Heterogeneity of rRNA gene restriction patterns of multiresistant serotype 6B Streptococcus pneumoniae strains.

Three multiresistant serotype 6B Streptococcus pneumoniae strains were isolated from the middle ear fluids of children undergoing tympanostomy in Atlanta. Because multiresistant 6B pneumococci have been reported to spread from a single clone, the three isolates were compared with 13 other multiresistant 6B pneumococci by hybridization of endonuclease-restricted DNA fragments with a digoxigenin-labeled cDNA probe complementary to 16 and 23S rRNAs (ribotyping). The ear isolates were heterogeneous, whereas six of the other pneumococcal isolates were alike, indicating a need for additional studies to determine the possibility of clonal spread.