In general , new acquisition of pneumococci nonsusceptible to penicillin , erythromycin , clindamycin , penicillin plus erythromycin , and multiple drugs ( @ antibiotics ) was significantly lower in the PCV@ group compared with the PCV@ group ; the main serotypes contributing to this significant decrease were serotype @F , present in PCV@ and PCV@ , and serotypes @A and @A , present in PCV@ only .