{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,23]],"date-time":"2026-06-23T17:11:17Z","timestamp":1782234677649,"version":"3.54.5"},"reference-count":24,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2019,7,31]],"date-time":"2019-07-31T00:00:00Z","timestamp":1564531200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002341","name":"Academy of Finland","doi-asserted-by":"publisher","award":["12859785"],"award-info":[{"award-number":["12859785"]}],"id":[{"id":"10.13039\/501100002341","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100008376","name":"Helsingin ja Uudenmaan Sairaanhoitopiiri","doi-asserted-by":"publisher","award":["30101"],"award-info":[{"award-number":["30101"]}],"id":[{"id":"10.13039\/100008376","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Microorganisms"],"abstract":"<jats:p>In 2019, more than 200 cases of Chlamydia trachomatis negative\/equivocal by the Aptima Combo 2 assay (AC2, target: 23S rRNA) with slightly elevated relative light units (RLUs), but positive by the Aptima Chlamydia trachomatis assay (ACT, target: 16S rRNA) have been detected in Finland To identify the cause of the AC2 CT false-negative specimens, we sequenced parts of the CT 23S rRNA gene in 40 specimens that were AC2 negative\/equivocal but ACT positive. A single nucleotide polymorphism (SNP; C1515T in the C. trachomatis 23S rRNA gene) was revealed in 39 AC2\/ACT discordant specimens. No decrease in the number of mandatorily notified C. trachomatis cases was observed nationally in Finland in 2010\u20132019. When RLUs obtained for AC2 negative specimens were retrospectively evaluated in 2011\u20132019, a continuous increase in the proportion of samples with RLUs 10\u201319 was observed since 2014, and a slight increase in the proportion of samples with RLUs 20\u201384 in 2017\u20132019, indicating that the Finnish new variant of C. trachomatis might have been spreading nationally for several years. This emphasizes that careful surveillance of epidemiology, positivity rate and test performance are mandatory to detect any changes affecting detection of infections.<\/jats:p>","DOI":"10.3390\/microorganisms7080227","type":"journal-article","created":{"date-parts":[[2019,7,31]],"date-time":"2019-07-31T11:37:07Z","timestamp":1564573027000},"page":"227","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":26,"title":["The Finnish New Variant of Chlamydia trachomatis with a Single Nucleotide Polymorphism in the 23S rRNA Target Escapes Detection by the Aptima Combo 2 Test"],"prefix":"10.3390","volume":"7","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4428-7536","authenticated-orcid":false,"given":"Kati","family":"Hokynar","sequence":"first","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Kaisu","family":"Rantakokko-Jalava","sequence":"additional","affiliation":[{"name":"Department of Clinical Microbiology, Turku University Hospital, 20500 Turku, Finland"},{"name":"Department of Virology, University of Turku, 20500 Turku, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Antti","family":"Hakanen","sequence":"additional","affiliation":[{"name":"Department of Clinical Microbiology, Turku University Hospital, 20500 Turku, Finland"},{"name":"Department of Virology, University of Turku, 20500 Turku, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Marika","family":"Havana","sequence":"additional","affiliation":[{"name":"SYNLAB Finland, 00310 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Laura","family":"Mannonen","sequence":"additional","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Pia","family":"Jokela","sequence":"additional","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2911-3212","authenticated-orcid":false,"given":"Satu","family":"Kurkela","sequence":"additional","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Maija","family":"Lappalainen","sequence":"additional","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Magnus","family":"Unemo","sequence":"additional","affiliation":[{"name":"World Health Organization (WHO) Collaborating Centre for Gonorrhoea and other Sexually Transmitted Infections (STIs), National Reference Laboratory for STIs, Department of Laboratory Medicine, Faculty of Medicine and Health, \u00d6rebro University, SE-701 85 \u00d6rebro, Sweden"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7413-6793","authenticated-orcid":false,"given":"Mirja","family":"Puolakkainen","sequence":"additional","affiliation":[{"name":"Virology, University of Helsinki and Helsinki University Hospital, 00014 Helsinki, Finland"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2019,7,31]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Rowley, J., Van der Hoorn, S., Korenromp, E., Low, N., Unemo, M., Abu-Raddad, L.J., Chico, R.M., Smolak, A., Newman, L., and Gottlieb, S. 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