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

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.

The Epidemiology of Invasive Group B Streptococcus in Denmark From 2005 to 2018

“…Moreover, there was a sharp increase in resistance rate of both antibiotics until 2009-2010, followed by a sharp decrease until 2012. These changes are very similar to changes in 2010 and 2011, respectively, reported by Martins et al (26) and Alhhazmi et al (19). We have not been able to identify any cause for these changes in Denmark, and the studies by Martins et al (26) and Alhhazmi et al (19) do not present an explanation to this observation either.…”

“…These changes are very similar to changes in 2010 and 2011, respectively, reported by Martins et al (26) and Alhhazmi et al (19). We have not been able to identify any cause for these changes in Denmark, and the studies by Martins et al (26) and Alhhazmi et al (19) do not present an explanation to this observation either. During the period 2014-2017, a decrease in the prevalence of erythromycin resistance was observed, and clindamycin resistance seems to have reached a steady level (Figure 3).…”

“…Serotype VIII seems to be more common in Denmark compared with many other Western countries, and the prevalence resembles more the findings in Taiwan (25). This serotype is very seldomly observed in other European countries and Canada (19,21,26). We have no explanation for the higher prevalence in Denmark.…”

“…Erythromycin and clindamycin are in general use in many countries, and resistance to these antibiotics is therefore monitored closely (19,26). For erythromycin resistance, we observed an overall significantly increasing trend during the period 2005-2018, although with large fluctuations, whereas clindamycin resistance showed a non-significantly increasing trend, also with large fluctuations (Table 2, Figure 3).…”

Incidence and serotype characterisation ofStreptococcus agalactiaein a Portuguese hospital

“…A laboratory-based surveillance programme that involved 22 Portuguese medical centres (from north to south)45 was also performed and has shown rates of 58.7% for serotype III, 22.0% for serotype Ia, 5.5% for serotype Ib and 4.1% for serotype V.…”