Determination of Pneumococcal Serotypes by Sequetyping and Sequential Conventional Multiplex PCR in the Vaccine Era

Abstract

Pneumococcal serotyping is required for epidemiological surveillance to guide vaccination strategy. DNA-based approaches are more affordable, but the combination of sequetyping and sequential conventional multiplex polymerase chain reaction (cmPCR) may complement one another. A total of 101 isolates were subjected to sequetyping and sequential cmPCR following previously published protocols, and the outputs were compared. The sequetyping method determined up to the serotype level for 99 isolates (98%). On the other hand, the sequential cmPCR technique identified 91 isolates (90.1%), with 63 of them (62.4%) up to the serotype level. Sequetyping generated discrete serotypes for 6A/B, 11A/D, 15A/F, and 15B/C as 6A (n = 11), 6B (n = 10), 11A (n = 5), 15C (n = 1), and 15A (n = 1). In conclusion, the cpsB gene sequetyping method produced a comparable output with sequential cmPCR, further discriminating some sub-serogroups among the isolate collection.