Background: Two atypical serogroup 6 strains have been discovered. Results: They express capsular polysaccharide with two different repeating units and share A150T mutation in WciN. Conclusion: This mutation shifts WciN from a galactosyltransferase to a bi-specific glycosyltransferase, creating two new hybrid serotypes: 6F and 6G. Significance: Pneumococci can change capsule serotypes by point mutations and may alter their interactions with the immunity of the host. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.