{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T02:46:53Z","timestamp":1773283613021,"version":"3.50.1"},"reference-count":26,"publisher":"American Society for Microbiology","issue":"2","license":[{"start":{"date-parts":[[2012,2,1]],"date-time":"2012-02-01T00:00:00Z","timestamp":1328054400000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.asm.org\/non-commercial-tdm-license"}],"content-domain":{"domain":["journals.asm.org"],"crossmark-restriction":true},"short-container-title":["Antimicrob Agents Chemother"],"published-print":{"date-parts":[[2012,2]]},"abstract":"<jats:title>ABSTRACT<\/jats:title>\n          <jats:p>\n            We conducted population-based surveillance for pneumococcal bacteremia within a 5-county region surrounding Philadelphia from October 2001 through September 2008, the period following introduction of the seven-valent pneumococcal conjugate vaccine. Erythromycin resistance increased from 14.7% in 2001-2002 to 20.3% in 2007-2008, while the resistance rate to penicillin (MIC, \u22652 \u03bcg\/ml) decreased from 7.2% to 4.2% during the same period. The most predominant serotypes associated with erythromycin resistance in 2007-2008 included 19A (29.7%), 15A (29.2%), 6C (10.1%), 3 (5.6%), and 6A (4.5%). The molecular mechanisms for the increasing erythromycin resistance were mainly due to the growing presence of\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">mef(A)<\/jats:named-content>\n            negative\n            <jats:italic>erm<\/jats:italic>\n            (B)\n            <jats:sup>\n              <jats:italic>+<\/jats:italic>\n            <\/jats:sup>\n            and\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">mef(A)<\/jats:named-content>\n            <jats:sup>\n              <jats:italic>+<\/jats:italic>\n            <\/jats:sup>\n            <jats:italic>erm<\/jats:italic>\n            (B)\n            <jats:sup>\n              <jats:italic>+<\/jats:italic>\n            <\/jats:sup>\n            genotypes, which increased from 20.0% to 46.1% and from 1.8% to 19.1%, respectively, from 2001-2002 to 2007-2008. However,\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">mef(A)<\/jats:named-content>\n            -mediated erythromycin resistance decreased from 72.7% in 2001-2002 to 34.8% in 2007-2008. Serotypes related to the\n            <jats:italic>erm<\/jats:italic>\n            (B) gene were 15A (45.6%), 19A (20.9%), 3 (10.1%), and 6B (6.3%); serotypes related to the\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">mef(A)<\/jats:named-content>\n            gene were 6A (18.6%), 19A (15.0%), 6C (9.3%), and 14(8.4%); serotypes associated with the presence of both\n            <jats:italic>erm<\/jats:italic>\n            (B) and\n            <jats:named-content xmlns:xlink=\"http:\/\/www.w3.org\/1999\/xlink\" content-type=\"genus-species\" xlink:type=\"simple\">mef(A)<\/jats:named-content>\n            were 19A (81.5%), 15A (7.7%), and 19F (6.2%). Pulsed-field gel electrophoresis analysis demonstrated that erythromycin-resistant isolates within the 19A serotype were genetically diverse and related to several circulating international clones. In contrast, erythromycin-resistant isolates within the 15A serotype consisted of clonally identical or closely related isolates.\n          <\/jats:p>","DOI":"10.1128\/aac.05122-11","type":"journal-article","created":{"date-parts":[[2011,11,30]],"date-time":"2011-11-30T02:31:59Z","timestamp":1322620319000},"page":"743-750","update-policy":"https:\/\/doi.org\/10.1128\/asmj-crossmark-policy-page","source":"Crossref","is-referenced-by-count":13,"title":["Serotype Emergence and Genotype Distribution among Macrolide-Resistant Invasive Streptococcus Pneumoniae Isolates in the Postconjugate Vaccine (PCV-7) Era"],"prefix":"10.1128","volume":"56","author":[{"given":"Zhenying","family":"Liu","sequence":"first","affiliation":[{"name":"Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Irving","family":"Nachamkin","sequence":"additional","affiliation":[{"name":"Departments of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Paul H.","family":"Edelstein","sequence":"additional","affiliation":[{"name":"Departments of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ebbing","family":"Lautenbach","sequence":"additional","affiliation":[{"name":"Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania, USA"},{"name":"Departments of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Joshua P.","family":"Metlay","sequence":"additional","affiliation":[{"name":"Center for Clinical Epidemiology and Biostatistics, University of Pennsylvania, Philadelphia, Pennsylvania, USA"},{"name":"Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"235","reference":[{"key":"e_1_3_2_2_2","unstructured":"ABIBiodisk. 2004. 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