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. 2017 Mar 28:8:499.
doi: 10.3389/fmicb.2017.00499. eCollection 2017.

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

Elisabete R Martins  1 , Cristiano Pedroso-Roussado  1 , José Melo-Cristino  1 , Mário Ramirez  1 ; Portuguese Group for the Study of Streptococcal Infections
Collaborators, Affiliations

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

Elisabete R Martins et al. Front Microbiol. .

Abstract

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 >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/rib/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 (p < 0.001). Macrolide resistance was overrepresented among CC1 and CC19 isolates (p < 0.001 and p = 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.

Keywords: CC17; Streptococcus agalactiae; antimicrobial resistance; invasive disease; neonates.

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Figures

Figure 1
Figure 1
Invasive neonatal disease cases and live births in Portugal by year.
Figure 2
Figure 2
Erythromycin and clindamycin resistance in the study period.
See this image and copyright information in PMC

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