AUTHOR=Martins Elisabete R. , Pedroso-Roussado Cristiano , Melo-Cristino José , Ramirez Mário ,  The Portuguese Group for the Study of Streptococcal Infections , Oliveira Henrique , Vaz Teresa , Gião Marília , Ferreira Rui , Silva Ana Cristina , Costa Hermínia , Silva Maria Fátima , Afonso Maria Amélia , Domingos Ana , Marrão Gina , Grossinho José , Lopes Paulo , Felício Luísa , Lameirão Angelina , Vieira Ana Paula Mota , Tomaz Margarida , Ramos Maria Helena , Castro Ana Paula , Canhoto Nuno , Afonso Teresa , Pinto Margarida , Chantre Odete , Marques João , Peres Isabel , Daniel Isabel , Canas Ema , Ferreira Teresa , Marcelo Cristina , Monteiro Lurdes , Lito Luís Marques , Martins Filomena , Pessanha Maria Ana , Gonçalves Elsa , Morais Teresa , Marques Teresa , Toscano Cristina , Castro Ana Paula , Ribeiro Graça , Tomé Rui , Pontes Celeste , Boaventura Luísa , Chaves Catarina , Reis Teresa , Fonseca Ana Buschy , Ribeiro Manuela , Gonçalves Helena , Faustino Alberta , Alves Adelaide , Iglesias Maria Cármen , Cabral Luísa , Neto Olga , Sancho Luísa , Coutinho Adriana , Diogo José , Rodrigues Ana , Nascimento Isabel , Ramalheira Elmano , Bessa Fernanda , Diaz Raquel , Read Maria Antónia , Alves Valquíria , Monteiro Margarida , Rodrigues Vitória , Pereira Patrícia , Paixão Paulo 

TITLE=Streptococcus agalactiae Causing Neonatal Infections in Portugal (2005–2015): Diversification and Emergence of a CC17/PI-2b Multidrug Resistant Sublineage

JOURNAL=Frontiers in Microbiology

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2017.00499

DOI=10.3389/fmicb.2017.00499

ISSN=1664-302X

ABSTRACT=<p>The molecular characterization of 218 GBS isolates recovered from neonatal invasive infections in Portugal in 2005–2015 revealed the existence of a small number of genetically distinct lineages that were present over a significant time-span. Serotypes III and Ia were dominant in the population, together accounting for &gt;80% of the isolates. Clonal complex 17 included 50% of all isolates, highlighting the importance of the hypervirulent genetic lineage represented by serotype III ST17/<italic>rib</italic>/PI-1+PI-2b. Serotype Ia was represented mainly by ST23, previously reported as dominant among invasive disease in non-pregnant adults in Portugal, but also by ST24, showing an increased frequency among late-onset disease. Overall erythromycin resistance was 16%, increasing during the study period (<italic>p</italic> &lt; 0.001). Macrolide resistance was overrepresented among CC1 and CC19 isolates (<italic>p</italic> &lt; 0.001 and <italic>p</italic> = 0.008, respectively). While representatives of the hypervirulent CC17 lineage were mostly susceptible to macrolides, we identified for the first time in Europe a recently emerging sublineage characterized by the loss of PI-1 (CC17/PI-2b), simultaneously resistant to macrolides, lincosamides, and tetracycline, also exhibiting high-level resistance to streptomycin and kanamycin. The stability and dominance of CC17 among neonatal invasive infections in the past decades indicates that it is extremely well adapted to its niche; however emerging resistance in this genetic background may have significant implications for the prevention and management of GBS disease.</p>