible. Using multilocus sequence typing and an algorithm,\n            <jats:sc>burst<\/jats:sc>\n            , we analyzed an international collection of 912 MRSA and methicillin-susceptible\n            <jats:italic>S. aureus<\/jats:italic>\n            (MSSA) isolates. We identified 11 major MRSA clones within five groups of related genotypes. The putative ancestral genotype of each group and the most parsimonious patterns of descent of isolates from each ancestor were inferred by using\n            <jats:sc>burst<\/jats:sc>\n            , which, together with analysis of the methicillin resistance genes, established the likely evolutionary origins of each major MRSA clone, the genotype of the original MRSA clone and its MSSA progenitor, and the extent of acquisition and horizontal movement of the methicillin resistance genes. Major MRSA clones have arisen repeatedly from successful epidemic MSSA strains, and isolates with decreased susceptibility to vancomycin, the antibiotic of last resort, are arising from some of these major MRSA clones, highlighting a depressing progression of increasing drug resistance within a small number of ecologically successful\n            <jats:italic>S. aureus<\/jats:italic>\n            genotypes.\n          <\/jats:p>","DOI":"10.1073\/pnas.122108599","type":"journal-article","created":{"date-parts":[[2002,7,26]],"date-time":"2002-07-26T14:46:49Z","timestamp":1027694809000},"page":"7687-7692","update-policy":"https:\/\/doi.org\/10.1073\/pnas.cm10313","source":"Crossref","is-referenced-by-count":1243,"title":["The evolutionary history of methicillin-resistant\n            <i>Staphylococcus aureus<\/i>\n            (MRSA)"],"prefix":"10.1073","volume":"99","author":[{"given":"Mark C.","family":"Enright","sequence":"first","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]},{"given":"D. Ashley","family":"Robinson","sequence":"additional","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]},{"given":"Gaynor","family":"Randle","sequence":"additional","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]},{"given":"Edward J.","family":"Feil","sequence":"additional","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]},{"given":"Hajo","family":"Grundmann","sequence":"additional","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]},{"given":"Brian G.","family":"Spratt","sequence":"additional","affiliation":[{"name":"Department of Biology and Biochemistry, University of Bath, Bath BA2 7AY, United Kingdom; Institute of Molecular Medicine, John Radcliffe Hospital, Oxford, OX3 9DU, United Kingdom; Division of Microbiology and Infectious Diseases, University Hospital Nottingham, Nottingham, NG7 2UH, United Kingdom; and Department of Infectious Disease Epidemiology, Faculty of Medicine, Imperial College, St. Mary's Hospital, London W2 1PG, United Kingdom"}]}],"member":"341","published-online":{"date-parts":[[2002,5,21]]},"reference":[{"key":"e_1_3_3_1_2","doi-asserted-by":"publisher","DOI":"10.1136\/bmj.1.5219.124-a"},{"key":"e_1_3_3_2_2","doi-asserted-by":"publisher","DOI":"10.1097\/00006454-200012000-00009"},{"key":"e_1_3_3_3_2","first-page":"707","volume":"48","year":"1999","unstructured":"Morbid Mortal Wkly Rep 48, 707\u2013710 (1999).","journal-title":"Morbid Mortal Wkly Rep"},{"key":"e_1_3_3_4_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0966-842X(01)02175-8"},{"key":"e_1_3_3_5_2","volume-title":"Diagnostic Molecular Microbiology","author":"Hiramatsu K","year":"2002","unstructured":"K Hiramatsu, M Kuroda, T Baba, K Okuma Diagnostic Molecular Microbiology, ed D Persing (Am. 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