Increased Antimicrobial Resistance Among Nonvaccine Serotypes of Streptococcus pneumoniae in the Pediatric Population After the Introduction of 7-Valent Pneumococcal Vaccine in the United States

The proportion of S. pneumoniae isolates from U.S. pediatric patients covered by PCV7 decreased substantially in the 4 years after vaccine introduction. However, resistance to commonly used antimicrobials, including beta-lactams and macrolides, as well as multidrug-resistant strains increased significantly among respiratory tract isolates of NVS.