{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,6]],"date-time":"2026-10-06T13:54:06Z","timestamp":1791294846406,"version":"4.1.0"},"reference-count":58,"publisher":"American Society for Microbiology","issue":"3","license":[{"start":{"date-parts":[[2018,5,15]],"date-time":"2018-05-15T00:00:00Z","timestamp":1526342400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2018,7,5]],"date-time":"2018-07-05T00:00:00Z","timestamp":1530748800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"funder":[{"name":"Integrated Cellular Imaging Pediatric Core"},{"name":"Emory+Children's Pediatric Research Center"},{"DOI":"10.13039\/100000002","name":"HHS | National Institutes of Health","doi-asserted-by":"publisher","award":["R21AI112768-01A1"],"award-info":[{"award-number":["R21AI112768-01A1"]}],"id":[{"id":"10.13039\/100000002","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["mBio"],"published-print":{"date-parts":[[2018,7,5]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n                  <jats:p>\n                    <jats:named-content content-type=\"genus-species\">Streptococcus pneumoniae<\/jats:named-content>\n                    acquires genes for resistance to antibiotics such as streptomycin (Str) or trimethoprim (Tmp) by recombination via transformation of DNA released by other pneumococci and closely related species. Using naturally transformable pneumococci, including strain D39 serotype 2 (S2) and TIGR4 (S4), we studied whether pneumococcal nasopharyngeal transformation was symmetrical, asymmetrical, or unidirectional. Incubation of S2\n                    <jats:sup>Tet<\/jats:sup>\n                    and S4\n                    <jats:sup>Str<\/jats:sup>\n                    in a bioreactor simulating the human nasopharynx led to the generation of Spn\n                    <jats:sup>Tet\/Str<\/jats:sup>\n                    recombinants. Double-resistant pneumococci emerged soon after 4\u00a0h postinoculation at a recombination frequency (rF) of 2.5 \u00d7 10\n                    <jats:sup>\u22124<\/jats:sup>\n                    while peaking after 8\u00a0h at a rF of 1.1 \u00d7 10\n                    <jats:sup>\u22123<\/jats:sup>\n                    . Acquisition of antibiotic resistance genes by transformation was confirmed by treatment with DNase I. A high-throughput serotyping method demonstrated that all double-resistant pneumococci belonged to one serotype lineage (S2\n                    <jats:sup>Tet\/Str<\/jats:sup>\n                    ) and therefore that unidirectional transformation had occurred. Neither heterolysis nor availability of DNA for transformation was a factor for unidirectional transformation given that the density of each strain and extracellular DNA (eDNA) released from both strains were similar. Unidirectional transformation occurred regardless of the antibiotic-resistant gene carried by donors or acquired by recipients and regardless of whether competence-stimulating peptide-receptor cross talk was allowed. Moreover, unidirectional transformation occurred when two donor strains (e.g., S4\n                    <jats:sup>Str<\/jats:sup>\n                    and S19F\n                    <jats:sup>Tmp<\/jats:sup>\n                    ) were incubated together, leading to S19F\n                    <jats:sup>Str\/Tmp<\/jats:sup>\n                    but at a rF 3 orders of magnitude lower (4.9 \u00d7 10\n                    <jats:sup>\u22126<\/jats:sup>\n                    ). We finally demonstrated that the mechanism leading to unidirectional transformation was due to inhibition of transformation of the donor by the recipient.\n                  <\/jats:p>\n                  <jats:p>\n                    <jats:bold>IMPORTANCE<\/jats:bold>\n                    Pneumococcal transformation in the human nasopharynx may lead to the acquisition of antibiotic resistance genes or genes encoding new capsular variants. Antibiotics and vaccines are currently putting pressure on a number of strains, leading to an increase in antibiotic resistance and serotype replacement. These pneumococcal strains are also acquiring virulence traits from vaccine types via transformation. In this study, we recapitulated multiple-strain colonization with strains carrying a resistance marker and selected for those acquiring resistance to two or three antibiotics, such as would occur in the human nasopharynx. Strains acquiring dual and triple resistance originated from one progenitor, demonstrating that transformation was unidirectional. Unidirectional transformation was the result of inhibition of transformation of donor strains. Unidirectional transformation has implications for the understanding of acquisition patterns of resistance determinants or capsule-switching events.\n                  <\/jats:p>","DOI":"10.1128\/mbio.00561-18","type":"journal-article","created":{"date-parts":[[2018,5,14]],"date-time":"2018-05-14T05:33:51Z","timestamp":1526276031000},"update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":33,"title":["A Mechanism of Unidirectional Transformation, Leading to Antibiotic Resistance, Occurs within Nasopharyngeal Pneumococcal Biofilm Consortia"],"prefix":"10.1128","volume":"9","author":[{"given":"Santiago M.","family":"Lattar","sequence":"first","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xueqing","family":"Wu","sequence":"additional","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jennifer","family":"Brophy","sequence":"additional","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fuminori","family":"Sakai","sequence":"additional","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keith P.","family":"Klugman","sequence":"additional","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jorge E.","family":"Vidal","sequence":"additional","affiliation":[{"name":"Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia, USA"},{"name":"Antibiotic Resistance Center, School of Medicine, Emory University, Atlanta, Georgia, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/S0140-6736(09)61204-6"},{"key":"e_1_3_2_3_2","doi-asserted-by":"publisher","DOI":"10.1093\/aje\/kwp316"},{"key":"e_1_3_2_4_2","volume-title":"Streptococcus pneumoniae: molecular biology and mechanisms of disease","author":"Tomasz A","year":"2000","unstructured":"Tomasz A. 2000. 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