Serotype-specific penicillin resistance of Streptococcus pneumoniae in Germany from 1992 to 2008

A total of 12,137 isolates from invasive pneumococcal disease was collected between January 1, 1992, and December 31, 2008, by the German National Reference Center for Streptococci (NRCS). Data on penicillin susceptibility were available for 11,814 isolates, whereat 8837 isolates (74.8%) were from adults, and 2977 isolates (25.2%) originated from children. Overall, the leading serotypes were serotypes 14 (16.5% of serotyped isolates), 3 (8.1%), 7F (7.7%), 1 (7.4%), and 23F (6.0%). The overall nonsusceptibility rate of all isolates adds up to 5.5% (intermediate, 4.3%; resistant, 1.2%) when the CLSI 2006 guidelines were applied, and to 1.4% (intermediate, 0.2%; resistant, 1.2%) when using the CLSI 2009 guidelines. Generally, slightly higher resistance rates were observed among children than among adults. Serotypes contributing considerably to pneumococcal penicillin nonsusceptibility by a combination of frequency among invasive isolates and relatively high penicillin nonsusceptibility are 19A, 9V, 6B, 19F, 23F, and 14. While the nonsusceptibility among serotype 19A isolates increased considerably over the years, the development of nonsusceptibility rates among the other serotypes is less and more ambiguous.