Invasive pneumococcal infections in France: Changes from 2009 to 2021 in antibiotic resistance and serotype distribution of Streptococcus pneumoniae based on data from the French Regional Pneumococcal Observatories network

Objective: The 23 French Regional Pneumococcal Observatories (ORPs) analyzed antibiotic resistance and serotypes of Streptococcus pneumoniae strains isolated from invasive infections in France over a 12-year period. Methods: Between 2009 and 2021, the ORPs analyzed 19,319 strains, including 1,965 in children and 17,354 in adults. Strains were assessed for their resistance to penicillin G, amoxicillin and cefotaxime. Serotypes were identified in collaboration with the National Reference Centre. Results: During this period, the number of strains collected yearly decreased significantly. The decrease was particularly pronounced up until 2013, especially in children (-61.0%). However, penicillin non -susceptible strains (PNSPs) increased in children (24.7% in 2009 vs 45.0% in 2021, p < 0.0001) and in adults (27.1% in 2009 vs 31.3% in 2021, p < 0.05), as well as resistance (I + R) to amoxicillin (children: 12.5% in 2009 vs 19.4% in 2021, p < 0.05; adults: 13.4% in 2009 vs 14.5% in 2021, NS) and resistance (I + R) to cefotaxime (children: 8.0% in 2009 vs 13.1% in 2021, p < 0.05; adults: 7.1% in 2009 vs 11.9% in 2021, p < 0.0001). All in all, the proportion of strains belonging to serotypes present in the PCV13 vac-cine has fallen sharply, from 64.8% in 2009 to 23.6 % in 2021. At the same time, serotypes such as 8, 10A, 11A, 15B/C and 9N, not included in PCV13, were increasing. Conclusion: During the study period, data collected by the network highlighted an increase of invasive PNSPs in children and non-vaccine serotypes. Surveillance of resistance and serotypes remains instru-mental, particularly to monitor the evolution of vaccine efficacy.