Most of the isolates originated from adults ≥16 years (82.5%), while 17.5% were obtained from children <16 years. Penicillin resistance was observed in 7.2% of meningitis cases both among children and adults during the entire study period. In the post-PCV13 period, the resistance rate was 11.3% in children and 10.0% in adults, which is higher than in the pre-PCV7 and post-PCV7 periods. In the non-meningitis group, an overall penicillin nonsusceptibility rate (intermediate resistance and resistance) of 0.5% was detected both among children and adults. Nonsusceptibility rates among children were 6.3% (pre-PCV7), 7.6% (post-PCV7) and 9.0% (post-PCV13). The corresponding nonsusceptibility rates among adults were 4.4%, 6.0% and 7.9%, respectively. Concerning cefotaxime, in meningitis cases 0.8% of all isolates were intermediate and 0.5% resistant among children, while among adults, 0.9% were intermediate and 0.2% resistant. In non meningitis cases, cefotaxime nonsusceptibility rates were 0.5% in children and 0.3% in adults. Macrolide nonsusceptibility rates were lower in the post-PCV13 period (children 8.2%; adults 8.8%) than in the post-PCV7 period (children 17.3%; adults 13.0%) and the pre-PCV7 period (children 24.8%; adults 13.3%). In the pre-PCV7 period, macrolide resistance was mainly caused by M-phenotype clones carrying the mefA gene. In the post-PCV7/13 period, ermB (MLSb-phenotype) was the dominant resistance marker. Overall nonsusceptibility rates were 5.5% for clindamycin (intermediate 0.3%, resistant 5.2%), 0.7% for levofloxacin (intermediate 0.4%, resistant 0.3%), 8.5% for tetracycline (intermediate 0.6%, resistant 7.9%) and 11.0% for trimethoprim-sulfamethoxazole (SXT) (intermediate 5.7%, resistant 5.3%).
In summary, childhood pneumococcal conjugate vaccination has had a strong effect on the pneumococcal population in Germany, both among vaccinated children as well as among non-vaccinated children and adults. Serotypes included in the pneumococcal conjugate vaccines have strongly diminished, while some non-vaccine serotypes have gained importance, particularly with respect to antibiotic resistance. However, concerning antibiotic non-susceptibility the most outstanding change over the years is the decline in macrolide resistance, especially among children.