Characterization of 19A-like 19F pneumococcal isolates from Papua New Guinea and Fiji

Molecular identification of Streptococcus pneumoniae serotype 19F is routinely performed by PCR targeting the wzy gene of the capsular biosynthetic locus. However, 19F isolates with genetic similarity to 19A have been reported in the United States and Brazil. We screened 78 pneumococcal carriage isolates and found six 19F wzy variants that originated from children in Papua New Guinea and Fiji. Isolates were characterized using multilocus sequence typing and opsonophagocytic assays. The 19F wzy variants displayed similar susceptibility to anti-19F IgG antibodies compared to standard 19F isolates. Our findings indicate that these 19F variants may be more common than previously believed.