Approximate numbers of cases per 100,000 individuals caused by penicillin resistance for each year (left). Approximate numbers of cases per 100,000 individuals caused by penicillin resistance for each year (left). These data encompass all clonal complexes and serotypes associated with penicillin resistance (MIC of ≥2 μg/ml) in cases of pediatric IPD during 1999, 2009, and 2013. The circle diameters reflect relative IPD incidences. Lindsay Kim et al. Clin. Microbiol. Rev. 2016; doi:10.1128/CMR.00058-15