Ana Friães, Rafael Mamede, Beatriz Santos, Gina Marrão, José Melo-Cristino, Mario Ramirez
{"title":"Increase of macrolide resistance among <i>Streptococcus pyogenes</i> pharyngitis driven by a <i>mef</i>(A)-<i>msr</i>(D)/<i>emm</i>2-ST55 lineage in Portugal (2014-2019).","authors":"Ana Friães, Rafael Mamede, Beatriz Santos, Gina Marrão, José Melo-Cristino, Mario Ramirez","doi":"10.1128/aac.00968-25","DOIUrl":null,"url":null,"abstract":"<p><p>Increases in macrolide resistance occurred recently among <i>Streptococcus pyogenes</i> (Group A <i>Streptococcus</i>, GAS) in some countries. While the importance of monitoring the clinical and molecular epidemiology of non-invasive GAS is increasingly recognized, most surveillance focuses on invasive infections, since culture is rarely performed in tonsillo-pharyngitis. We determined the antimicrobial susceptibility and characterized the macrolide-resistant lineages of 2,002 pharyngeal isolates recovered in a Portuguese hospital in 2014-2019. There were seasonal variations in the numbers of recovered isolates, with peaks shifting between March-July and October-December, but consistently low numbers in August and September. Macrolide-resistant and macrolide-susceptible GAS presented independent seasonal and clonal dynamics, with resistant isolates showing lower genetic diversity and minimal overlap with susceptible lineages. Overall, 84 (4%), 77 (4%), and 52 (3%) isolates were resistant to erythromycin, clindamycin, and tetracycline, respectively. Until 2018, macrolide resistance was mainly due to an internationally disseminated <i>emm</i>77-ST63 lineage carrying <i>erm</i>(A) and <i>tet</i>(O) in ICE<i>Sp2905</i> and an <i>emm</i>75-ST49 lineage carrying <i>mef</i>(A)-<i>msr</i>(D) in a novel ɸ1207.3 variant. In 2019, resistance peaked at 9% due to the rapid expansion of <i>mef</i>(A)-<i>msr</i>(D)-positive <i>emm</i>2-ST55 isolates, replacing previous lineages. Other minor resistant lineages carried mostly <i>erm</i>(B) in a diversity of mobile genetic elements, including <i>emm</i>75-ST150, <i>emm</i>9-ST75, <i>emm</i>11-ST403, <i>emm</i>12-ST36, <i>emm</i>76-ST50, and <i>emm</i>77-ST399 [<i>erm</i>(T)]. Tetracycline resistance was associated with the genes <i>tet</i>(M) and <i>tet</i>(O), in most cases co-located in the same genetic elements as the <i>erm</i> genes. This study reveals clonal changes among macrolide-resistant GAS driving fluctuations in macrolide resistance and associated phenotypes.</p>","PeriodicalId":8152,"journal":{"name":"Antimicrobial Agents and Chemotherapy","volume":" ","pages":"e0096825"},"PeriodicalIF":4.5000,"publicationDate":"2025-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Antimicrobial Agents and Chemotherapy","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1128/aac.00968-25","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MICROBIOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Increases in macrolide resistance occurred recently among Streptococcus pyogenes (Group A Streptococcus, GAS) in some countries. While the importance of monitoring the clinical and molecular epidemiology of non-invasive GAS is increasingly recognized, most surveillance focuses on invasive infections, since culture is rarely performed in tonsillo-pharyngitis. We determined the antimicrobial susceptibility and characterized the macrolide-resistant lineages of 2,002 pharyngeal isolates recovered in a Portuguese hospital in 2014-2019. There were seasonal variations in the numbers of recovered isolates, with peaks shifting between March-July and October-December, but consistently low numbers in August and September. Macrolide-resistant and macrolide-susceptible GAS presented independent seasonal and clonal dynamics, with resistant isolates showing lower genetic diversity and minimal overlap with susceptible lineages. Overall, 84 (4%), 77 (4%), and 52 (3%) isolates were resistant to erythromycin, clindamycin, and tetracycline, respectively. Until 2018, macrolide resistance was mainly due to an internationally disseminated emm77-ST63 lineage carrying erm(A) and tet(O) in ICESp2905 and an emm75-ST49 lineage carrying mef(A)-msr(D) in a novel ɸ1207.3 variant. In 2019, resistance peaked at 9% due to the rapid expansion of mef(A)-msr(D)-positive emm2-ST55 isolates, replacing previous lineages. Other minor resistant lineages carried mostly erm(B) in a diversity of mobile genetic elements, including emm75-ST150, emm9-ST75, emm11-ST403, emm12-ST36, emm76-ST50, and emm77-ST399 [erm(T)]. Tetracycline resistance was associated with the genes tet(M) and tet(O), in most cases co-located in the same genetic elements as the erm genes. This study reveals clonal changes among macrolide-resistant GAS driving fluctuations in macrolide resistance and associated phenotypes.
期刊介绍:
Antimicrobial Agents and Chemotherapy (AAC) features interdisciplinary studies that build our understanding of the underlying mechanisms and therapeutic applications of antimicrobial and antiparasitic agents and chemotherapy.